Acknowledgments

The widespread interest in the first edition of this book and in other booksexploringthedeepseahasmadeiteasytogenerateenthusiasmtoproducethisrevised editionwith updated and greatly expanded text, the latest photographsandanewdesign.First, I must thank the scientists who are slowly uncovering the secrets of

thesedeep-seacreatures.Forwithoutthesteadyprocessionofnewdiscoveries,there would be no need for another journalistic expedition across the oceanexpansesandtothedeepestwatersofourplanet.Inessence,weallneedtothankthe creatures themselves for inspiring such wonder and for turning up at asurprisinglysteadyrateyearafteryear—2,000newspeciesperyearsince2000.Inaddition,Iwouldespeciallyliketothanktwoofmyfavoriteeditors,Tracy

C. Read and copy editor Susan Dickinson, along with Lionel Koffler andMichaelWorekatFirefly, formaking thisbookpossible.Allwere involved inthefirsteditionofCreaturesoftheDeep,sothereisastrongcontinuity.Iwouldalso like to thankFirefly’sPippaKennard for coordinating the photos and forfacilitating every aspect of the book’s production, designer Hartley Millson,illustratorGeorgeA.Walker, indexerGillianWatts and all the photographers,especially David Shale, for his unfailing help with background details on hisdeep-sea images, andSandra Storch,who provided the background for SolvinZankl’sphotos.ErikaFitzpatrickprovidedenormoushelpwiththeWoodsHoleOceanographic Institution images. Iowemypassionandsomeofmy thinkingon biodiversity, protected areas and whale conservation in the book’s finalsection to a number of friends and colleagues, including Tundi Agardy, JeffArdron, Regina Asmutis-Silvia, Brad Barr, Mike Bossley, Alexander Burdin,ChrisButler-Stroud,SarahDolman,NicolasEntrup,IvanFedutin,OlgaFilatova,Naoko Funahashi, Kristina Gjerde, Nicola Hodgins, Miguel Iñíguez, TanyaIvkovich, Kristin Kaschner, David Mattila, Naomi McIntosh, Cara Miller,Mikhail Nagaylik, Peter Poole, Margi Prideaux, Patrick Ramage, RandallReeves, Lorenzo Rojas Bracho, Mark Simmonds, Liz Slooten, Brian Smith,Michael Tetley, Vanesa Tossenberger, José Truda Palazzo Jr., RobWilliams,VanessaWilliams-Grey, Edward O.Wilson, AlisonWood and especially myfellow chair of the IUCN Marine Mammal Protected Areas Task Force,GiuseppeNotarbartolodiSciara.Iwouldliketoexpressmydeepestappreciation

to biological oceanographer Paul Snelgrove at Memorial University ofNewfoundland and Labrador, Canada, who read the entire text and providedexcellent suggestions andcorrections. In addition,CharlieHuveneersprovidedvaluable comments on the sections about sharks. Of course, any errors thatremainaremyown.Ourpassionandbeliefinthiseditioncomesfromtheoceanitselfandthedesiretosharenewinsightsintothisstrange,deepworld.

—ErichHoytBridport,Dorset,EnglandMay2014

CONTENTS

Author’sNotePrologue

PartOneDownThroughtheLayersTheLayersoftheSeaSurfaceWaters:TheEpipelagic(Euphotic)ZoneMiddleWaters:TheMesopelagic(Disphotic)ZoneDeepWaters:TheBathypelagic(Aphotic)ZoneDeeperWaters:TheAbyssopelagicZoneDeepestWaters:TheHadalZone

PartTwoAFish-Eat-FishWorldPlanktonicDramasTheCosmopolitanCopepodJellyfish:BidingTimeBigSharks1:ThePlankton-StrainersDancingwithSquidBigSharks2:TheFlesh-EatersKillerWhalevs.SharkDownDeepwithDragonfishTheWeb

PartThreeTrekkingDowntheRidgeTheLongestMountainChainintheWorldTheWorldOceanFloorCreaturesintheSulfurGardenFartherAlongtheRidgeandBackinTimeBlackSmokersandNewLife-FormsLifeAmongtheArchaeans

PartFourCountingtheCitizensoftheSeaTheCensusofMarineLifeFindingaPlaceforOceanCitizenstoLiveDecidingontheKindofOceanWeWantorLifeAmongtheJellyfishEpilogueSourcesandResources

AuthorBiography

PhotoCredits

Theacornworm,orenteropneust(Yodapurpurata),whichfeedsonseafloorsediment,wasdiscoveredin2010abovetheMid-AtlanticRidgeandnamedin2012.Theenteropneustsharesanatomicalfeaturesofbothinvertebratesandvertebrates.Someevolutionarybiologiststhinkitmayhavegivenrisetothe

vertebrates.

I

Author'sNote

“YouthoughtIshouldfindnothingbutooze…andI’vediscoveredanewworld!”

H.G.Wells,IntotheAbyss

N2001,when the firsteditionofCreaturesof theDeepwaspublished, Iwrotethatwewereembarkingonagreatcenturyofdiscoveryinthedeepocean.Thatprediction isoncourse. In2007, fishermenoffNewZealand

hauledtothesurfacethelargestcolossalsquideverseenbyhumans(thoughstillneverobservedaliveinitsnaturalhabitat).In2010,researchersreportedontheCensusofMarineLife, adecade-long investigation into life in theoceans thatdescribedsome6,000potentialnewspecies,mainlyinthedeepsea.Soonafterthat announcement, scientists raised the estimated number of oceanic speciesnamed and known to science from 220,000 to 240,000, an increase of 20,000new species that make their homes in the sea. Thanks to an expedition thatlaunched fromJapan in June2012,wewere able towatch the first videoof alivinggiantsquidinthewild.Alsoin2012,afteragapof50years,wesharedthe excitement of the secondmanned visit to the deepest spot in the ocean—Challenger Deep, at the southern end of theMariana Trench—undertaken byfilmmakerJamesCameron.There’smuch,muchmore.Forexample,in2006,ontheNorthIcelandicShelf

nearGrímseyIslandontheArcticCircle,researchersfromBangorUniversityinWales dredged up what they took to be 400-year-old specimens of the clamArcticaislandica.Theageofoneof theclamswassubsequentlydeterminedtobe 507 years, which was confirmed by carbon dating. The longest-livednoncolonial animal with an accurately determined life span, this clam wasnamedMing,atributetothefactthatithadstartedlifeduringtheChineseMingDynasty.WhilethereisnowayofknowingjusthowmuchlongerMingmighthavelivedhadtheclambeenleftontheoceanfloor,itsdiscoverydoesleadustowonderwhatsecretstoalongandhappylifearetobefoundinthecoldwatersnorthofIceland.

Aroundthedeep-seahydrothermalvents,researchershavediscoveredthescaly-foot snail—a gastropod with a hard-shell foot adapted to withstand hotconditions—andthefurryabominablecrab,alsoknownastheYeticrab.Foundin the South Pacific Ocean in 2005, this crab has a fur coat, which seemsstrangelyoutofplaceforacreaturelivingnearasitewheresupercriticalwater(whose physical properties lie between those of a gas and a liquid) pours outfromthehottestpartsoftheventsattemperaturesupto867degreesF(464°C).And there is not just one Yeti crab but several and perhaps many; differentspeciesappeartoliveatdifferenthydrothermalvents.Yeticrabshavealsobeendiscoveredatso-calledcoldvents,orcoldmethane

seeps,wherewatertransportsdissolvedelementsfromtheseabed.OregonStateUniversity’sAndrewThurberandhiscolleaguesuncoveredanotablenewYetispecies, Kiwa puravida, during an Alvin submarine cruise off Costa Rica in2006. A microbe specialist, Thurber studied how the new Yeti rhythmicallyswings its chelipeds, or claws (which are covered indense setae and epibioticbacteria), above themethane seep inwhat appears to be a form of symbiosiswith thebacteria.TheseYetiare thought tofarmthebacteria,caringfor them,nurturingthemandperhapsconsumingthem,muchliketheantsthatstandguardoversubduedaphids,feedingfromtheirsugarysecretionsand,asneeded,eatingtheaphids.Many such “tiny fauna” stories reveal the lives of microbes—the bacteria,

archaeans and other mostly single-cell organisms called protists—that live insymbioseswithsquid, jellyfishandzooplankton,providingasourceoffoodaswellaslightforcommunicationandmore.Microbesaresohardythattheycanliveinsiderocksthatlie1,900feet(580m)belowthedeepseafloor.Most estimates of biological diversity in the sea hover around one million

species, but according to some biologists, 10million species is not out of thequestion.Clearly,wearestillatthebeginningofthegrandadventurethatisthehuman effort to understand these species and their relationships with oneanother.Butifeveryspecieshasastory,thenanecosystemislikeamultilayeredepicnovel,onethatdetailstherelationshipsbetweenthenovel’scharacters.Asasetting,theoceanhasthemostextensive—andsomeoftherichest—ecosystemsonourplanet.Ecosystemisoneofthosefuzzywords,overusedanddimlyunderstood.The

OxfordDictionary defines it simply as “a biological community of interactingorganismsandtheirphysicalenvironment.”Forourpurposes,thismeansalllifein the sea, aswell as the sea itself, including the seamounts and trenches, themidoceanridgeandthenutrientmatterfloatingthroughthedeep.Theecosystemis the network of all the above and their interactions. The question is:Where

doesanecosystembeginandend?Someconversationsconfineanecosystemtoa small space about the size of a room, a house or a neighborhood; otherdiscussions consider the ocean ecosystem as one system; some, like scientistJamesLovelock,regardEarthanditsatmosphereasoneecosystem.What we’re talking about here resides somewhere between these extremes.

Wemightusefullyconsideranecosystemfromthepointofviewofananimal,itscommunityofinteractingorganismsanditsphysicalenvironment.Inthecaseofaseacucumberfilteringmatterfromtheoceanfloor,thisenvironmentmayberelatively small. But for a barnacle on a humpbackwhale thatmigrates about5,000miles (8,000 km) twice a year, it’s clearly extensive. Yet even the seacucumber inching along the seafloor depends onmatter drifting down from asurfacethatmaybesevenmiles(11km)away.Akillerwhale’secosystemmayextendtopreythatswimsthousandsofmilesupriver,suchassalmon.Of course, it’s not just amatter of our being intrigued and delighted at the

richnessofthisplanet’secosystems,althoughthatwouldbeenough.WhenIsetouttowritethefirsteditionofthisbook,Iwasdeterminedtounravelthestoriesabouttrueandimaginedmonstersofthedeepsea,eventorehabilitatetheimageof thosemonsters, ifpossible.Over time, thepublic’sperceptionof somehas,indeed,beentransformedforthegood,whileothersareperenniallyregardedasmonsters,withorwithout justification.Thesecreatures range insize from tinymicrobestogiantsquid.Someareconventionallyuglybutharmless.Othersarebeautiful but dangerous. Yet without question, among these “monsters” arepotentialsourcesofmedicineandexamplesoflifestrategiesandgeneticdesignsthatmayinspirefutureinventions,innovationsandartisticcreations. At the same time, humans continue to place incredible life-threatening

challenges in the path of many ocean species, reducing and even eliminatingpopulations through pollution, hunting, collisions at sea, fishing-gearentanglements, noise, indiscriminate overfishing and,more than anything else,injuryanddeaththroughunintendedcatchesbycommercialfishermen.Thisso-called bycatch includes an annual tally of an estimated 300,000 whales anddolphins,millionsofsharksanduntoldnumbersofturtles,sealsandfish.Thuswe are in a race both to identify the problems and to solve them, even aswestruggle toget abetter ideaofwhich specieswemaybe threateningandevenlosing.

ArcticaislandicaclamslivingnorthofIceland,neartheArcticCircle,areatleast400yearsoldandmay,insomecases,livemorethan500years,accordingto

researchersatBangorUniversity,inWales.

TheYeticrab(Kiwasp.)livesaroundhydrothermalvents,suchastheDragonVentFieldintheSouthwestIndianOcean,andappearstoharvestthe

chemosyntheticbacteriaitcollectsonitshairyundersideasafoodsource.

Thehumpbackwhale(Megapteranovaeangliae)feedsandbreedsininshorewatersandsometimesbecomesentangledinfishinggear—inthiscase,crabpotlinessetoffthecoastofHawaii.Despiteanumberofsuccessfuldisentanglementprograms,anestimated300,000whalesanddolphinsdieaccidentallyeveryyear

innets,linesandotherfishinggearthroughouttheworldocean.

Thesmoothtailmobula(Mobulamunkiana),orpygmydevilray,takesflightinCaboPulmoNationalMarineParkinBajaCaliforniaSur,Mexico.IdentifiedbyItalian scientist Giuseppe Notarbartolo di Sciara in 1987, smoothtail mobulasoftencongregateclosetoshoreinthetensofthousands.

“M

Prologue

ONSTERS:AliveandWellandLivingintheDeep.”Thatnewspaper headline says it all. It could be 2014, 1914,1814or,ifdailynewspapershadbeeninvented,314BCin

Greece.Countlesssuchheadlinesreachbackhundredsofyears,andthestoryisessentiallythesame.Few human beliefs are more basic and time-honored than the idea that

monsterslurkinthedeep.Astheextentofourknowledgeoftheknownlimitofthe deep sea has grown over the centuries, the supposed sea monsters havechanged,buttheoveralllengthofthelisthasnotdiminished.Whaleswereonceconsideredseamonsters.Onetranslationofkētos,theGreekoriginofthewordcetacean—the name for allwhales, dolphins and porpoises—is “seamonster.”Forthewhale,thechangefromseamonstertofriendlyseamammaloccurredinthelate20thcentury,aspeoplebegantolearnmoreaboutwhalesandembracethem.Asimilartransitionishappeningformanyofthesharksandrays.Atonetime,

sailors were terrified of the basking and whale sharks’ open-mouth feedingstrategy,whichlookslikeanattackposture,butnowsuchplankton-eatingsharkshavebecomeobjectsofcuriosityratherthanhatedandmisunderstoodcreatures.Theelegantmantaray,onceknownasthedevilfish,wasreputedtograbshipsbytheir anchors and drag them into the deep. Swimmerswere terrified that theywouldbesurroundedbythemantaray’slargefinsandswallowedwhole.Today,however,diversplaywithmantasandotherraysandmarvelwhentheyburstoutofthewaterandperformasaerialartists.Certain sharks, suchas thewhite, tigerandhammerhead, remain in the sea-

monstercategoryformostpeople,althougheventheseanimalsareincreasinglyevoking sympathy. The 1975 movie Jaws, based on the best-sellingPeter Benchley novel, may have been good entertainment, but it instilled awidespreadfearandhatredofsharksandencouraged theirslaughter—hardlyasympathetic portrait. Still, the book and the film sparked a curiosity about

sharks,andsomeofthisattentionproducedabacklashofsympathy.Inanycase,theconservationofsharkshasbecomecrucialinthepost-Jawsera.Asmoreandmore people learn about sharks—as they did about whales a decade or twoearlier—they come to realize that only a few individual animals attack peopleand that evenwith thewhite shark, such attacks are rare.Once known as the“greatwhiteshark,”thisspeciesisincreasinglyreferredtosimplyasthe“whiteshark,” partly in an effort to defuse the negative connotations that have longbeenattachedtoitsoriginalcommonname.Eachyearoverthepastfewdecades,despite the presence ofmillions of sea swimmers, divers, surfers and boaters,therehavebeenroughly75recordedsharkattacksonhumansworldwideandanaverageoffewerthanfivefatalities.In the late 1970s, unbeknownst to most of the public, a new bestiary of

monsters began to appear in the form of giant tubeworms and strange crabs,snailsandothercreaturesthatflourishdeepinthesea,intheabsenceofsunlight,athydrothermalventsspewingsulfur-richwater.The tubewormsactuallydrawtheirenergyfromsulfur-eatingbacteriathatliveintheirstalks.Asthediscoveryof life at these hydrothermal vents made scientific headlines, new monsterstoriesbegancirculating,thistimetoldbythescientiststhemselves.Sincethen,scientistshavesearchedforandbeguntostudymanyotherdeep-

seacreatures.In1995,Timemagazineproclaimedthenewfrontierofdeep-searesearchwithacoverphotoofavicious-lookingdeep-seaanglerfishsportingamouthfulofneedleteeth,bioluminescentluresandsaucereyes.Everyfewyearssince then, popular magazines and aquarium exhibits have tried to raise theprofile of the deep sea with mixed success—the public’s intense curiosity isstimulated,butisthatenoughtoproduceatrueunderstandingoftheocean?TheCensus of Marine Life’s ambitious 10-year project (2000–2010) to find andidentifynewspeciesinthedeep,forexample,broughtmanythousandsofdeep-seaspecies to thepublic’sattention. It’sastart.But therearestillhundredsofthousands,perhapsmillions,ofspeciesyettobediscovered,namedandstudied.Some “seamonsters” are both age-old and current, yet we still know little

aboutthem.Thegiantsquidtopsthelist.FirstphotographedaliveinSeptember2004 off Ogasawara, Japan, the giant squid continues to be the subject ofscientificexpeditionsattemptingtostudyitinitsnaturalhabitatandunlockthesecretsofhow itmakes its living,despite thehundredsof thousandsof spermwhalesthatareeverinhungrypursuit.Aspermwhaleeatsanestimatedoneortwo giant squid a week, but no one has yet documented the ultimate giantsquid/sperm whale contest. In addition to giant squid, there are supposedmonsters of every size, description, demeanor and depth: oarfish, sea snakes,gulperandsnipeeelsandcolossalsquidamongthem.

Humanstraditionallyreservethegreatestawe,fear,hatredandevencontemptforseamonstersthatarebigpredators.Whilemanybig-toothedorpoisonousseacreatures deserve arm’s-length respect, that hardly renders them monsters orodious.The idea of what makes a “monster” changes over time. Perhaps that

perception reflects a fear of the unknown or the poorly known.Misunderstanding or a certain lack of knowledge leaves room for the humanimagination to fill in the blanks, less encumbered by science and real naturalhistory,thuselevatingsomecreaturestosea-monsterstatus.The word monster comes from the Old French/Middle English monstre,

which,inturn,isderivedfromtheLatinmonstrum(“portent”),frommonēre(“towarn”).Thekeydictionarydefinitionofmonsteris:acreaturewithastrangeorfrightening appearance. But strange is relative, and therefore, amonster takesform,atleastpartly,intheeyeofthebeholder.Secondarydefinitionsare:averylarge animal, plant or object [note: size, too, is relative]; an animal, a fetus, aplant or other organism having structural defects, deformities or grotesqueabnormalities [note: normality is also relative]; one that inspires horror ordisgust, a monster of selfishness [note: horror and disgust are even morerelative]; and an imaginary or legendary creature, such as a centaur, thatcombinespartsfromvariousanimalorhumanforms.Partofthefascinationwithseamonstersistheenduringmysteryofthedeep

andmurkyplacestheyinhabit.Thesurfacewatersaccessibletoboats,diversandswimmersrepresentjustathintoplayer,theskinoftheworldocean,lessthan1percentof its336-million-cubic-mile (1.4billionkm3)habitat,whichaverages2.3miles(3.7km)deep.Inearliertimes,peoplehadasmanymisconceptionsabouttheseaastheydid

aboutseamonsters.Somethought that thewateron thebottomwassocold, itmust be frozen or that the water there was eternally, fatally stagnant. Othersimaginedthatthepressurewassogreat,deadanimalsorevenshipswhichsankintothedepthswouldbeunabletofalltothebottomandwouldremain,foreverconstrained,inasuspendedstateinthegreatabyss.In themid-19th century, as expeditionswere launched to explore life in the

depths, one of themore popular theories suggested the absence of life below1,800feet(550m),or300fathoms.Withagrowingscientificunderstandingofthe conditions needed to sustain life, themid-to deepwaters were consideredsunlessandtoocoldtosupportlivingorganisms.Thatideawasbasedonlimitedresearch in unproductive regions of theMediterranean and ran counter to theprevailing idea of deep-sea monsters. If no life existed below 300 fathoms,wherewouldtheputativeseamonstersliveandwhatwouldtheyeat?Thelate-

19th-century Challenger Expedition demonstrated widespread life in the deepsea,andinthemid-20thcentury,lifewaseventuallyshowntoextendfromthesurface to theverybottomof thesea, in trenchessevenmiles(11km)deep. Itwascoldanddarkonthebottom,andthingsmovedslowly.Butevenhere,therewere monsters of a kind, yet those who discovered them were not so muchfrightenedasheartenedtofindanythingatsuchdepth.The deep sea refers to the layers of water nearest the bottom of an ocean

basin,althoughitissometimesusedcasuallytorefertothevastopen,orpelagic,ocean—the offshore waters lying off the continental slope, where the deepestseasarefound.Inthisguidedtourofthedeepandpelagicocean,wewilljourneythroughthe

various layers, everdeeperand tomore remotecorners, andmeet someof thefascinatingcreaturesof thedeepthat looselymakeupthegroupofformerandcurrent“seamonsters.”Thisbooknotonlypresentsa rogues’galleryofdeep-seamonstersbutalsoexploresthekindofworldthatgivesrisetosuchcreatures.Itismyferventhopethatthisintroductiontothedeepwillturnafewmoreseamonsters into sea friends, animals worthy of our respect, curiosity andadmiration,aswellasourcareandconcern.It’stimetomakefastfriendswithseamonsters. The ocean that gave them and us the gift of life is changing inways that humans are trying to understand.Will that understanding come toolate?

ThemarinelarvalformofadecapodcrustaceanofthegenusSergesteslivesintheAtlanticOceanatadepthofsome10,000feet(3,000m).This10-footed

crustaceanhasdelicatehighlybranchedantennaethatallowittofloatinthedeepwatercolumn.

With a maximum length of six inches (15 cm), the common fangtooth(Anoplogaster cornuta) has someof the largest teeth (relative tobody size)ofanymarinespecies.Thefangsinthelowerjawarematchedbysocketsoneithersideofitsbraintopreventtheteethfrompiercingthebrainwhenthefangtoothclosesitsmouth.Itlivesintheworldoceanatdepthsof600to6,500feet(180–2,000m)buthasbeenfoundasdeepas16,000feet(4,900m).

PARTONE

Previouspage:Describedbyscience in1997, theblackseanettle (Chrysaoraachlyos)isalarge,rarejellyfishthatlivesinthedeepseaaroundtheCoronadoIslands,offBajaCalifornia,Mexico.

Themauvestinger(Pelagianoctiluca)sparkleswithbioluminescentlighttoattractzooplanktonpreytoitstentacles.Foundineveryocean,thisjellyfishhasinvadedfishfarms,stingingandkillingmassesoffarmedsalmon,andinundated

Mediterraneanbeaches,forcingswimmerstofleefromthewater.

T

DownThroughtheLayers

JourneytotheBottomoftheSea

HEPOWERFUL,almostirresistibleurgetoglimpsewhatisgoingonbelowthesurfaceof thesea isan immediate,persistent,everpresentdesire of humankind—and is something I have felt keenly onmany

occasions.Rockingtoandfroonashipabovethemile-deep(1.6km)KaikouraCanyon,

east of New Zealand’s South Island, I listen to the laconic clicks of spermwhales pickeduponhydrophones, underwatermicrophones connected to twinloudspeakers on the ship, and long to see the fabled battles between spermwhalesandthegiantsquid.Itisnotable—butnotenough—toknowthatspermwhales carry scars from giant squid tentacles and that squid beaks have beenfound in the stomachs of stranded sperm whales.We want to see the battlesroyal, the battles that no one has yet seen, not even Clyde Roper, the U.S.NationalMuseumofNaturalHistory’s quintessential squidman, despitewell-funded Discovery Channel, NHK (Japan Broadcasting Corporation) andNationalGeographicSocietyexpeditions.On another occasion, sitting in an underwater viewing chamber in the

pontoonsofacatamarancruisingnearthevolcanicCanaryIslands,offnorthwestAfrica,Istraintoseeintothedepths.Dolphinsandpilotwhales, thenaflying,swoopingmantarayedgeintoviewbeneaththeboatandshadowsof—coulditbe?—amassivewhaleshark.Ormaybenot—butsomethingbig.Evenwithoutknowingwhatitis,Iyearntofollowitasitdisappearsintothedepths.But the deepest ambition comes high above the sea on a clear-day flight

between Tokyo and Brisbane, Australia. Approaching the Mariana Trench, Igaze out the plane’s window at what I imaginemust be the darkest patch ofocean on Earth. After many miles of speckled coral reef atolls, with theirbright ringsofcolorand thesea reflecting that robin’seggblueofclearwaterand sandybottom,milesofblack sea seemsomething tobe reckonedwith. In

truth, Iwaswaiting tocross this spot,plotting theposition from islandsasweflewover—somethingIdotopassthetimeonlong-haulplanejourneys.Itmaybepartlymyimaginationthatitseemssoblackdownthere.However,thereisnodoubtaboutthelocationandthefactthatthedeepestsealiesbelow:Atjustover35,800feet(10,900m),ChallengerDeep,intheMarianaTrench,isthegreatestdepth on Earth. No champion Pacific Islands’ pearl diver could ever havecontemplatedsuchadepth.Indeed,onlyfourdeep-seavehicleshaveevermadethe full dive to the bottom of the world: the bathyscaphe Trieste,manned byJacques Piccard andDonWalsh in 1960;Kaikō, a JapanAgency forMarine-Earth Science and Technology unmanned tethered craft, in 1995; Nereus, aWoodsHoleOceanographicInstitutionremotelyoperatedvehicle,in2009;andtheDeepseaChallengersubmarine,whichcarriedfilmmakerJamesCamerononasolodivein2012.Allmadebrieftrips,duetotheintensepressure,butatleastCameron, as might have been expected, remembered to take along a fewcameras.Flyingat37,000feet(11,300m),weareaboutasfarfromtheoceansurface

asthatsurfaceisfromthebottomofthetrench.Itisawonderfullysymmetricalimage.Butthetwoplacescouldnotbemoredifferent.Uphere,thelowpressureoutside the plane—the thin air—is about three pounds per square inch (psi),comparedwith 14.7 psi at sea level.At the bottomof the sea, the pressure is“thick,” extremely heavy—more than 16,000 psi, or 1,100 times our ownatmosphere on land. The pressure of water at depth is so much moreuncompromising than are the conditions of thin air. Long before reaching thebottom,allexceptthosespeciallybuiltsubmersibleswouldcollapselikeasodacan. In truth, it ismore routine and less technicallydifficult to travel in spacethan it is toventure to thebottomof thesea—thedeepest,densestanddarkestplaceonEarth.

Curiosityabouttheseaprobablybeganwiththefirstcoastal-livinghumans,nodoubtsurprisedbywhatevernewmonstertheseamightpresentattheirdoor,usually

heavedonshorefollowingastorm.

ItisoftennotedthattheMarianaTrenchatChallengerDeepisdeeperthanthehighestpointonEarth,MountEverest.IfEverestwereplacedat thebottomof

thetrench,itspeakwouldstillbe7,000feet(2,130m)belowthesurface.Yetthemassivesizeofthisdeeptrench—morethan100timesthatoftheGrandCanyon—israrelyreported.Curiosity about the seaprobablybeganwith the first coastal-livinghumans,

whowerenodoubtsurprisedbywhatevernewmonstertheseamightpresentattheirdoor,usuallyheavedonshorefollowingastorm—oftenedible,at timestobefeared,alwaysimpressive.Sometimes,itwasagiantbluewhaleoranarwhalwitha10-foot(3m)tuskthatfueledstoriesoftheunicorn.Itcouldbeasquidwith impossibly long tentacles or a fish with a mouth full of sharp, graspingteeth,fearsomeandthestuffofbaddreams,evenifitwaslyinghalfdeadonthebeach.Mythsarose.TheancientGreeksbelievedthatKingPoseidon,thebrotherof Zeus, ruled the waters, while in Romanmythology, it was Neptune. Longbeforeitbecameconnectedwiththatdistantplanetinoursolarsystem,Neptunewasanothernamefortheseaandevokedthegreatdepthssolittleknown.Some of the earliest deep-sea stories date toAlexander theGreat (356–323

BC), though thedetailsareoftensketchy,contradictoryandshrouded inmyth.When he wasn’t battling his enemies, as well as his colleagues, AlexanderexploredthewateryrealmsoftheeasternMediterranean.Hedescendedandtriedto stay underwater in an early prototype of a bathysphere—a diving bell thattrapped air underwater—to watch the fish. He saw sea monsters too; onecreature was purportedly so big, it “took three days” to swim past hisunderwaterglasscage.Asanyfishermanknows,thestoriesoffishthatgotawaygrowmore fantastic as they are retold over time, and the tales of Alexander,whichhavebeenpasseddown tous invarious languages,havehadmore than2,000yearsofretelling.ButitdoesseemthatAlexanderhadagenuinecuriosityaboutthesea.Perhapspartofthisdeep-seapassioncameviaAristotle(384–322BC),whotutoredhimfromage13to16.

Twoyoungspermwhales(Physetermacrocephalus)offtheAzores,preparetomakeadeepdiveinsearchofsquid.

Aristotle was, among many other things, the first marine biologist, and hiscareful biological work is documented in his Historia Animalium. He spentseveral years observing marine life and talking to fishermen on the island ofLésvos,andintheprocess,heidentified180marinespeciesintheAegeanSea.Themostmonstrousfindingsonhislistwerevarioussharksandtheelectricray,butAristotle,everthematter-of-factbiologist,didnothypethedangeraswouldsomanylaterwriters.PlinytheElder(23–79AD),bycontrast,described“seamonsters”inalmost

lurid detail. Specializingmore in library research and less in fieldwork, PlinydownsizedAristotle’s totalmarine creature count to 176 species and declaredthat this was the grand total for all the world ocean, chronicling his ownignorance for future generations. He added to his blunder by stating that theanimals of the deep had all been found andwere better known than those onland.Even today,althoughwehave learnedmuchabout theocean,ouroverallknowledgeofthedeepsearemainspoor.After Aristotle, scientific interest in the deep sea receded until the Age of

Discovery.AlongwiththeEuropeanquesttoconquerunchartedlandsandfindtraderoutes,goldandthefountainofyouth,therecameanewcuriosityaboutthesea. According to Ferdinand Magellan’s log of the first round-the-worldexpedition (1519–22), his men had made “soundings” using a length of ropelowered over the side to measure the depth of the water when searching foranchoragenearthewesternPacifictrenches.Whentheropefailedtohitbottomat2,400feet(730m),theydeterminedthattheywereoversomeofthedeepestspots inthesea.Laterexpeditionsusedwiresoundings,oftenemployingpianowire,sometimeswithacannonballattached,butitwaslikewisedifficult totellwhenthesehitbottom.Therewereevenreportsofsoundingsreaching10miles(16km)ormore—deeperthanthedeepesttrench.Theneedforaccuratesoundingsincreasedasshipsenteredunfamiliarcoastal

waters and wanted to avoid running aground. Even before the great ocean-mappingvoyagesofthe19thcentury,inquisitiveness,ifnothingelse,promptedcaptains to drop the lines ever deeper. Sometimes, brittle stars or othercreaturesgrabbedholdof these lines, and the ship’snaturalistordoctor (oftenthesameperson)wouldthengetaglimpseoflifebelow.But,forthemostpart,theseexplorerswereintriguedbynewlands,notunderwaterworlds.Theseawasjust a passageway, and the goalwas to traverse theworld of seamonsters asquicklyaspossible.Later,ofcourse,thesearchforwhaling,fishingandsealinggrounds led to amore direct interest in the sea, but one thatwas stillmainlyfocused on surface coastal waters. Not until the development of a method ofsendingandmeasuringsoundpulses throughthesea in the1920sdidmariners

obtain the first accurate measurements of the deep sea. Hundreds of echosoundingscouldbemadeinthetimeittooktopayoutonelineandpullitin.Yetitwaspossibletocollectsamplesonlybydredges.Adaptedfromfishing

implements,dredgesforcollectingsealifewerecrudetriangular-shapedframespartly covered with fine net or wire mesh attached to lines. They could beloweredandsetdownonordraggedalongthebottom,thenhauledtothesurfacewiththe“catch.”Asdredgesforcollectingsamplesbecameavailableinthe19thcentury, scientists began to gain a better idea of what lived in ever deeperwaters.AnearlychampionofthedredgewasBritishnaturalistEdwardForbes(1815–

54),who,asayoungmanin1839,receivedagrantfromtheBritishAssociationfor the Advancement of Science to set up a “dredging committee.” His firstdredgingjobcameshortlythereafter,asnaturalistonboardtheHMSBeacononan 18-month naval expedition to survey Aegean waters—the same watersAristotle had studied some 2,000 years earlier. Forbes eagerly pulled uphundreds of species, some of which had been noted by Aristotle. AlthoughForbessampledonlytherelativelyshallowbottom,downto1,380feet(420m),hefoundthatthenumberofspeciesdeclinedrapidlythedeeperhewent.Writingin1840,hepostulatedthateachofeightdifferentdepthzonescontainedseparatefaunasandthataninthzone,whichencompassedthebottomwatersandoceanfloor below 1,800 feet (550 m) could support no life. He called this lifelessregionthe“azoiczone.”Matthew Fontaine Maury (1806–73), regarded as the father of American

oceanography, agreed with Forbes, remarking that the azoic-zone idea“conformsbetterwiththeMosaicaccount”—thebiblicalLawofMosesandthestory of the origin of theworld according toGenesis,which reveals preciselynothingabout thedeepsea. InForbes’andMaury’sday, theneed to reconcilesciencewithreligionwaspartofacademiclife.Evenwhendredgesdid reachwell into theazoiczone, therewereproblems

drawingconclusionsabouttheseafromthedredgesamples.Dredgesmissedallthefree-swimming life in thatvastareabetween thesurfaceand thebottomaswellasanimalsthatburrowintothemud.Itwaseasytoderiveaskewedideaofwhat lived down below if you knew onlywhatwas subsisting on the bottom,unabletowalkorswimawayfromthedredge,andwastherightsize(neithertoolargenortoosmall)tobecaughtinthetrap.Onlywiththeintroductionoffinermeshesandimprovedtechniquesforcapturinganimalsjustbelowandabovethebottom,alongwiththedevelopmentofspecialboxesthatmaintainthepressureatdepth,havetherealsecretsofdeep-sealifestartedtobeunraveled.ButForbeswasclearlyaheadofhistime.

Themantleofthedeep-seacirrateoctopod(Stauroteuthissyrtensis),alsoknownas the glowing sucker octopod, extends almost to the tips of the arms. There,sensitive hairlike appendages called cirri feature reduced suckers withphotophores that can glow steadily or flash on and off to attract prey.Distinguishedby two finson itsheadandan internal shell, thecirrateoctopusbelongstooneofthetwooctopussuborders.

Forbeshadattractedmanysupporters.Still,eventhosewhomightallowforsomeprimitiveorancientlifeinthedepthscouldnotimaginethetrueextentoflifethere.

Forbeswentontohaveadistinguishedcareerasacuratorandpaleontologistat theMuseumof theGeologicalSocietyofLondon.HewasalsoprofessorofbotanyatKing’sCollege,London,andprofessorofnaturalhistoryattheRoyalSchoolofMinesandtheUniversityofEdinburgh,whereheworkedonhisbookNatural History of European Seas, one of the first general studies ofoceanography.Unfortunately,Forbes died in 1854 at the ageof 39.His book,which included theazoic-zone idea,waspublishedfiveyearsafterhisdeath—thesameyearDarwinpublishedOn theOriginofSpecies.HadForbes livedalittle longer, he would have seen his theory soundly quashed by Sir CharlesWyville Thomson, whose expeditions on the HMSPorcupine (1869) and theHMSChallenger (1872–76)changedtheideaofwhatcouldlivein thedepths.Thomson even managed a sounding in the Mariana Trench. Yet Forbesstimulatedinterestindeep-searesearch,andhiszonesforeshadowedlaterworkandunderstandingofthebiogeographyofthesea.Even in Forbes’ lifetime, various accounts hinted at life below his self-

imposed1,800 feet (550m).AnddespiteThomson’swork,many still thoughtthatspecimenspulledupfromthedeephaddied insurfacewaters,sunkdownandbecomeentombed,beyondthereachofdecay.Thenumberofspeciesfoundatgreatdepthat that timewouldseemtoargueagainst this.But facts traveledslowlyinthosedays,andintheabsenceofpersonalexperienceoroverwhelmingproof, people believed what they wanted to believe. Hailing from a leadingcenter of scholarship, Forbes had attracted many supporters. Still, even thosewho might allow for some primitive or ancient life in the depths could notimagine the true extent of life there. Yes, many deep areas are anoxic, oroxygen-poor, but despite the lack of light, the persistently cold (though notfrozen)waterandtheextremepressure,theseaisfilledwithlife.Supposewecould sit in aboat and lowera cable carrying the latest iPhone

mounted within a spherical underwater housing. The iPhone’s video camerawould be capable of panning a full 360 degrees, with lights to illuminate thesubjectandfillintheshadows.Ourcameraisimaginary,buttheideaofitisnot

far-fetched. Low-budget marine researchers use “pole cams”—underwatercamerasmounted on long poles—to film below the surface. To document theCensusofMarineLifeinitsfilmOceans,GalatéeFilmsworkedin50locationsaround theworld, towinga torpedocamera that jettedalongwithswimmersat15knots.Ofcourse,theintensepressuresofthedeeplayerspresentachallengeto sampling at depth, but the technology exists. The hypothetical expeditiondescribedbelowoffersoneexampleofalongtriptotheoceanbottom,althoughweshouldalwayskeepinmindthatnotwojourneyswouldeverbethesame.Let’scallourimaginedcamerathe“iMonstercam.”IfouriMonstercamcould

descendtothebottomfootbyfoot,layerbylayer,whatwoulditsee?Wecouldbait thedevice toguaranteesomeaction,asNationalGeographicor televisionproducers on a deadlinemight do, but thatwouldprejudiceour search towardbloodthirsty predators. Let’s try for a truer picture. Our iMonstercamattachmentsmightincludeahydrophone,orunderwatermicrophone,tohearandrecordwhat’sgoingoninthesea.TherewouldalsobeatinyacousticDopplersensor to gauge the speed anddirectionof the currents, aswell as sensors formeasuringwaterconductivity,temperatureanddepth.

Nearthesurface,thedeep-seacombjelly(Beroecucumis)istransparent,butdeeper-dwellingspeciesturnred,aneffectivecamouflagewherethereisnoredlight.B.cucumisisanactiveswimmingctenophore,usingtherowsofcombplatesalongitsbodytomovethroughthewater.Itcanalsoproducespeedburstsbysquirtingwaterfromitsmouth.Thecombjellypreysonotherctenophores,swallowingthemwhole.

Aftersurfacingandspoutingseveraltimes,ahumpbackwhale(Megapteranovaeangliae)divesdeepinCalifornia’sfood-richMontereyBayinSeptember2013.

V

SurfaceWaters

TheEpipelagic(Euphotic)Zone

Surfaceto660feet(200m)

ISUALcreatures thatweare, the first thingwenoticewhenweslipbeneath the surface is thedrop in light; it’s likegoing indoorson abright, sunnyday.The iMonstercam,with itseyelike lens, reactsby

openingthelenstoletinmorelight.Typically,atjustthreefeet(1m)belowthesurface,55percentofthelightfromthesurfaceisgone.At33feet(10m),theredportionof the lightspectrumisswallowedup,as is84percentof the lightfromthesurface.Bythetimethedevicereaches330feet(100m),99percentofthelightfromthesurfaceisgone.Thecolorspectrum,exceptforbluelight,alsodisappears.Butlightpenetrationvariesconsiderablyaccordingtolatitude,timeof year and water clarity from particles and suspended sediment. In coldplankton-rich temperate water in summer, when the water is thick with theselivingparticles,adivercangofromnoontotwilightinamatterofafewfeet.Inthetropics,withahighlyreflectivesandybottom,thesamedepthcancarry50percentmorelightfromthesurface.Perhapsnothingevokesthevisceraltransitionfromairtowatermorethanthe

abruptchangeinthesoundscape.Ashumanstaketheplungefromairtowater,ourearsseemtoshutdownasthewaterpressesin—wearerenderedmostlydeafby this sudden transition.Butmanyanimals that liveunderwaterhaveadaptedanotherway of hearing known as bone conduction,whereby the bones of theanimal’sskullpickupthepressurewavesofsoundtravelingthroughthewaterandrelaythemtotheinnerears.Asthe iMonstercam’shydrophoneswitcheson,pickingupacousticpressure

wavesinthewater,webecomeawareofanotherworld.Thefirst200feet(60m)below the surface sounds staticky, like the white noise of some 20th-centuryexperimental music. Then we hear faint rumbles and occasional whistles andcries.Coulditbewhales,dolphins,strangefish?Andthentherumblinggrows

louder.Thehydrophonestartstopickupabackgroundwhiningsoundthatincreases

steadily,eventuallyobliteratingthewhistlesandcries.Thisisthenoiseofshiptraffic.InLeonardodaVinci’sday,youcouldputatubeintothewaterandhearthesoundofasailingshipmovingthroughthewatermilesaway.Today,oceantrafficcomprisessome50,000containerships,aswellasferries,cruiseshipsandthenaviesoftheworld.Thefastertheygo,thenoisiertheyare.Onlysubmarinesandsailboatsare“quiet.”Giventheextraordinarylevelofsoundgeneratedinthesurfacewaters in someareasof theworld,youmight aswellbe indowntownManhattan,ManilaorMexicoCityatrushhour.Soundtravelsnearly4½timesfasterandroughly100timesfartherunderwater

than it does in the air, dependingonwater conditions, depth and the loudnessand frequency of the sound. Low sounds travel farthest, while high-pitchedsounds don’t travel much distance before dissipating. The physics of soundunderwater is a matter of great interest to whales, dolphins and other marinemammalsthatusesoundtofindtheirfoodandmatesandtocommunicatewithoneanother.Visibilityunderwater,evenintheclearesttopmostlayer,islimitedtoa fewdozenfeet.For fast-moving,wide-rangingmarinemammals, sound isthetoolofchoice.Theabruptair-watertransitionisalsomademanifestbytheabsenceofwaves

and the rockingof thesea.Just10 to14feet (3–4m)belowthesurface,all iscalm.Infact,thereissomemovement—massivesurface-watercurrents—butwearebeingcarriedalongat thesameslow,steadyspeedaseverythingelse.Thesurfacecurrentstypicallytravelatthreetofivemilesperhour(5–8km/h).Theclassic schoolchild example of an ocean surface current is the Gulf Stream,whichrangesfrom50miles(80km)wideoffMiami,Florida,to300miles(480km)wideoffNewYorkCity,withadepthof2,100feet(640m).TheGulfStreamhasbeendescribedasariverinthesea,andthevolumeof

movingwaterrepresentsmorethanalltheworld’sriverscombined.Ittransportswarm water from the subtropics of the Gulf of Mexico northeast across theNorth Atlantic, where part of the Gulf Stream becomes the North AtlanticCurrent,whichanglesuptowardGreatBritainandwesternEurope.Someofitbranches off toward Norway, while the rest turns clockwise back toward theequator. In the late18thcentury,BenjaminFranklin traveled regularlybyshipacross theAtlanticOceanondiplomaticbusiness andbecame intriguedby thephenomenonof theGulfStream.Even then,Europeanshipcaptainsknew thatwhencrossingtheAtlantictotheNewWorld,theyfirsthadtosailsouthtowardtheequatorbutcouldtakethemoredirectroutehomeacrosstheNorthAtlantic—afast-lanetransportthatcutdaysoffthereturnvoyage.

Thesurfacewateriswheretheworldoceanandtheatmospherealternatelyclashandcoupletodrivethe

Earth’sweather.Itcancarrygreatwarmth,thesoupoflife,aswellasthemakingsoffiercestorms.

Surface currents, found throughout the world ocean, are constantly on themove. In the North Pacific, the Kuroshio (“black tide”) travels from thesouthwest to thenortheast,moving fromJapan to thePacificCoastofCanadaand Alaska before turning south along the coast of North America andcontinuing around clockwise along the equator. In the southern hemisphere,however, the large surface-water transports move in a counterclockwise gyreacrossthebroadexpanseoftheSouthPacific,SouthAtlanticandIndianoceans.These motions are the result of Earth spinning on its axis, producing the so-calledCorioliseffect,whichcausesbothwindandwatercurrents tomoveinaclockwisedirectioninthenorthernhemisphere,graduallyflowingoutandawayfrom the equator, and in a counterclockwise direction in the southernhemisphere.Theeffectcanbecrudelydemonstratedbyobservingthewaywaterflowsoffawetspinningtop.As these surface waters are on the move, some of the warm, salty surface

waterflowingfromtheequatorialregiontothecoldtemperateorpolarregionsbecomesdenseorheavyandsinks,attimesmovingsorapidlytothebottomoffAntarctica,GreenlandandLabradorthatverticalcurrentscanbemeasuredinthewater. This is how the deepwaters of theworld ocean are formed. The deepwater flows slowly compared with the movement of the surface water andsometimestravelsintheoppositedirection,butafterhundredsofyears,thedeepwater eventually reaches the North Pacific—the “end of the world ocean”—whereitrisesagaintothesurface.Bythetimethewaterreachesitsstartingpointin the system, something on the order of 1,000 years has elapsed. Theworldoceanisthusonesystem,andallthewaterflowsthroughit.Thisisreferredtoasthermohaline circulation, because the water currents are driven largely bychangesinthetemperatureandsalinity,orsaltcontent,ofthewater.The surfacewater iswhere theworld ocean and the atmosphere alternately

clashandcoupletodrivetheEarth’sweather.Itcancarrygreatwarmth,thesoupof life, as well as the makings of fierce storms. It is the meeting place and

feeding ground for millions of seabirds, fish, whales, dolphins, seals and sealions.It’stheskinoftheworldocean—asortofupside-downSerengetiPlain.Itis the epipelagic zone, a who’s who of sea life familiar to all. These are theworld’shigh-profileoceanorganisms.A tour of the surface waters reveals an extraordinary diversity of fish and

invertebrates that accompany the better-known “sea monsters.” Many sharks,includingthewhite,oceanicwhitetip,blue,hammerheadandtiger,feedmainlyinthiszone,althoughothersharkspecieslivedeeperorarecapableofdivesfarbelowtheepipelagiczone.Bigrays,suchasthemantaray,spendconsiderabletime in this surface zone. Complicated jellyfish and siphonophores with theircolonial lifestyles, including thedreadedPortugueseman-of-war,alsoresideatthe surface, as they float andwait forwhatevermight drift by.Of course, thewhales,dolphins,porpoises,sealsandsealionsspendmostoftheirtimeinthesetopmostsurfacewaters.Someofthemhuntforfishandsquidindeeperwaters,butmosttravelthroughsurfacewaterstheirwholelives.Killerwhales (Orcinusorca) on theprowl sometimesuse the surfaceof the

seaasawall againstwhich to trap theirprey.Hunting inpacks, transient-typekillerwhalesquietly station themselves in theMontereySubmarineCanyon, afewmilesoffshoreofPointPinos,California.Unsuspectingyounggraywhales(Eschrichtiusrobustus)aswellasvariousdolphins,elephantsealsandsealionshave nowhere to hide when crossing this deep-water open area. Every April,graywhalemotherswiththeirrecentlyborncalves,measuringupto20feet(6m)long,migratenorthalongthecoastofBajaCaliforniatoAlaska.Thecalvesmaystillbenursing,buttherewillbenosolidfoodformotherorbabyuntiltheyreachfarnorthernwaters.Afteracomfortablejourneynudgingnorthalongtheshallowsofthesouthern

California coast, the grays approach Monterey. There, they must make adecision: tocross thedeepopenwatersor take the longer routeclose to shorethrough the kelp beds. Each year, a few graywhalemothers and their calveselecttocrossthisdangerouspassage,takingtheshortcutthatrisksacoordinatedattackbykillerwhales.Swimmingupfrombelow,thekillerwhaleschargethecalf, which is roughly their individual size. They attempt to corral the younggray, keeping him from his mother and preventing him from diving deep toescape.Thekillerwhalesdonotattackthemuchlargermother,thoughshemaytry to defend her calf. Some calves escape, but more often on a typical late-spring afternoon, the waters across the surface of the Monterey SubmarineCanyonbegintoturnred.Withinafewminutesorhours,itisallover.The reason so much life congregates here is because the sunlight that

penetrates the uppermost layers drives the photosynthesis of plant plankton,

whichinturnprovidesthebasisformostlifeinthesea.Thesurfacewatersarealsoknownastheeuphoticzone,fromtheGreekmeaning“welllit.”Astheskinofthesea,thiszone—thetop660feet(200m)—representslessthan5percentofthe world-ocean volume, but it is crucial to life down below.Many deep-seaanimals spend their larval lives feeding in surfacewaters, and even as adults,somestealtothesurfaceatnightonfoodraids.Thesinkingcarcassesofravagedanimalsandotherdetritusnourishtheanimalsofthemidwatersanddeepoceanbelow,helpingtomakelifepossibleintheseregions.Intheworldocean’ssurfacewaters,thediversityofspeciesandthedensityof

life are patchy yet extraordinary. The abundance depends on phytoplanktonconcentrationsthatsupportalmostalllifeinthesea.Theseconcentrationsvaryconsiderably throughout the ocean, depending on latitude and timeof year. Incertaintropicalorsubtropicalregions,suchastheSargassoSeaandpartsofthecentralPacific,concentrationsarelow.Ingeneral,thephytoplanktonisdensestinsummertowardthepolesandespeciallynearcontinentalshelvesandinareasofupwellingcurrents.Thisoverviewpresentsthepicturewithbroadbrushstrokes;muchworkmust

still be done beforewe understand the patchiness of phytoplankton at smallerscales.Without anunderstandingof thesebasic life-forms,we cannever fullygrasp the abundance,diversity andmovementsof the larger animal life-forms,includingtheso-calledseamonsters.Fromthetimeofthefirsthumans,therehasbeenconsiderablecuriosityabout

thetoplayeroftheocean.Ourforebearsmayhavemadetheirinitialforaysintothesea,inpart,toevadelargenonswimmingpredators.Justaslikely,theymayhavewaded in simply toexploita readysourceof food—fish,crabsandotheraccessible sea life—having exhausted the intertidal supply of clams, oysters,musselsandotherdelicacies.

Usingsuchbreathingmixtures,experiencedscubadiverscanreachdepthsofabout500feet(150m).Toventuretotheedgeoftheepipelagiczoneandtrulyglimpsethedarkblueworldbelow660feet(200m),

however,itisnecessarytousesubmersibles.

Primitive underwater vehicleswere first launched in 1620 and, formost of

threecenturies,spentalltheirtimeintheepipelagiczone,thedownwardlimitsofwhichwere forbidding tohumansandmachinery.With the inventionof theself-contained underwater breathing apparatus (scuba) by Jacques-YvesCousteau and Émile Gagnan in 1943, untethered divers began to penetrate todepths of 150 feet (45 m) or more. Pearl and sponge divers, who carry nounderwaterbreathingdevices,havebeenreportedtoreach100feet(30m),butnormally, they descend no deeper than 40 feet (12 m). The usual mix ofcompressedairandoxygenlimitsscubadiverstoamaximumdepthofabout250feet (75 m), although any time spent at such a depth requires a lengthydecompressionasthediverreturnstothesurface.Anydeeperandthenitrogeninthe breathing mixture, which is part of the compressed air, dissolves in theblood, producing intoxication by obstructing the blood’s ability to transportoxygentothebrain.So-callednitrogennarcosisoftenhasfatalconsequences.Toreplacenitrogeninthebreathingmixture,oxygencanbecombinedwithheliumor hydrogen, both of which are less soluble in human tissues. Using suchbreathingmixtures,experiencedscubadiverscanreachdepthsofabout500feet(150m).Toventuretotheedgeoftheepipelagiczoneandtrulyglimpsethedarkblueworldbelow660feet(200m),however,itisnecessarytousesubmersibles.Aswe lower the iMonstercam, the pressure steadilymounts.At 33 feet (10

m), thepressure is29.4poundspersquare inch(psi), twice thatat thesurface,but at 330 feet (100 m), it reaches an intense 147 psi (10 times the surfacepressure,or10atmospheres).Atthisrelativelymodestdepth,the147-pound(67kg)weightofthewatercolumnpressesdownoneverysquareinchofadiver’sbody.Three hundred feet (90m) is only halfway through the surface layer, but it

markstheusuallimitofthewind’seffectonthesea.Below330feet(100m),wearenolongercarriedalongonthesurfacecurrents.Thewaterbelow,however,retains its own unique and identifiable character, or flavor, as oceanographersput it. It has a different temperature and salinity and canmove at a differentspeed, often slower, and even in a different direction. But it is usually thecalmer,morestablepartoftheepipelagiczone.Foreveryadditional33feet(10m),weaddanotheratmosphereofpressure.

At660feet(200m),wherethesurfacelayergiveswaytothemesopelagiczone,thepressureisanuncompromising294psi(20timesthesurfacepressure,or20atmospheres),whichwouldeasilycrushouriMonstercamifwehadnotfitteditwithaspecialhousing.As the iMonstercam reaches the lower limit of the surface waters, it

encounters an extraordinary sight: “ocean snow.” The camera light captures ablizzardofnutrients,wasteproducts,deadplantandanimalpartsandeven the

oddcarcass.Everythingthatdoesn’tgetswallowedenrouteasitheadsthroughthemiddlelayersoftheseaisdestinedfortheverybottom.Thisconstantsnowbecomesmostpronouncedatcertaintimesoftheyear,especiallyfollowingtheproduction of phytoplankton in cold-temperatewaters. And in order to see it,you must look up toward the light directly overhead or depend on theilluminationofartificiallights.

♦

InthesurfacewatersoffHawaii,afalsekillerwhale(Pseudorcacrassidens)snatchesamaturemahimahi,alsoknownasdorado(Coryphaenahippurus).

Typicalofpredatormammals,thekillerwhale(Orcinusorca)hassharpvisionandisadeptathuntingaboveandbelowtheseasurface.TwoAntarcticorcasspyhoparoundaWeddellseal,decidingwhethertotiptheicefloeormakewavestowashthesealintothewater.

Akillerwhale(Orcinusorca)cornersayounggraywhaleinMontereyBay,California.Everyyearduringthegraywhalemigration,transientkillerwhalessingleoutandtrytoseparategraywhalecalvesfromtheirmothers.

VariouslyknownasMurray’sabyssalanglerfish,theblackdeep-seaanglerorthedeep-seablackdevil,Melanocetusmurrayilivesthroughouttheworldocean,exceptaroundthepoles,stayingatdepthsof3,000to20,000feet(900–6,000m).Theindividualshownhereisafemale.

B

MiddleWaters

TheMesopelagic(Disphotic)Zone

660feetto3,300feet(200-1,000m)

LUE and more blue, ever darker. It is not “aphotic” (no light) but“disphotic” (away from the light). Throughout much of this zone,depending on conditions above, blue lightmay barely illuminate the

creaturesthatinhabitthistwilightzoneofperpetualbluegloom.Fromthebright,colorful fishwith theirdramaticcountershading(lightbellies,dark tops) foundin surfacewaters,webegin to see fish that areuniformly silver-grayorblack.Butwhilethefishbecomedarkerandmoremysterious,theinvertebratesseemtoturn brighter andmore colorful.Manymidwater jellyfish are dark purple, andcopepods,mysids,shrimpandothercrustaceansturnbrightorangetodeepred.The purples, reds and oranges of the invertebrates aremostly invisible in thenarrow band of blue light from the surface and the primarily blue light frombioluminescence. The camouflaging silver-gray to black coloring of the fishhelpsthemavoiddetectionbypredators.AstheiMonstercamdescends,thelightandtemperaturechangesarealmostimperceptible.Nowittakeshundredsoffeetbeforethelightfadesonlyhalfacameraf-stopandthewatertemperatureslipsyet another degree. Still, the pressure continues to mount at a furious,unrelentingpace.From660to3,300feet(200–1,000m),thepressureadvancesfrom20timesthesurfacepressureto100times—upto1,470pounds(670kg),nearlythree-quartersofaton,pressingoneverysquareinch.Thepressureofthemiddlewaters,orlayers,presentsthebiggestobstacleto

humanexplorationofthiszone.ThefirsthumanstoexperiencewhatlifeislikeherewereAmericansWilliamBeebe,ageologist-explorer,andOtisBarton,aninventor-engineer,whopenetratedthemesopelagiczoneintheirbathysphereinthe late 1920s and early 1930s. Itwas an ideal partnership, asBarton had thetechnical expertise to design and build a vehicle that could get intowhatwasthenconsidered“thedeep”andbackinonepiece,nomeanfeat intheearlyor

eventhelate20thcentury.

Allcontactwiththesunwaslost.Butitwasn’tjustallblack.Albeitintenseandpervasive,theblackwasonly

thebackground,andallwasforgottenwhenonemonsteroranotherloomedintoview.

Beebe, who couldn’t drive a car but was determined to copilot thebathysphere, had sketched designs for a few cylindrical deep-sea vehicles,keepinginmindthepilots’comfort.ButBartonknewthatthevehiclehadtobesmall and spherical,with1¼-to1½-inch-thick (3–4cm)wallsmadeof single-cast,first-grade,open-hearthsteel.Theinsideofthespherewasjust4½feet(1.4m) in diameter and could be entered only by crawling through a 14-inch-diameter(35cm)hatch.Ontheirseconddive,14feet(4m)ofinch-thick(2.5cm)telephonecablethat

linkedthebathyspheretothesurfacecameshootingintothespherelikeagiantsquidtentacle.BeebeandBartongottangledupintheequipmentandhosesandevenwitheachotherinthecold,clammysteelcrawlspacethatwasthecapsule.Onanotherdive,waterstartedtricklinginthroughthedoorseal,andBeebehadto call the surface and ask that the bathysphere be lowered quickly. Theadditionalpressuresealed thedoor,as theyhadhoped.Once,onanunmanneddescent,thesealsfailed,andwhenthecraftwaspulledtothesurface,theheavydoorshotacrossthedeckwiththeforceofacannonball.Eventually, after some of the deep dives, the two six-inch (15 cm) quartz

portholes failed pressure tests and had to be scrapped. Venturing deep was arisky business.Yet despiteBeebe’s technical failings in some areas, hewas afearlessdiverandaveteranexpedition leaderaswellasagreatproponentandpopularizerofsciencewhocouldraisemoneyforimaginativeprojectsandthenchronicleitallinpurepoetry.Beginninginthelate1920sandpersistingthroughtheearlyyearsof theGreatDepression,BeebeandBartoncompletedsome26descentsinthe“tank,”astheycalledthebathysphere,becomingthefirsthumanstoglimpsethemiddlelayersandtopenetratetotheirverylimit.Ina1934diveoff Bermuda, they reached 3,028 feet (923m), beating their own records andpenetratingfive timesdeeper into theocean than thepreviousrecorddepthforhumans. At the greatest depth, Beebe experienced “the cosmic chill and

isolation, theeternal andabsolutedarkness,”butmuchof thedescentwas justbluegrowingeverdarker:“Thebluewhichfilledallspaceadmittednothoughtofothercolors.”Thelastglimmeringofgraylightat1,900feet(580m)fadedtopitch-blackby

2,000feet(610m),andallcontactwith thesunwaslost.But itwasn’t justallblack.Albeitintenseandpervasive,theblackwasonlythebackground,andallwasforgottenwhenonemonsteroranotherloomedintoview.Asingleelectriclighthelpedilluminatesomeofthecreaturesastheyslippedinfromthedarknessto inspect the vehicle, but it was mainly the animals’ bioluminescence thatrevealed the creatures to Beebe. Everywhere he looked on his various dives,he witnessed “the flash of long fangs” and “the passing of dozens of brightlights”corresponding tomultiple fish.Somefish less thana foot (30cm) longmightcarryhundredsoflights.Beebe’sobservationsondivesat1,600to2,200feet(490–670m)includedan

encounterwhere he “watched one gorgeous light as big as a sixpence comingsteadilytowardsmeuntil,withouttheslightestwarning,itseemedtoexplodesothatIjerkedmyheadbackwardawayfromthewindow.”Thecreaturehadstrucktheglass,andthelighthadintensifiedatthepointofcontact.Later,Beebesawthe illuminated outline of a never-before-seen deep-sea fish that suddenlydisappearedas it turned towardhim,althoughhesensed itsmawwasopening.Atthesamedepth,asightingoftwosix-foot-long(2m)fish,“thegeneralshapeofbarracudas”andlargerthanthebathysphere,morethanadequatelyarguedthecase for seamonsters, evenwithout a precise identification.The fish hadpalebluish lights all along their bodies, like the illuminated portholes of an oceanlinerplyingtheseaatnight.Beebealsoreportedahuge“undershotjaw...armedwithnumerousfangs[and]twolongtentacleshangingdown,eachtippedwithapairofseparate, luminousbodies, theupperreddish,theloweroneblue.Thesetwitched and jerked along beneath the fish.”Themouth of one fishwaswideopen.BeebecalledthefishBathysphaeraintacta—“theuntouchablebathyspherefish.”Onthebathysphere’shistoric3,028-foot(923m)descent,Bartonlargelytook

care of the camera while Beebe used his eyes to see what, in many cases, acameracouldn’tcapturebecauseofthelimitedlightandfieldofvisionandthelimited technology of the time.Of course, Beebe could collect no samples todissectandassigntoaclass,family,genusorspecies.Justtoviewtheoutlinesofacreatureoreven togaze into itseyesandmouth isnotconsideredenough toassignitaspeciesname,andBeebe’sdescriptionsweresofantastic, theywerenot believed by some. However, Beebe worked closely with a professionalillustrator, who drew from his detailed descriptions, oftenwithin hours of his

returntothedeckoftheship.SomeanimalsBeeberecognizedfromactualdeep-seaspecimenshehadpreviouslyseenandstudied.ManyanimalswereonlybarelyseenorweretoostrangeforBeebetoattempt

todraw,muchlessname.Oneofthese—thebigonethatgotawayonhisrecorddive—involvedamassive, colorless20-foot-long (6m) fishat2,450 feet (747m).Beebemissedthefaceaswellas thefinsof thebehemothasitglidedintoandthenimmediatelyoutofview.HecalledforBartontocheckitout,butbythetimeBartonlookedthroughhisporthole,thecreaturewasgone.Beebeleftitat that. Most of his descriptions fit creatures that we know today inhabit themiddlelayers,justwherehesawthem.Hispowersofdescription,floridastheysometimes were, did not oversell the bizarre qualities of the creatures heencountered, althoughhedidoccasionally comeup shortwith suchphrases as“indescribablebeauty.”Healsosampledthedeepmorethan1,500times,usingnets and other contraptions, and caught more than 115,000 specimensrepresenting at least 220 species ofmidwater life.The condition of deepwaterspecieswaspooroncetheywerehauledtothesurfacewiththesecrudesamplers,yet many of the species had never been seen or examined before, bloated orskinned,deadoralive.Beebe’s “untouchable bathysphere fish” turned out to be a new species of

dragonfish.Other fish described byBeebe, such as the viperfish and the littledevilfish,canbepositivelyidentifiedthroughhisillustrations.ThelittledevilfishisnoneotherthantheanglerfishMelanocetus,whichtypicallygrowssixincheslong (15 cm). Our iMonstercammeets several of these poster fish—the post-Jaws sea monster in miniature—with its long, sharp teeth resembling slendershardsofglass,eachtaperingtoaneedlepoint.Whenthisbrightorangedeep-seafishmadethecoverofTimemagazineonAugust14,1995,thedeepseacanbesaidtohavereachedtheforefrontofmasspublicconsciousnessintheUnitedStates,atleastforafleetingmoment,eventhoughBeebehaddonesomuchtopopularizesomeofthesamecreatures60yearsearlier.AsBeebeandBarton’sbathyspheredescended,itdisturbedthewater,causing

muchof thebioluminescence theywitnessed.Yethere, too,Beebemadesomestartling observations.He claimed that he could distinguish various species oflantern fish according to the patterns of light they displayed. Indeed,we nowknowthatwithinthelanternfishgenusDiaphus,thereareatleastfivedifferentbioluminescentpatternscorrespondingtospecies,andmost lanternfishspeciesinothergeneraalsohaveuniquepatternsofphotophores.Bioluminescence is simply light that originates from living animals and

plants. Found to some extent in surface waters, bioluminescence is used bynearly70percentofmesopelagiccreatures,but itsusetapersoffrapidlyin the

deeperwaters below themesopelagic zone. Thesemiddle layers represent themainbioluminescentbiomeonEarth.Ifyoucouldgoanywhereintheworldtowitnessorresearchbioluminescentlightshows,thiswouldbetheplace.Bioluminescence is familiar to many as the light emitted by fireflies and

glowworms. Relatively rare on land, bioluminescence is almost unheard of infresh water. But those who have sailed or canoed in the sea, especially onmoonlessnights,willhaveobservedagloworsparkleinthewater.Inthiscase,themovement—whether froma boat sailing through thewater or fromanoardipping into thewaterora seal swimmingnear the surface—usuallyemanatesfromthedisruptionofthousandsofphytoplanktoncalleddinoflagellates.Duringa “red tide” dinoflagellate bloom, blue streaks in the water at night can bestimulatedbywavescrashingonabeachandarebrightenoughtophotograph.Deepunderwater,bioluminescenceisevenmorespectacularbecauseofthedarkworldinwhichitoccurs.It isalsomuchmorevarious,bizarreandalluring.Inthis otherwise gloomy environment, an astonishing diversity of species,includingfish,squidandjellyfish,haveevolvednumeroususesforlight,suchasdefense,communicationandsurpriseattack.Many deep-sea creatures use bioluminescence as a defensive reaction

designedtostartlepredators(the“boo”effect)ortoblindthemtemporarily(the“flashbulb”effect).Thearrangementoflightsisconfusing,soapredatordoesn’tknowwhichendofthepreytochase.Alternatively,lightsontheundersideofananimalmayactascamouflageagainst thesparkleof lightcomingfromabove,withthesameeffectthatawhitebellyhasnearthesurface.

Allcontactwiththesunwaslost.Butitwasn’tjustallblack.Albeitintenseandpervasive,theblackwasonly

thebackground,andallwasforgottenwhenonemonsteroranotherloomedintoview.

Deep underwater, bioluminescence is evenmore spectacular because of thedarkworldinwhichitoccurs.Itisalsomuchmorevarious,bizarreandalluring.In this otherwise gloomy environment, an astonishing diversity of species,includingfish,squidandjellyfish,haveevolvednumeroususesforlight,suchasdefense,communicationandsurpriseattack.Bioluminescence is also used for communication among individuals of the

samespecies.Ithelpsmembersofsomespeciescomeorstaytogetherandcanbe important for findingandsignalingone’s readiness tomateandattractingamate. Researcher Edie Widder of the Ocean Research & ConservationAssociation in Fort Pierce, Florida, has dedicated her career to learningmoreaboutbioluminescenceintheseaandemployingsciencetoreversethetrendofmarineecosystemdegradation.Sheconfessesafascinationforthe“languageoflight.”Some researchers think itmaywellbecomparable to a spokenor sunglanguage—asrichandcomplexasisthenumberofspeciesthathaveevolvedtouseit.Thoselinguisticmysteriesarestillatanearlystageofbeingunraveled.InWidder’sTEDtalk in theGalápagosIslandsinApril2010,sheexplained

thatthefirsttimeshewentdownto880feet(268m)inaspecialWASPdeep-seadivingsuitandturnedoutthelights,“Iwastotallyunpreparedforhowmuchbioluminescencetherewasandhowspectacularitwas.Isawchainsofjellyfishcalled siphonophores that were longer than this room, pumping out so muchlight that Icould read thedialsandgauges inside thesuitwithouta flashlight,and I saw puffs and billows of what looked like luminous blue smoke andexplosionsofsparksthatwouldswirlupoutofthethrusters—justaswhenyouthrow a log on a campfire and the embers swirl up, but these were icy-blueembers.Itwasbreathtaking.”

Inrelationtoheadsize,theteethoftheSloane’sviperfish(Chauliodussloani)areamongthelongestofallfishspeciesandareusefulforimpalinglargeprey.C.sloanitypicallygrows8to14inches(20–35cm)long.ThisspecimenwasfoundoffthePortuguesecoastatadepthof2,600feet(800m).

Afemaledeep-seaanglerfish(Himantolophuspaucifilosus)displaysthebioluminescentlure,or“fishingpole,”thatgrowsoutoftheforeheadofthisspeciesandisusedtoattractprey.Anglerfishcanbecharacterizedbytheirluresandbytheuniquecomplexstructuresthatproducebioluminescence.

Thecrystaljelly(Aequoreavictoria)isthehydrozoanjellyfishwhosebioluminescenceintriguedresearchersandledtothedevelopmentofthegreenfluorescentprotein(GFP)moleculeusedasatracerincellbiologyandgeneticwork.In2008,theNobelPrizeinChemistrywasawardedtothethreescientists

whoharnessedGFPforwidescientificuse.

Overtime,Widderhasbecomesofamiliarwithbioluminescentcreaturesthatshe can identify many animals by the type of flashes they produce. She hasworked with computer-image-analysis engineers to develop automaticrecognition systems to identify flashing animals and extract the precisecoordinates.Thisapproachmatchesthesortofstudiesthatecologistsdoonland.“Most of the people studying bioluminescence today,” says Widder, “are

focused on the chemistry, because these chemicals have proved so incrediblyvaluable for developing antibacterial agents, cancer-fighting drugs, testing forthe presence of life onMars and detecting pollutants in ourwaters.” The lastapplication is theone thatWidder spendsmoreandmoreofher timeon thesedays.In2008,theNobelPrizeinChemistrywasawardedtoOsamuShimomuraof

theMarineBiologicalLaboratoryatWoodsHole,ColumbiaUniversity’sMartinChalfie andRogerY.Tsienof theUniversityofCalifornia,SanDiego for thediscoveryanddevelopmentofthegreenfluorescentprotein(GFP).In1962,thismoleculewasisolatedfromthebioluminescentchemistryoftheso-calledcrystaljelly(Aequoreavictoria),ahydrozoanjellyfishusuallyfoundoffthewestcoastof North America. Because of the profound impact this molecule has had onresearchintocellbiologyandgeneticengineering,Widderandothersequatethisworkwiththeinventionofthemicroscope.With the aid of GFP, researchers have devised ways to watch invisible

processes such as howcancer cells spread andhownerve cells develop in thebrain.DrawingonDNAtechnology,researcherscanuseGFPasataggingtool,connectingittothousandsofotherwiseinvisibleproteinsinlivingorganismstofollowtheirmovements,positionsandinteractions.Widder tells of a neuroscience experiment inwhich researchersmanaged to

tagvariousnervecellsinamousebrain,producingaboldarrayofcolors.Whatsoundslikeapartytrickcanbeavaluabletool.Bioscienceisseekingtomaptheroleofvariousproteinsinthebody,asthey

control important chemical processes. When the protein machinerymalfunctions, illness and disease often follow. Using tagging, researchers canfollow the fate of various cells, for example, to learn how nerve-cell damageoccurs during Alzheimer’s disease or how insulin-producing beta cells arecreatedinthepancreasofagrowingembryo.Theallureof light isacommon theme inbiology.Sincebioluminescence is

suchafundamentallyusefultoolinthemiddlelayers,biologiststhinkthatitmayhaveevolvedmanyseparatetimes.“Atleast40distinctlight-emittingchemicalsystems occur among bioluminescent organisms,” says James G. Morin, anauthorityonbioluminescenceatCornellUniversity, inIthaca,NewYork.“Yet

inonlyabouteightofthesearethechemicalconstituentscompletelydeterminedandthereactionfullyunderstood.”Most of the animals that have been studied make their own light using

elaboratelight-producingorganscalledphotophores,whichoccuracrossawiderange of fish, squid and other invertebrates.The simpler photophores utilize aseriesofglandlikecellstoproducethelightthroughachemicalreaction.Theseare surrounded by a kind of screen of black pigment cells. More elaboratedesignsforphotophoresincludecolorfilters,adjustablediaphragmsofpigmentcells,flapsofskintoturnthelightonandoffandlensestofocusthelight.Thephotophores of certain squid species, for example, are coveredwith layers ofskin containing chromatophores, which allow them to alter the color andintensityofthelight.Othercreaturesthatproducebioluminescencerely,instead,onasymbioticrelationshipwithcertainbacteriatomakelight.Theadaptationsfor this type of communication and hunting include, of course, the eyes thatperceive this kind of light. Most bioluminescence is blue because blue lighttravels farthest throughseawaterand isoptimal forcommunication.Thusmostanimals using bioluminescence make blue light, and most can see only bluelight.Widder’sexplorationintotryingtoattractbioluminescentanimalsbeganwith

an idea for an optical lurewith 16 blueLEDsprogrammed to create differentlightshows.Shecalleditthe“electronicjellyfish.”Tovideothedeviceinactionand the reaction of animals responding to it, she developed a camera systemcalled Eye-in-the-Sea, complete with red-light illumination, which is invisible(andthusunobtrusive)tomostanimals.

Namedforthepairedlight-producingphotophoresalongitsundersideandonitshead,thefour-inch-long(10cm)lanternfish(Lepidophanesguentheri)ismorenumerousthanotherdeep-seafish.Itusestheselightstocommunicatewithotherlanternfishduringcourtshipandwhileshoalfeeding.

Thebigeyesmoothhead(Bajacaliforniamegalops)isabottom-livingmesopelagicandbathypelagicfish,typicallyroamingbetween2,600and4,600feet(800–1,400m).ThisonewasphotographedontheMid-AtlanticRidgeintheNorthAtlantic.

Thesizeofthepupilissocriticalforobtaininglightthattheeyesofsomefishareallpupil;otherpartsoftheeyehavebeendoneawaywithentirely.Onesuchadaptationfoundinseveralspeciesoffishistubulareyes,inwhicheacheyeisperchedonashort,blackcylinderwitha

translucentlensatthetop.

Widder’s TED talk featured early Eye-in-the-Sea video taken at 2,000 feet(610m)intheBahamas,showingtheresultsofthefirstexperiments.Despitetheblurry low resolution, you can see the LEDs flashing boldly in the darkness.Seconds later comes the response.On the screen, it looks like three strings ofpearls alight. The signaler is some kind of shrimp that releases bluebioluminescent chemicals into thewater in response to theelectronic jellyfish.Then other shrimp join in and start flashing. Could there be interspeciescommunicationgoingonhere?“Wedon’t knowwhatwe’re saying,” saidWidder, referring to the possible

messages emitted by the LEDs. “But the cool thing is, we’re talking to theshrimp.”Andthere’snotranslationoftheshrimp’sresponseeither,althoughthevideoshowsclearlythatthereisaresponse.“Webasicallyhaveachatroomgoingonhere,”explainedWidder,“because

onceitgetsstarted,everybody’stalking.”Dowehaveanyideaofthetopic?“Personally,” said Widder, eager to embellish the chat-room metaphor, “I

thinkit’ssomethingsexy.”Along with the flashing-light show in the mesopelagic, our iMonstercam

reveals numerous big-eyed creatures. Many of the bulging fish eyes haveyellow-tinted lenses, like sunglasses, which, for a predator, make the prey’sbioluminescencestandout.Othereyeshavelargepupilstogatherasmuchlightaspossible.Thesearenotthedeep-seaanglerfishwiththeblankexpressionsthatPixarfeaturedinFindingNemo.Theinspirationforthoseblankeyescamefromdead fish preserved in formalin. The Pixar animators probably thought theylookedscarier,buttheyjustlookeddead.Thatlookwouldn’tworkinthewild.Thesizeofthepupilissocriticalforobtaininglightthattheeyesofsomefish

areallpupil;otherpartsoftheeyehavebeendoneawaywithentirely.Onesuch

adaptationfoundinseveralspeciesoffishistubulareyes,inwhicheacheyeisperchedona short, blackcylinderwith a translucent lens at the top.Eacheyecontains two retinas,oneon thewallof thecylinder,which focusesondistantobjects, and the main retina at the base, which is designed for all-importantclose-upviewing.Theretinasofmostmesopelagicfishareadaptedtomaximizethesmallamountofavailablelight.Insteadofconesfordaylightvisionandrodsfornightvision,asinhumansandotherlandanimals,theretinasofdeep-seafishhaveextra-longrodsonly,eachpackedwithlight-absorbingpigmentmoleculesthatcandetectanarrowrangeofwavelengths.Tostudytheeyesofmesopelagicanddeep-seafish,JulianC.Partridgeofthe

University of Bristol and Ron H. Douglas of City University London, inEngland, lookedatnearly175 fish species in the late1990s. Inexamining theeyes,theresearchersnoticedrightawaythatevenintheblackestregionsofthelowermesopelagicandintheupperdeepseas,thefishhavebigeyes.Why?Andwhyaretheseeyessensitivenotonlytothemonochromaticbluelightleftfromthe downwelling sun but also to the somewhat broader range of color thatapparentlydoesnotexistinthisunderwaterworldexceptasbioluminescence?

Thelargelefteyeofthedeep-seasquid(Histioteuthissp.)ispermanentlydirectedupward.Spendingthenightatdepthsofaround1,640feet(500m),thesquidascendsduringthedaytolessthan660feet(200m),whereitusesthiseyetosearchforsilhouettesofpreyagainstthelightfilteringdownfromthesurface.Thesquid’sothereyeispointeddownwardandisadaptedtobioluminescentflashesandothersignalsofsubtlepreymovements.Thissquidaveragesaboutfourinches(10cm)longbutcanreachuptoonefoot(30cm)inlength.

Thebioluminescentbarbelofastomiatoidfish,suchasthedeep-seadragonfish(Eustomiasmonodactylus)foundinthemiddlewatersabovetheMid-AtlanticRidge,isamultipurposeappendage.Usingthebarbel,thedragonfishcanmakeitselflookbiggerandcanattractanddistractprey.Itmayevenservetohelpspeciesrecognizeoneanother.

Pursuing these and other lines of inquiry, Partridge and Douglas came to thestartlingconclusionthattheeyesofmesopelagicanddeep-seafishhaveevolvedlargely as a consequence of bioluminescence, not sunlight. Theywere able toshow that deep-sea eyes are designed to detect blue light from other animalsrather thanfromthesun,aswaspreviously thought.“Sunlightmayfuel life inthe deep sea,” explained Partridge in New Scientist, “but when it comes tovision,bioluminescenceisthedrivingforce.”Onegroupoffierce-looking,big-eyedfishresidenttothemesopelagicis the

stomiatoids,suchasdragonfish.Astomiatoidistypically6to10inches(15–25cm)long,butitsmassiveexpandingjawsarefilledwithfangliketeeththatallowittocatchandeatpreylargerthanitself.Itismostlymouthandhasonlyasmalltail for swimming.The stomiatoid’s teeth are positioned in such away that ifthisfishweretocloseitsmouthcompletely,itwouldimpaleitsownbrain.As with a number of other mesopelagic and deep-sea fish, a barbel hangs

downfromthechinofthestomiatoid.Thefishusesthisfleshyprojection,oftenbioluminescent, as a lure. A barbel may also help individuals of a speciesrecognizeoneanother.Toapotentialpredator,thebarbelmaydisguisethetruesizeandpreciselocationofthefish.Thebarbelvariesinshapeandlengthfromone species to another. It can be a short, single hairlike filament, a fleshymultiple-branchingstrandoragrapelikeorflowerlikeappendagethatotherfishperceiveasashrimporaworm.Abarbelcanmeasureupto10timesthelengthofthefish,thehighestratios

usuallyoccurring in small fish thatneed to lookbigger.Onedecent-sized8½-inch (22 cm) stomiatoid fish boasted a three-foot-long (1m) barbel. This fishmighthaveappearedasamuchlargerbig-jawedfishtoapotentialpredator.Andevenifthebarbelwereattacked,thestomiatoid—somethreefeet(1m)away—couldlungedownwardandpossiblyturnitsownpredatorintoprey.After recording so many big-eyed fish at nearly 2,300 feet (700 m), the

iMonstercampicksupamidwaterHistioteuthis squid.Litupwithapatternofphotophores,thesquidlooksasifithascontractedacaseofthemeaslesalloveritsheadanddown to its tentacles.First,we see the topof the squid,withonemassive eye cocked toward the surface. Then, as we pass beneath theapproximatelythree-foot-long(1m)creature,weglimpseitsothereye,whichistiny.With its big eye, the squid obtains a picture using all the available lightfromthesurface,whilethesmalleyepicksupand,whennecessary,respondstothebioluminescentflashesofpotentialpredators,preyormatesfrombelow.Even deeper, we glimpse the fire-shooter squid (Heteroteuthis dispar).

Measuring only three inches (7.6 cm) from the mantle (the main part of thebody) to the tips of its tentacles, this squid could easily be missed unless

disturbed. When the iMonstercam fails to show sufficient respect, the fire-shooter responds. But rather than the trademark ink used by other squid toconfuse predators, this squid expels a sudden bioluminescent cloud, a minifireworks display that gives it time tomake its getaway. Jetting off, the fire-shooterleavesustoponderthewondersoflight.Thedeeperwego,thefewerfishandsquidappear.Onecalculationestimates

anaverageofjustonefemaleanglerfishpercubicmileinthiszone.Howbigisacubicmile?It’stheamountofwaterpouringoverNiagaraFallsinamonth,saysStephenLaRocqueoftheUniversityofRegina,Saskatchewan.Alternatively,ifyouweretobuildahighwallallaroundtheislandofManhattanandpourinonecubic mile of water, only the tops of buildings higher than 23 stories wouldappearabovethesurface.Inanycase,whenitcomestolandingamate,acubicmilewouldseem tobeavastarea fora single, roughlyone-foot-long (30cm)anglerfish.Withtheincreasinglysmallernumbersofagivenspecies,itbecomescrucial for individuals to be able to search for and signal a mate using everstrangerandmoreextremebioluminescentdisplaysorotherstrategies.Oneadaptationforovercomingthedifficultiesoflifeinadimlylitworldcan

be found in various species of anglerfish. On the one hand, the large femaleanglerfishlookslikeatruemonsterofthedeep,withbigteeth,expandablejawsandcomplex lightdecorations.The tinymale,on theotherhand, looks likeanimmature sibling and is incapable of producing light. In fact, the male hashooked denticles—toothlike projections—on its snout and chin that it uses toaffixitselftothefemalewhileitwaitstospawn.In some anglerfish species, the male becomes a lifelong parasite of its

prospectivemate.Themale’sjawsandtheskinarounditsmouthfusewiththefemale’s body, leaving only a small space at the sides of the mouth for gasexchange. In time, the male’s circulatory system becomes connected to thefemale’s,andhisinternalorgansandeyesdegenerate.Thefemalebecomesthesole breadwinner, and the male, in essence, becomes a sort of nonretractablepenis.Havinga“leach”forapartnermaynotseemmuchofalifeforthefemale—orforthemaleeither—butitneatlysolvestheproblemoffindingone’smateinthedarkdepths.At 3,280 feet (1,000 m), nearly the bottom of the mesopelagic zone, our

iMonstercam begins to pick up intense clicking sounds. Sperm whales! Thesoundsaresoloud,itwouldseemthespermwhalesareallaroundus,yetweseenothing. Seconds later, the booming sounds of the calls from blue whalesprovideorchestralaccompanimenttotherhythmicclicks.This increase in sound level occurs at this depth because of special “sound

channels” in theocean. Ineveryocean, at a typicaldepthof3,280 feet (1,000

m),deep-watersoundchannelsrefractsoundwavesandareable tospreadlowsoundsacrossgreatdistancesofhundredstothousandsofmiles.Whalesdonothavetobeatthisdepthfortheirsoundstobeamplified;theirsoundscanfilterdownintothechannelandbepickedupandtransmitted,asifthroughapowerfulamplifierandloudspeaker.There is no proof that whales routinely use this channel for long-distance

communication, butwe know that sounds produced by blue and otherwhaleshavetraveledacrossthebreadthofanoceanbasin.HydrophoneshavepickedupbluewhalesoundsbroadcastoffIcelandandmonitoredthemastheycrossedtheAtlantictotheedgeoftheCaribbeanSea.Aretheycallingformates,checkingonfoodavailabilityorattemptingmorecomplexcommunication?AdeeprumblestartsintheiMonstercam’shydrophoneandquicklyoverloads

it.Theentireunderwaterhousingbeginstovibrate.Isitsomestrangewhaleorother large, noisy animal? The sound frequencies are not confined to the lowbassnotes;thesearesimplythesoundsthatareheardfirstandmostnoticeably.Infact, therearesoundfrequencies throughout thespectrum,fromlowtohighfrequencies.Thisis,inshort,noise.Butwhereisitcomingfrom?Ifitentersthesoundchannel,ofcourse,noisecanalsotravellongdistances,

so it could be far away. From time to time, the U.S. Navy conducts low-frequency sonar exercises that are capable of flooding large portions of oceanbasinswith loud,potentiallydamagingnoise,especially if thesoundsenter thedeep-watersoundchannels.TheNavyhasexcludedsome,butcertainlynotall,areas frequented by whales and dolphins, especially certain marine protectedareas,but these representonlyasmallportionof theactualwhaleanddolphinhabitatintheocean.Navy midfrequency noise from sonar exercises is thought to have caused

Cuvier’sbeakedwhales(Ziphiuscavirostris)andotherwhalestostrandanddieintheBahamas,theCanaryIslandsandGreece.From1957to1967,graywhalesabandoned a Mexican breeding lagoon in response to industrial activities,including noise, returning slowly over several years after the activities ended.Similarly, beginning in 1993, killer whales and harbor porpoises (Phocoenaphocoena)desertedanareaoftheBritishColumbiacoastwheretherewereloudacousticharassmentdevices,comingbacksixyearslaterwhenthedeviceswereremoved.Researcherswonderwhether the increase in numbers of bluewhales struck

and killed off the California coast over the past decade might be due to theincreasing levels of chronic ship noise,which is estimated to have doubled inintensity every decade since the 1950s. Such noise can mask the sounds ofwhales in searchofmatesor feeding spots.Thenoise effectively shrinks their

habitat,muffling their loud booming voices and rendering them invisible. Foranimalsthatusesoundasafood-gatheringandnavigationtool,losingtheabilitytosendandhearsoundscanhavedeadlyconsequences.Loudnoisesdonotbotheronlymarinemammals.Awidevarietyoffishand

even invertebrates, such as squid and crabs, have suffered injuries and beenkilledasaresultofloudnoises.Andthen,asouriMonstercamstartstodescendfarther,tothefrontierofthe

mesopelagic,aCuvier’sbeakedwhalerushespast,thesidesofitstorsoandheadsucked in from thepressure.Was it affectedby the loudnoises,orwas it justswimmingby?For the most part, the mesopelagic zone is off-limits to human divers,

althoughafewexperimentalscientificdiveshavedippedintotheupperpartsofthezone,usingparticularmixesofgastobreathe,decompressionchambersandother specially designed equipment. It is a highly dangerous undertaking, andmostmistakesprovefatal.At1,800feet(550m),nearlyhalfwaythroughthemesopelagiczone,Edward

Forbes’azoiczonestarts.Itsupportsanastonishingamountoflife,butsomuchmorewaterand life liebelow thissurprisinglyshallowmark.Wehavenotyetbegunourdescentintothetrulydeepwaters.

♦

Withthinbonesandareducedskeleton,thetransparentspookfish(Dolichopteryxrostrata),describedin2006,iswelladaptedtolifeinthedeep.Itisonlythreeinches(7.6cm)longanddwellsinthetwilightzoneofftheCapeVerdelslands,intheNorthAtlantic.Noteitsoddupward-lookingpouchlikeeyesandsmallmouth,whichisdesignedforcatchingtinyplanktonicprey.

AbreachingCuvier’sbeakedwhale(Ziphiuscavirostris)exhibitsthetypicalscarsfoundmainlyonmalebeakedwhalesthatarecausedbyothermales,eitherinplayorcompetition.TheCuvier’sbeakedwhaleissensitivetonoise,andanumberofmassstrandingshavebeenrecordedaroundtheworldfollowingNavysonarevents.Asaresult,theSpanishNavymaintainsa50-nautical-mile(92.6km)quietzonearoundtheCanaryIslands,wheremanybeakedwhalesarefoundandwheretheseincidentshaveoccurredinthepast.

Theopossumshrimp(Gnathophausiasp.)measuresaboutfiveinches(13cm)long,althoughonespeciesinthegenuscanreachalengthof14inches(35cm).Gnathophausiameans“lightjaw.”Aswithotherdeep-seacrustaceans,thedeeperthespecieslives,themorereducedisthecalcificationofitsexoskeleton.

B

DeepWaters

TheBathypelagic(Aphotic)Zone

3,300to13,000feet(1,000–4,000m)

ATHYPELAGICcomes from twoGreekwordsmeaning“deep” and“sea,”andthecompoundwordmeans“of,relatingtoor livinginthedepthsoftheocean.”Foroceanographers,itrefersstrictlytothatarea

oftheopenoceanfrom3,300to13,000feet(1,000–4,000m).As the iMonstercamdips into thisaphotic (no light)zone, thefishstillhave

eyes,mostlygiantorbs,eventhoughallsunlighthasdisappearedby3,300feet(1,000 m). In fact, in turbid waters or on poor-light days, sunlight turns tomidnightatamuchshallower level,but3,300feet (1,000m) isconsidered theabsolutelimitofsunlightpenetration.Belowthislevel,frombathypelagicwatersto the very bottom, this darkworld is completely devoid of light.There is nonightandnoday,andtherearenovisibledailycuesformovement.Ofcourse,therearestillflashes,theplayofbioluminescence,andthusanadvantagetobegainedbyfishor invertebrateswith largeeyes.Certainbig-eyedspeciesspendtheir days in this deep zone, perhaps partly to avoid predation, rising tomesopelagic and surface waters only at night to hunt. And many deep-seacreatures start their larval lives in surface waters, moving to their deep-waterhomesasadults.At 6,600 feet (2,000m), a third of theway through the bathypelagic zone,

however,theeyesofthefishweencounterbecomesmallerandsmaller,ontheirway to atrophy. By the time we are through this zone, the eyes are tiny,degenerateorabsententirely.Theshrimp,despitetheiroftenbrightorangetoredcoloring, are eyeless. This coloration is clearly not for other shrimp but mayservetocamouflagethecrustaceansfrompredatorswithbioluminescentpowersofilluminationthatusebluelight.hepressure intensifies in thiszone. It startsat1,470poundspersquare inch

(psi) at 3,300 feet (1,000 m) and finishes at around 5,880 psi at 13,000 feet

(4,000m).Manyofthedifferencesbetweenmiddle-layerandbathypelagicfisharethoughttobeduetothegreatlyincreasedpressure.Comparedwithmiddle-layer fish, those in the bathypelagic zone have a poorly developed centralnervous system, a weakly ossified skeleton and the absence or lack ofdevelopmentofaswimbladder.Otheradaptations,suchasalargerhead(attheexpenseofapunybody),comparativelylongerjawsandcurved-inteeth,havetodowith thepaucityofpreyat thisdepthand theneed tobe flexibleabout thesizeofthequarryandtomakesureitwon’tescapeoncecaught.It is not surprising to find creatures peculiarly adapted to life at this depth.

What ismostextraordinary is thatsomeanimals,suchas thespermwhaleandtheCuvier’sandotherbeakedwhales,routinelymovebetweenthiszoneandthesurface. Such adaptations have occurred because these air-breathingmammalsmustreturnregularly to thesurface.Theyare, ineffect, tethered to thesurfacebytheirneedtobreatheair,butinsomepartsoftheocean,theirfood,primarilyvarious species of squid, lives a mile or more below the surface. Whalesthereforeneedgoodvisionfor thesurfacewatersandalsorequireamethodofnavigating at night and in the dark without vision. For this, they use sound:active echolocation, sending out signals and reading echoes; and passiveecholocation, listeningfor thedifferences in thewaysounds reflectoffobjectsandtheunderwatertopography.Buthowdowhales,sharks,sealsandothermarineanimalsadapttochanging

pressure,fromafewpoundspersquareinchinsurfacewaterstomorethanoneton per square inch in the depths? Such a pressure change would implode ahuman’schestandsinuscavitiesinafewbone-crushingminutes.Inaddition,itwouldgiveadiver theultimatecaseof thebends,shouldheorsheever try toresurface.Whales, inparticular,have specialmechanisms toaccommodate rapid,deep

descentsandascents.Awhalemaystartwithsmallamountsofair.Below330feet(100m),theunderwaterpressurecollapsesitslungsandthorax,preventinggasfromenteringthebloodandreducingthecirculationofbloodtothemuscles.The rapid transmissionofnitrogen from theblood to the lungs as the creaturereturnstothesurfacemayalsohelppreventproblems.Sperm whales are well-known champion divers. Some of their deep dives

wererecordedinthelate1950swhenspermwhaleswerefoundsuffocated,theirlower jaws entangled in submarine telegraphic cables as they foraged. Morerecently,spermwhaleshavebeentaggedandstudiedtodeterminedivingdepths.These have reached more than 4,000 feet (1,200 m), with recorded sustainedunderwaterdivesexceedinganhour,althoughtypicaldiveslastfor45minutes,taking the whales to depths of 2,000 to 3,280 feet (610–1,000 m). Thus it

appearsthatspermwhaleshuntmainlywithinthemesopelagiczone;onlytheirrecord depths extend to the topmost part of the bathypelagic zone. Yetmuchdependsonwheretheirpreytravels.

Asexceptionalastheirbreath-holdinganddeep-divingexploitsare,whalesareusing“only”thetop27percentoftheocean,nowherenearthedeepesttrenches.Still,comparedwithhumandivers,whalesarecapableof

extraordinaryfeats.

Northernelephant sealswere the first tobeat the spermwhaledive records.Researchhasshownthattheseanimalscanspenduptotwohoursatadepthof7,835 feet (2,388m), although their typical dives are much less than that. In2014,CascadiaResearchCollective scientists reported new diving records formarine mammals off southern California after attaching satellite tags to eightCuvier’sbeakedwhales.TheseCuvier’sbeakedwhalesachievedrecorddepthsofupto9,816feet(2,992m).Thewhalesstayeddownforupto137.5minutes,alsoarecord.Ofcourse,divingabilityhasbeenmeasuredinonlyafewwhaleand marine mammal species. Whales no doubt swim deeper, but how muchdeeper?ThedeepestrecordeddivesforwhalesoffsouthernCaliforniapenetrateclose to the deepest part of the bathypelagic. As exceptional as their breath-holdinganddeep-divingexploitsare,whalesareusing“only”thetop27percentof the ocean, nowhere near the deepest trenches. Still, compared with humandivers,whalesarecapableofextraordinaryfeats.Themesopelagicandupperabyssopelagiczonesfeaturenotonlyalightshow

butalsoasoundtrackthatisfilledwiththeacousticalsignatures,communicationandnavigation soundsofvariouswhales: the loud, lowgroansofblueand finwhales; the incessant, intricate spermwhaleanddolphinclicks—someusedascommunication,someasecholocationfornavigation.Others,suchasthedeep-divingCuvier’s beakedwhale and theBlainville’s beakedwhale,which divesdeeper than the sperm whale but not as deep as the Cuvier’s, travel throughmuch of the surface and middle waters, quietly observing the flashing lightsgeneratedbyfishandvariousinvertebrates.Perhapstheyremainquiettoavoidattractingkillerwhaleandsharkpredators.Onlywhentheyarenearthedeepestpartoftheirdives,wherekillerwhalesandmostsharksareunlikelytobefound,

dotheybeginvocalizing.Maybethat’swhentheymostneedtheirvocalabilities—toseekoutandevendiscussthelocationoftheirfavoritesquidprey.Whales,dolphins,sealsandsealionshavethussolvedthechallengeofliving

andworkinginalow-tono-lightworldinprofoundlydifferentwaysthanhavefish, squid and jellyfish.The ultimate result of these different strategies is thecreation of an almost carnival-like atmosphere in themesopelagic and upper-bathypelagiczones,whicharealivewithlights,soundsandaction.Butthispartof the ocean ismuchmore than a sideshow spectacle. It’s akin to an outdoornatural history museum featuring some of the unrecognized wonders of theworld—a deep corner of the ocean that is alive with possibility, where thelanguageoflightandsoundisexpressedinadazzlingarrayofforms.Bioluminescent fish andbig-eyed squidcan seeandhear someof the lights

and sounds from other animals, butmuch, if not all, of itmust be confusing,devoidofmeaningexceptwithintheimmediatecontextofthatcreature’sworld.The “communication” may therefore often be pure deception, like themagician’sart.Whenwelearn thatoneanimalfollowsanother’s flashing lightonlytobecomeitsprey,webegintograspthemeaningbehindthelightshowsand to understand that the apparent disconnect between species—the crossedsignals—areinfactintentionalandpartoftheeverydayfrictionofpredator-preyrelationshipswithinanecosystem.There isnouniversal languagebetweenspecies in theocean, justas there is

no common language on land. It’s true that there are nutrient cycles, energyflowsandsomesymbiosesbetweenspecies,whereinspecies live togetherwithoneortheotherorbothbenefiting,withorwithouttheotherone“knowing.”Butif we accept that an ecosystem is a biological community of interactingorganismsandtheirphysicalenvironment,afunctioningecosystemcanlargelybeseenasadensetangleofrelationshipsamongspeciesthatinteractbutdonotreallycommunicatewithoneanother.Ourfamiliaritywith land-basedanimals,fromdogstoelephants,hasallowedustocracksomeofthecode.Buthumansstruggle mightily just trying to communicate within our own species—tounderstandthevisual,audioandothersignalsfromdisparatehumancultures,totolerateotherpeople,towagepeaceinsteadofwar.Asaresultofthisallocationofourtimeandenergy,ourunderstandingofthedeep-seaworldremainsspareandrudimentary.Midway through the bathypelagic zone, we meet one of the evolutionary

odditiesofthedeep:thevampiresquid.WhenWilliamBeebeencounteredthisspecies,hecalledita“terribleoctopus,blackasnightwithivorywhitejawsandbloodredeyes[and]sinisterarms.”Morebrownishredthanblack,butcertainlybig-eyed, the vampire squid is about eight inches (20 cm) long. It flashes its

photophores, thencovers themwith flapsofskin. It’sneitheranoctopusnorasquidnoravampire,however,butearneditsnamefromitsdarkcoloringandthewebbing found between its arms. Its blue eyes can turn deep red in a flash.Originallythoughttobeakindofoctopuswhenitwasdiscoveredin1903,thevampire squid actually has 10 arms, characteristic of a squid. But two of thearms are different from a squid’s tentacles—they are longer and lack suckers.These two special arms are tucked into little pouches outside theweb and areunfurled when needed, perhaps as feelers. Considered intermediate betweensquid and octopuses, the vampire squid has been placed in its own order,Vampyromorpha. Its species name, Vampyroteuthis infernalis, means the“vampiresquidfromhell.”While its name and appearance may seem monstrous, the elegant and

dexterous vampire squid swims slowly, waving its thin fins like wings andextending two longfilaments togatherdetritus,alsoknownas“marinesnow.”Far frombeingdangerous, thevampiresquidsubsistsonalgae,deadplankton,scraps from the shellsof the tiniest crustaceans andassorted fecalmatter.Thelargest recorded size for avampire squid is a female thatmeasured8½ inches(22cm)long.Notmuchofamonster.The vampire squid spends its entire life at depths of 3,000 to 10,000 feet

(900–3,000m).Duringmating,themaleplacesapacketofsperminthefemale’sgenitalopening,asdomostothersquidandoctopuseswhenmating.Whentheyhatch, the young have eight arms. The two feeler arms, the webbing and thelight-producingorgansdevelopwhenthevampiresquidislessthananinch(2.5cm)long.Ratherthanpretendingtobehighlydangerous,thevampiresquidwrapsitself

upinitsownarmsasiftomakeitselflooksmallerandlessconspicuouswhenapredator approaches. If that strategy doesn’t work, ink clouds may follow.Sometimes,thisanimalmayturntoself-mutilationtosaveitselffromapredator,breakingorbitingoffthetipofoneofitsarms.Thearmtip,glowingwithbluebioluminescence,thenfloatsaway,distractingthepredator,whichgetstonibbleon a snack but nothing more. Later, the squid regrows the arm tip. Self-mutilation,with numerous variations on the theme, is not a popular stunt but,rather,asurvivaltoolforvarioussquidspecies.As the iMonstercamhoversat6,600 feet (2,000m), itspowerful lightbeam

detects a massive dark shape looming in the distance. We drift closer toinvestigate. As we do, the smaller dark shapes of swimming figures—seals,sharks,morewhales?—loom intoview, likewise attracted to this sizableblackobelisk.Wehaveencounteredaseamount.Seamountsareunderwatervolcanoes,typicallyextinct,thatriseatleast3,300

feet (1,000m)fromtheoceanfloor.Theyarenotpartof themidoceanridges,the great underwater mountain ranges, but occur individually or in their ownsmallchains.Intheirgeologicallives,someseamountshaveproducedsomuchlava that they eventually manage to breach the surface of the ocean. At thatpoint, they are regarded as islands. The greatest seamount theworld has everseen is Hawaii’s Mauna Kea, which also became, technically, the highestmountainonEarth,rising18,000feet(5,500m)beforeitbrokethesurface,thencontinuingforanother12,000feet(3,650m),toppingoutat30,000feet(9,150m), about 1,000 feet (300 m) taller than Mount Everest. Most seamounts,however, remainhiddenbelow the surface of the ocean,where they tease andtorment submarines that fail to recognize the dense aggregation ofmarine lifeuntilitistoolate.A2011DeepSeaResearchstudyfromtheZoologicalSocietyofLondonand

University ofOxford researchers found that seamounts cover 5 percent of theoceanfloorandnumberapproximately33,000.Otherestimatesrangeashighas100,000. Most seamounts are understudied and underappreciated except byfishermen, who seek them out as some of themost highly productive fishinggroundsforcommercialspecies.Atthesametime,theirtrawlsandothernetsareresponsiblefordestroyingthem.Toalargeextent,oceanographersanddeep-seazoologistsofallstripeshavecometoseamountsonlyrecently,partlybecauseofthedifficulty andexpense required to reach them,apart from the few that risecloseto theocean’ssurfaceintoshallowerwater.Onlyroughly250seamountshavebeenstudiedfortheirbiologicaltreasures.Seamounts are magnets for life. Volcanic activity leads to an explosion of

living organisms that thrive in habitats of various depths, slopes, watertemperatures and currents, which create highly diverse ecosystemswithmanyendemic species. Studied in detail only since about 2000, deep-sea coralsflourisharoundandontheseamountsandhostsome1,300knownspecies,someofthemuniquetospecificcoralsandseamounts.Crustaceanssuchasstonecrabs(Parclamissp.),seasnailsandsquat lobstersandnumerousinvertebrates livingtogetheraddtothelushlife.Onatypicalseamount,athirdofthespeciesmaybeseamount-onlyresidents,andasmanyashalfofthesemaybespeciesunknowntoscience.TheWoodsHoleOceanographic Institution(WHOI) isoneof the leaders in

seamount research, undertaking submarine expeditions deep into the NorthAtlantictotheBalanus,NashvilleandRehobothseamounts,allpartoftheNewEngland Seamount Chain,whichwas formedwhen theNorthAmerican PlatemovedovertheNewEnglandhotspotmorethan100millionyearsago.Otherseamounts locatedfarthereast includeYakutatandCaloosahatchee,partof the

CornerRiseSeamounts.WHOImarinebiologistTimShankvisitedtheseareasin 2005 and found spectacular corals as well as sponges with two species ofcrinoids.Whennotpunctuatedbyamassiveseamount, thebathypelagiczoneextends

toadepthof13,000 feet (4,000m). In theopenseaoraboveoneof thedeepocean trenches, this depth marks only the halfway point, or less, from thesurface.Thisrangeencompasses theentiredepthof theseainmanyplacesoffthe continental shelf, which slopes down along numerous abyssal hills to theabyssalplains.Thebaseofthiszoneapproximatelycorrespondstotheaveragedepthoftheworldocean:12,430feet(3,790m).Still,theawesomepressuremounts,likeavisesurroundingandtighteningon

the iMonstercamfromevery side.Asmallbut fierce-lookinganglerfish swimsinto view. Instead of the barbel found on stomiatoid fish, certain deep-seaanglerfishhaveabonyprojectiononthetopoftheheadthattheyuseasaluretoattractprey.Thisprojectionwasoriginallypartofthefish’sdorsalfin.Throughevolution,thefirstspineofthefinmovedforwardandbecamemodifiedintoasortoffishingpole.Thesizeandshapeoftheprojectionvaryconsiderably.Mostinterestingistheadaptationofthegrooveinthefish’sheadtoholdthebonypolewhennot inuse, since suchaprojectioncouldbedistractingduringmatingoreatingandmightslowthefishdownwhenfleeingfromapredator.Thesolutionisready-made.Usingspeciallydevelopedmuscles, thefishadjusts thepositionofthepoleandlocksitinthegroove,closetothebody.SensingthepresenceofouriMonstercam,thisanglerfishbegins“fishing,”the

tipofitsfishingpoleflickeringandbeamingwithitsluminouslure—abeaconintheblackness.Asthecameracomescloser,theanglerfishmovesthelureneareritsmouth.Thenanawesomesight:Thebeastdropsitslowerjaw,thegillcoversexpand,andtheiMonstercamcomesface-to-facewithanenormousmawbefore... allgoesblack.Havewebeen swallowed?No—an instantbefore testing theteethofthisfish,theiMonstercamhasalertlydippeddownandoutofsight,backtothedarkness.Timetogoevendeeper.

♦

Aftersurfacingtotakemultiplebreaths,theBlainville’sbeakedwhale(Mesoplodondensirostris)returnstoitsdeep,high-pressureworldinsearchofsquidanddeepwaterfish.Here,offHawaii,itprefersdepthsof2,300to3,300feet(700–1,000m).

Everyday,thespermwhale(Physetermacrocephalus)undertakesnumerousverticalmigrationsbetweenthesurfaceandthedark,high-pressureworldoftheocean’sdeepwaters.Suchisthelifeofasquidhunterthatneedstoreturntothesurfaceatleastonceanhourtobreathe.

Previouspage:Thevampiresquid(Vampyroteuthisinfernalis)revealsitselfinitsnaturalhabitatinsequentialframestakenfromanunderwatervideosequencebytheMontereyBayAquariumResearchInstitute,inCalifornia.

(1)Thevampiresquiddriftsalonginatypicalfeedingposture,withoneofitstwolong,hair-linedfilamentsextended.

(2)Aclose-upview.

(3)Therearview,withafeedingfilamentextended.

(4)Thesquidusesitsarmstoscrapefoodoffoneofthefilaments.

(5)Thevampiresquidopensitsweb,revealingsome“marinesnow”fooditems, visible aswhite specks in itsmouth and in the surroundingwater.Thesoft,fingerlikeprojectionsonthesquid’sarms,knownascirri,maybeused to transfer food to themouth.What is“marinesnow”food?A2012study revealed that squidmainly eat particles of deadplankton, scraps ofthe shellsof the tiniest crustaceans, algae, assorted fecalmatter andotherdetritus. Despite its frightening name, a vampire squid is about asdangeroustohumansasapetgoldfish.

(6)Thevampiresquidmovesslowlythroughthedeep,darkwaters.

(Allphotographs©MBARI)

Cold-watercoralsuchasSolenosmiliasp.andbamboocoral(seenherewithapolychaete,orbristleworm)havebeenrecoveredfromthecoralseamountneartheDragonVentFieldontheSouthwestIndianRidge.Trawlingandoceanacidificationcausedbyrisingcarbondioxidelevelsareagrowingthreattodeep-seacoralenvironments,whichshelterjuvenilefishandare,therefore,vitaltotherecoveryofcommercialfishpopulations.

Thisdeepwaterspiralingcoralwasfoundat6,500feet(2,000m),livingalongtheedgeofasteepwallcliffsouthoftheDeSotoCanyon,intheGulfofMexico.Notetheslender-leggedchirostylidcrab(Eumunidapicta)makingitshomeamongthedelicatebranchesofthecoralcolony.

Mostofthe14,000copepodspeciesare1⁄25to1⁄8inch(1–3mm)long,butthisdeep-seacopepod(Gaussiaprinceps)isagiant,measuringmorethananinch(2.5cm)acrossitsantennae.Itsometimesescapesitspredatorswithabioluminescent“fireworks”display,whichleavesadistractingbrightcloudtrail

behind.

B

DeeperWaters

TheAbyssopelagicZone

13,000to20,000feet(4,000–6,000m)

LACK is black, and there is no perceptible light change as theiMonstercam sinks ever deeper. The pressure gauge, however,continuestoriserapidly,from5,880to8,820poundspersquareinch,

as the iMonstercamventures through the abyssopelagic zone.Our lights seemmore intrusive at this black depth, andwe occasionally switch them off for atruerpicture:nothingbutblackness.Translated literally from the Greek, abyssopelagic means “bottomless sea.”

AbyssisoneofthemoreevocativewordsintheEnglishlanguagetodescribeanunfathomablechasm,ayawninggulf,animmeasurablyprofounddepthorvoid.At2½toalmost4miles(4–6km),theabyssisextraordinarilydeep,thoughitisstillnotthedeepestpartofthesea.Theabyssspansavastareaoftheoceanbottom—themajorityoftheabyssal

hills (the single most common geological feature on Earth) and the abyssalplains.Together, theycomprisemuchof theoceanbottom—allbut the ridges,whicharetheextensivevolcanicareasborderingalltheplates,andthetrenches,which dip well below the abyssal plains in the western Atlantic and Pacificoceanstodepthsbelow20,000feet(6,000m).Here,webeginthezoneofthetinyandno-eyedmonsters.Despitethesteadily

diminishing size of many fish and invertebrates, however, some invertebratesshow the opposite trend and become larger. The deep-water giant red mysidGnathophausiaingensreachesalengthofnearly14inches(35cm),fifteentimesthesizeofmysidsintheupperwaters.TheisopodBathynomusgiganteusgrowsto 16½ inches (42 cm), comparatively gargantuan proportions, while theamphipod Alicella gigantea can be 7½ inches (19 cm) long. The copepodGaussia princeps achieves a size of slightly less than half an inch (1 cm),nearly10timesthesizeoftheaveragefree-swimmingcalanoidcopepodnearthe

surface.Brightredshrimpcanbe12inches(30cm)long,withantennaetwicethatlength.Someseaurchinsontheseaflooratthisdepthare12inches(30cm)indiameter,upto10timesthediameterofshallow-waterspecies.

Gigantismmayariseforseveralreasons.First,scarcefoodandlowtemperaturesreducethegrowthrateandincreaseboththetimerequiredforsexualmaturityandlongevity,leadingtolargersize.Second,gigantismmaysimplyrepresentapeculiarityofmetabolismathigh

pressure.

The ultimate textbook example of gigantism, however, is Architeuthis dux,the giant squid. The scientific name says it all. TheGreekword arkhimeans“chief”or“mostimportant”andteuthismeans“squid,”andtheLatinduxmeans“leader”;thus“chiefsquidleader.”Whilesomesquidspeciesaremerelyaninch(2.5cm)long,thegiantsquidhastakengigantismtoanawesomeevolutionaryend.Thelongestoftherelativelyfewgiantsquidthathavewashedashorewasa57-foot(17.4m)femalefromNewZealandwaters,althoughresearcherscautionthat themeasured length canvarydependingon the elasticity of the tentacles.Thought tobe the largestofall invertebrates in length, thismolluskcanweighuptoaboutaton(900kg).Itseightshorterarmshavehundredsofsuckers,andits two nearly 40-foot-long (12 m) tentacles each boast at least a hundredserratedsuckersattheend.Gigantism may arise for several reasons. First, scarce food and low

temperatures reduce the growth rate and increase both the time required forsexual maturity and longevity, leading to larger size. Second, gigantism maysimply represent a peculiarity of metabolism at high pressure. In any case,natural selection almost certainly plays a role. Large size, delayed sexualmaturity and a longer life would all be useful to a deep-sea creature. Largeryoungcouldavoidpredators,feedonawiderrangeoffoodsizesandsearchoverabroaderareaforfoodandmates,andgreaterlongevitywouldgivetheanimalsmoretimetofindmates.However, some squid achieve large sizes rapidly and die relatively young.

The giant squid’s presumed maximum longevity of no more than five years

exceeds some other squid species but seems brief relative to a whale’s 50-to200-yearlifespan.Awhalemightproduceonlyonecalfeverytwotofiveyearsover a few decades, depending on the species. During its short life, the giantsquidmay be extraordinarily fruitful, producing thousands of offspring, as doothersquid.Gigantismaffectsonlycertainspeciesatthisdepth.Mostinvertebratesinthe

deeparesmallerthantheirshallow-seacounterparts.Infact,theoveralltrendinthedeeperpartsoftheseaandonthebottomistowardminiaturizationandoftenextrememiniaturization.Inrecentyears,oceanographershavebeguncollectingspecimens using 0.3-millimeter screens, noting that few species appear in 1-millimeter screens,which aremuch finer than the dredges of old.Despite thetalesofseamonsters,thedeepseaismainlya“smallorganism”habitat.It is eerily quiet down here. The noise that rattled the iMonstercam’s

hydrophone in the deep-water sound channels and the distant cries of whalesnowappearfaint.In termsofpressure,wearemoving into the landof collapsedvehicles and

shrunkenheads.Thepressures that seem to forcemanycreatures tostaysmallareevident in the“experiments”conductedbydeep-seaoceanographers.SomeoceanographerswhospendalotoftimeatseadroppingresearchpackagesoverthesidesofshipsattachapieceofStyrofoamandsenditdowntoseehowsmallit iswhen thepackage ishauledback to thesurface.Ofcourse, thedeeper thepackageisdropped,thesmallertheStyrofoamwhenitreturns.Styrofoamcupsturnintotwistedthimbles.The joke became a lesson in physics, as seasoned oceanographers began to

initiate their graduate students in the ritual of measuring, attaching and thendroppingtheStyrofoam.Theresultssoonattainedthestatusofprizedsouvenirs,coveted by young researchers eager to show how deep their expedition hadplumbed.SomeoceanographersbringalongaStyrofoamheador two, the sortused to display hairpieces and hats, demonstrating what the deep does tosomething the size of a human head. The result—equivalent to the shrunkenheadsthatNewGuineanativesoncecollected—oftenproducesnervouslaughterasthetinyheadispulledupfromthedeep.

♦

Living1½miles(2.4km)deepintheCelebesSea,thispink,transparent,unnamedseacucumberhasjusthadameal—noteitsfullgut.Afteringestingandfilteringmatterontheseabottomforfood,thisseacucumberusesthewinglikecollararoundthefrontofitsbodytopushoffthebottom.Itthenridesthecurrenttoafreshfeedingspot.

thecurrenttoafreshfeedingspot.

A

DeepestWaters

TheHadalZone

20,000to36,200feet(6,000–11,000m)

BYSSwouldseemtobetheultimatedepth,butbeyondtheabyss isthehadalzone.Hadesistheunderworld—hell—andsothehadalzoneisthedeepestregionoftheocean.InFrench,thewordisHadès,butit

allgoesbackagaintotheGreek.InHomer’swork,Hadeswasthenameofthegodof thenetherworld,but in later times, itbecame thenameofhishouseorkingdom,hisnetherworldabode,theabodeofthedeaddepartedspirits.The hadal zone in the sea comprises the trenches all around the Pacific,

especiallyinthewesternPacific,aswellastheeastern,centralandSouthPacificoff the coast of Central and South America. There are also trenches in thenortheast Indian Ocean off Indonesia, the northeast Caribbean and the SouthAtlanticnearAntarctica.Ifmostoftheseabedofthedeepoceanconsistsoftheabyssalhillsandplains, thehadalzoneis theareawheretheplainsdropoff injagged rocky crevasses that plunge up to three miles (5 km) deeper than theabyss,tothebottomoftheworld,tothemuddypitsclosesttotheEarth’score.These wide trenches mark where the ocean’s spreading seafloor plates havecollidedwithland-bearingplates.Themovementofthetectonicplatesinthesepotent earthquake zones produced the trenches, just as it created the longmountainriftvalleyofthegreatmidoceanridge.As the iMonstercamdescends into the seeminglybottomless trench, the fish

becomeeversmaller.Someremainblack,butothershavebecomedirtywhiteoreven colorless, lacking all pigment. In this zombielike land, there seem to befeweranimals,buttheexpectationofwhatfurtherstrangeformsmightbeseenlurkinghasgrownconsiderably.Andourcuriosityaboutwhatmightcrawlonorintheoozeatthebottomoftheseaiswhatkeepsourinterestticking.Willthebottomprovetohavemorelifethanthesedeep-waterlayers?Itisevenquieterdownhereinthetrenches.Loomingoutoftheblack,might

weseethesecretsubmarinesoftheworld’spowerfulnavies(theyaresaidtousethe trenches in the Pacific)?Navy submarines strive to be quiet and to listen;they would hear us before we ever hear them. A few submarines could becrawlingaroundus,andwewouldneverknow.Thepersistenceoftheblacknessatthislevel(howmuchblackercanitget?)is

nodifferentfromthatoftheabyssopelagicorbathypelagicwaters.Buttheevergreater distance from the photic zones, from the source of the sun, and thedramatically increasingpressuremake thisas forbiddingaplace forhumans—andanimalsingeneral—asanywhereonEarth.Untilnow,thepressurehasintensifiedthrougheverydescendingzone,butthe

differencebetweenthetopandthebottomofeachzoneismuchlessthanitisinthehadalzone,whichoccupiesuptohalfthedepthofthesea.Asweenterthehadalzone, thepressure is600atmospheres (600 timeswhatweexperienceatthe surface),which translates to8,820poundsper square inch (psi).But that’sjust the starting point.Whenwe reach bottom—up to 36,200 feet (11,033m)deep in the Pacific trenches—the pressure will exceed 1,100 atmospheres, or16,170 psi. That’s more than eight tons pressing on every square inch of theiMonstercam.Some would say the hadal zone is aptly named, maybe even an

understatement,forthisblack,frigid,high-pressurehellhole.Butthisperceptionistrueonlyforthosewhocannotstandthepressure,thecold,thedarkness,thecomparative lackof food.According to someevolutionarybiologists, thedeepsea represents the margins, where species that couldn’t survive in the upperlayerswereforcedtogo.Yettothoseanimalsadaptedtolivinghere,it’shome.For all the extremes, the hadal zone offers constancy.Any species that can

moreorlesscountonthesameenvironmentalconditions—dayandnight,seasontoseason,yearbyyear—hastremendousadvantages.Deepseaspeciesareneverbotheredbyhurricanes,iceagesortheeffectsofElNiño.Thingsmoveeversoslowly in the deep sea, but the trenches miss most of that too. The naturalhazardsofdeep-sealife,suchasoccasionalunderwaterearthquakesandvolcaniceruptions,however,canbecataclysmicwhentheyhappen.Historically,thequesttofindoutwhetheranythinglivedatthebottomofthe

seafollowedtwomainthreads.Thefirstpartwassimplytodropdredgesandtryto haul up bottom fauna from ever deeper portions of the bathypelagic,abyssopelagicandhadalzones.Thesecondwasafarmorechallengingmission—for humans to visit the depths and see what the ocean bottom was likefirsthand, following in the bubbles of William Beebe, who championed themidwatersinhisbathysphere.

ButwasThomsonmerelyluckyinhischoiceofsites,orwastheentiredeepseasimilarlyfulloflife?Wouldthatlifecomprisethesamekindsofspecies,orwoulditbecompletelydifferent?Andwherewereallthoseliving

fossils?

EdwardForbesstartedtheinitialpushtodredgelifefromthebottom,buthegaveupearly,declaringanazoic,orno-life,zonebelowadepthof1,800 feet(550m).Takingupthequestinthe1850s(andlaternamedtoForbes’chairofnaturalhistoryattheUniversityofEdinburgh),CharlesWyvilleThomson(laterSir Charles) became convinced that there was life on the bottom and, afterreadingDarwin, thatsomeof this lifemightevenbeancient.Heandothersofhistimewonderedwhetherthedeepseamightbearefugeforextinctforms,theso-calledlivingfossils.Thomson traveled toseeNorwegianbiologistMichaelSarsandhisamazing

collectionofmarineanimalsdredgedfromthe1,800-foot-deep(550m)LofotenFjord. Most notable was a primitive kind of echinoderm—the phylum, ortaxonomic category, that contains starfish, brittle stars, sea urchins and seacucumbers—acrinoid,orsealily(classCrinoidea),thenknownonlyfrom120-million-year-old fossils from the early Cretaceous period. The stalked sea lily(Rhizocrinuslofotensis),sometimesuptothreefeet(1m)tall,lookedmorelikeaplantthanastarfish,butitwasactuallyananimalthatkeptitselfanchoredtotheoozeandobtainedfoodbysweepingits“fronds”throughthewater.Thesealily,andthepromiseofadditionaldiscoveries,enabledThomsonand

hisfriendW.B.CarpentertoenlistthesupportoftheRoyalNavy.ThroughTheRoyalSocietyofLondon, theyexplored thedeepwatersnorthandwestof theBritish Isles and extended south to the Iberian Peninsula. Annual summerexpeditions began in 1868 aboard theHMSLightning, followed in successiveyearsbytheHMSPorcupineandtheHMSShearwater.Penetratingthebottomoozeatdepthsextendingdownto14,610feet(4,450m)—nearly2¾miles(4.5km)—thecrewpulledupdredgeafterdredgecontainingevidenceoflife.Forthemost part, they found skeletons of animals that had fallen from the surfacewaters, but in July 1869, at the edge of what would come to be called thePorcupineAbyssalPlain,southwestofIreland—thegreatestdepththeyreached—the ship’s creaking 12-horsepower engine helped haul up the deepest prize:

various species of mollusks, annelid worms, sponges and echinoderms, trueinhabitantsofthedeep.Thomson had rendered lifeless the idea of Forbes’ azoic zone. But was

Thomsonmerelyluckyinhischoiceofsites,orwastheentiredeepseasimilarlyfulloflife?Wouldthatlifecomprisethesamekindsofspecies,orwoulditbecompletelydifferent?Andwherewereallthoselivingfossils?Keen to answer these and other questions, Thomson plotted a

multidisciplinary round-the-world cruise.Besides all the life he had found, hehad taken temperature readings at various depths that stirred arguments aboutocean circulation and the possible role of the deep sea. Returning to enlistsupport,ThomsonfoundtheRoyalNavyeagertosurveythedeepbeforelayingsubmarine telegraphcables.With theRoyalNavyandbroadscientificsupport,Thomson was able to organize what became a 3½-year cruise on the HMSChallenger. From 1872 to 1876, the ship logged 68,930 miles (110,930 km),performed some300dredgings and trawls, and pulled up an estimated 13,000plantandanimalspeciesfromthedeep,includingnearly5,000newspecies.Intheearlydays,themenonboardtheshipgatheredroundtoseewhatwas

hauledup,wonderingwhatnewmonstersmightappear.Butsoonthetediumoftheendlessstations,wherethedredgewouldbesetdown,onlytotakehourstohaulup,was closer to leading tomutiny thananythingelse.Ever the engagednaturalist, Thomson sustained his curiosity throughout. Occasionally, bizarrebioluminescent treasures were snared by the dredges, yet no bona fide seamonster or dinosaurlike living fossil appeared, with one possible exception: asmall Spirula squid, considered a missing link between ancient and modernsquid.Thomson found little to support the great 19th-century idea of fossil sea

monsters. Other researchers would later find a few “living deep-sea fossils,”such as the turn-of-the-century vampire squid described earlier and thecoelacanthdiscoveredoffSouthAfricain1938andthoughttohavebeenextinctfor70millionyears.Thesewereenoughtokeeptheideaalive,barely.Fossils,living or dead, were just not as prevalent in the sea as had been hoped orbelieved.Infact,thediversityofthedeepseawassomewhatofadisappointmenttoThomsonandotherswhotookpartintheChallengerExpedition,despitethelarge number of specimens they collected. Only later would they realize thattheirmethodofdredgingwaslargelytoblame.Whenthemeshesbecamefinerin the 1960s and the techniques for capturing life at depth more refined,scientistswereabletopullupmanymorespecies.A turningpoint in oceanography, theChallengerExpedition took soundings

throughouttheocean,makingpossiblethefirstglimpseoftheshapeanddepths

oftheworldoceanbasin.ItdiscoveredthemidoceanridgeintheNorthAtlantic,partoftheworld’slongestmountainrange,andhelpeddefinethelocationoftheworldocean’smajortrenches,thedeepestplacesonEarth.ItactuallyfoundthefamousChallengerDeep—thedeeppart of theMarianaTrench, nearGuam—andpulled up a bit ofmud just 50miles (80km) from the very deepest spot.ThomsonspentagoodpartoftherestofhislifeexaminingthefindingsoftheChallengerExpedition,writingupandediting34largevolumesonthebiologyalone,aswellaselaboratingonmanyoftheotherdiscoveries.The Challenger Expedition paved the way for American and European

oceanographicexpeditions.At theadventof the20thcentury,PrinceAlbertofMonaco trawled at 20,000 feet (6,000m) on the abyssal plains and pulled upbrittlestars,afishandseveralothersmallorganisms;formanyyears,heheldtherecordforcreaturesfoundatdepth.Not until the Danish Deep Sea Expedition aboard the Galathea (1950–52)

were the trenches finally studied. The depths of the Philippine Trench weresampledwith a dredge that descended 33,400 feet (10,180m).While not theverybottomofthesea,itwaswithin1,400feet(430m)ofitandwasdeepintothe hadal zone. The term “hadal” was, in fact, coined in the wake of thisexpeditionbyoceanographerandzoologistAntonF.BruunofCopenhagen.Galathea’sdredgebroughtupseaanemones,mollusks,bristle,orpolychaete,

worms and plenty of sea cucumbers—essentially mud-eaters, creatures thatingest mud for the food it contains. These same groups of animals had beenfound80yearsearlierbytheChallengerExpedition,althoughthespeciesturnedouttobedifferent.Trenchspeciesweremainlyechinoderms,onthesmallside,notmonstersandnotfish.Althoughdredgesareunreliableforpickingupfishatdepth,itwouldappearthatthenumber(biomass)andspecies(diversity)offishdeclineinthetrenches.The Galathea had gone deep with its dredge but had not reached the very

deepestpartofthetrenches.In1951,thesameyeartheGalatheadiditsdeepestwork,theHMSChallengerII—aBritishshipcarryingthenameofitslegendarypredecessor—usedsoundwavestomeasurethebottomintheMarianaTrenchinaportionofthePhilippineTrenchsouthwestofGuam.CalledChallengerDeep,the depthwas recorded at 35,760 feet (10,900m). The honor of reaching thedeepestrealmonEarth,ofactuallycomingintocontactwithit,wouldbesavedforamanneddescent.AboutthetimethatWilliamBeebewaspreparingtodescendtothedepthsof

the midwaters, Swiss physicist and inventor Auguste Piccard was breakingrecords with his high-altitude balloon attached to an aluminum gondola,climbing to a chilly height of more than 10 miles (16 km) while breathing

pressurizedoxygen froma tank.ButPiccardwasalsocontemplating thedeep.Freshfromhistriumphsintheupperatmosphere,PiccardmetBeebeatthe1933ChicagoWorld’sFair and saw thebathyspheredesignedbyOtisBarton.Overthe next quarter-century, Piccard worked on designing and building a smallmannedvehicle to explore thedepths—something trulyworthyof JulesVerneandhisTwentyThousandLeaguesUndertheSea.Piccardlikedtheideaofthesturdy, pressure-resistant steel sphere with which Beebe and Barton had hadsuccess.Piccarddesignedhissubmersiblealittlelarger,atsevenfeet(2m),andmuchstrongertowithstandgreaterdepths,completewiththickersteelwallsandportholes of a then experimental plastic called Plexiglas. His major advance,however,waseliminatingthetethertotheship.Piccard’sinventionwouldbearealunderwatervehicle.Adaptinghisideasaboutballoonstodeep-seavehicles,he designed a craftwithmultiple chambers in large tanks that could be filledwithair, seawaterorgasoline,whichwas lighter than seawater.Healsohadacompartmentforironballast,inpelletform,thatcouldbedropped,asneeded,toriseorreturntothesurface.Piccardcalledhisinventionthebathyscaphe.Itwasnotjusta“deepsphere,”

in the literalGreek translation ofBeebe andBarton’s bathysphere, but a deepboat.Onceitwasatthedesireddepthlevel,thebathyscaphereliedonpropellersforforwardmovement.Thevehicle turnedout tobeslow-movinganddifficultto maneuver, and innumerable test runs only minimally improved theperformance.The first bathyscaphe prototype, funded by the Belgian government, was

testedin1948.Itcarriednopassengersandmetwithmixedsuccess.Thereafter,sponsorshipforimprovedmodelswastakenoverbyvariousSwisspatronsandbythecityofTrieste,Italy.In1953,thenewlynamedTrieste,twiceaslongastheoriginalbathyscaphe,waslaunchedoffNaples.Piccard,nownearly70yearsold,wasjoinedbyhis31-year-oldsonJacques,andthepairdescendedtwomiles(3 km), bumping down into sediment and slowly sinking. Going nearly fourtimesasdeepasBeebeandBartonhadtwodecadesearlier,thePiccardsbrokeall records,but theircelebratorymoodwasmutedwhen theycouldseeno lifeoutsidethecraft.PartoftheproblemwasthattheTriestewasmiredinthemud.Evenwith the ship’s powerful outside lights, they could see nothingmoving.Hadtheyfrightenedeverythingaway?To some extent, perhaps they had, but theMediterranean is also somewhat

less densely populated by deep-sea life, as other pioneer researchers back toForbesandevenAristotlehaddiscovered.Inanycase,thePiccardshadtofindnewsponsors.In1957,theU.S.Navycommissioned15dives(laterincreasedto26) in the Mediterranean off Naples. Jacques Piccard worked as the pilot,

escortingnavalscientistsonebyonetomakeobservationsanddoexperiments.Althoughtheprimaryworkwascommunications-andweapons-orientedforColdWardefense, theydid findplentyofbioluminescent fish in themidwatersandconsiderablelifeinthedepths.Pleasedwith thework, theU.S.Navy purchased Trieste from the Piccards,

alongwith the servicesof JacquesPiccard.Partof thedealwas that theNavywouldbuildanewTrieste,with thickersteelwalls, smaller, strongerportholesandotherinnovationsthatwouldallowittodescendtoevendeeperseas,toscalethedeep-oceantrenchesandvisittheverybottomoftheworldocean.Piccard,whohadkeptalivehisandhis father’sdream togo to theabsolute

bottomofthesea,finallyhadhisbigchance,andthedeeppocketsoftheColdWar U.S. Navy would pay for it. His father Auguste, who had spent yearsdesigningtheoriginalcraftandaccompanyinghissonondives,wastheninhislate70s,buthefollowedhisson’sexploitsfromtheothersideoftheworld,inSwitzerland.After a few test runs off San Diego in 1959, the craft and personnel were

transported across the Pacific to Guam, the U.S. base nearest to ChallengerDeep,intheMarianaTrench,thedeepesttrenchintheocean.On theovercast earlymorningof January23,1960,Piccardwasaboard the

USSWandank,ridingthehighswellsoftheopenPacificsome250miles(400km) southwest of Guam, more than 1,000 miles (1,600 km) east of thePhilippines. Piccard stood watching and listening as a nearby survey shipdropped hundreds of TNT charges to try to pinpoint the deepest spot inChallengerDeep.Hewonderedwhether itwasgoing tobe too rough toboardtheTrieste.Minutes later,however,PiccardandNavyLieutenantDonWalsh scrambled

aboard, sealing the hatch behind them. The excitement of the launch diedquicklyasthebathyscaphedroppedfromthebluewaterstotheblack—andthentoblackandmoreblack.Movingatanaveragespeedofjust1½milesperhour(2.4 km/h) through an ever-tightening vise of the most intense pressure everexperienced by a human craft, the Trieste took nearly five hours to reach thebottom.At 32,400 feet (9,875 m), Piccard and Walsh heard a strong, muffled

explosionandthoughttheymighthavehitbottomor,worse,thesteepwallsofthe trench.TheTriesteshuddered,andPiccard, ifnotWalsh,wonderedbrieflywhether a terrible implosion was imminent. But nothing happened, and theycontinuedtheirdescent.Finally,the150-ton(136,000kg)Triestetoucheddownon the bottom, and like two astronauts landing on anotherworld, Piccard andWalsh gazed out through the portholes. On the other side of the glass, their

spotlight lit up the netherworld. It was another world. “The bottom appearedlightandclear,”wrotePiccard,“awasteofsnuff-coloredooze.”So thiswaswhat it looked like at 35,814 feet (10,916m)—6.8miles (10.9

km)—below the surface, with 16,000 pounds (7,260 kg) of pressure beingexertedoneverysquareinchoftheTrieste.Theyhadjustgonewherenohumanhad gone before, but what Piccard and Walsh actually glimpsed from theportholes was somewhat anticlimactic. There was no King Neptune to greetthem.AndunliketheastronautsonthemannedMoonlandingthatwouldhappenat the end of the same decade, they could not step out of their craft onto thesurface of this new world, plant a flag and say something memorable. Therewere no hellish monsters at the hadal depths. In fact, the signs of life wereminimal,thoughnotable.Piccard thought he saw a flatfish, about a foot (30 cm) long, lying on the

bottom.Mostsurprising,ithadeyes.Blindedbyaspotlightthousandsoftimesbrighterthananythingithadeverexperiencedinitsrecentevolutionaryhistory,muchless its life, theflatfishslowlyswamoff into theblack,never tobeseenagain,certainlynotbyhumansandprobablynotbyanyothercreature,duetotherarityofeyesandtheabsenceoflightorevenbioluminescenceatthisabsolutedepth.Piccardalsospottedalargeredshrimp.Yetnophotographsweretaken.Inwhatmust surely ranknear the topof theall-timemissedopportunities, thepaircarriednocameraonboard.PiccardandWalshshookhandstomarktheiramazingfeat,thenmanagedto

makeexcitedvoicecontactwiththesurface,relayingtheirdepthandestimatedtimeofarrival.Withthetemperaturemeasuringonly50degreesF(10°C)insideand36.5degreesF(2.5°C)inthewater,theybothfeltchilled.Twentyminutesafter reaching the bottom, they began their ascent. After another 3½ hours,hungry for fresh air and eager to get out of their underwater “elevator,” theybroke the rough surface and struggled to emerge from their cramped quarters.Two Navy jets tipped their wings overhead in salute, and two photographerssnappedphotos.Tothebottomoftheworldandback,allinaday’swork.Ithadtaken decades of planning and dreaming.Nearly seven years earlier, in 1953,mountaineershadclimbedtothetopofMountEverest;in1957,astronautshadmanagedtoorbittheEarth.Now,finally,humanshadreachedthebottomofthesea.Itwasuntrue that thebathyscaphehad startedbending inon itself, as some

reportsclaimed,butasexpected, itdid shrinkbya few inchesunderpressure,producingaflurryofpaintflecksfromtimetotimeindeeperwaters.Muchmoreworrisome,however,was the fact that theplasticwindowon theantechamber,which was the escape route, had cracked in various places because of the

differentratesofcontractionoftheplasticandthesurroundingmetal.Itwasnotcaving in, but itwas a concern and had caused themuffled explosionPiccardand Walsh had heard on their descent. After the deep dive, Navy engineersdecidedthattheTriestewasunsafeandwouldbeunabletowithstandpressuresof 16,000 pounds per square inch again. By 1963, the record-breaking littlevesselwasretired.Had the Trieste caved in, it would have produced an awesome implosion,

propelling and scattering material for a great distance in all directions. Therewouldhavebeennorescueattemptorevenacleanup.Noothervehicle,mannedorunmanned,couldreachanywherenearthatdepth.Since 1960, the U.S. Navy has not built any new submersibles capable of

scalingthehadalcanyonstothebottom.NoneoftheColdWarnuclear-poweredsubmarines can travel in the deep trenches, though absolute-depth capabilityremainsclassifiedinformation.Kaikō,aJapaneseunmannedremotelyoperatedvehicle(ROV),hadhadal-depthcapability,andinMarch1995,itventuredtothebottomofChallengerDeeptoadepthof35,797feet(10,911m),just17feet(5m)shyof theTrieste’s record,althoughstillwithin themarginoferror.Kaikōmade two subsequent journeys to ChallengerDeep, collectingmanymicrobesand other specimens, before itwas lost at sea in a typhoon in 2003. In 2009,Nereus,aWoodsHoleOceanographicInstitutionROV,alsoreachedclosetothedeepestrecordeddepthbutwithouthumanoccupants.Itwouldbelefttoprivateenterprise,sotospeak,tohelpinspire,fundandtry

to match Piccard and Walsh’s journey to Challenger Deep. This first soloattempt to reach thebottomof the seawouldusher in anewcenturyofdeep-ocean exploration. Space travel was being taken over by private companiesdrivenbythevisionofafewindividualssuchasRichardBranson,anddeep-seaexplorationlookedtobedevelopingalongsimilarlines—withatwist.Thedeepsea was about to be invaded by a Canadian-born filmmaker with deepHollywoodconnections.The route that James Cameron took to the bottom of the sea was far from

direct—or straight down. Cameron flirted with physics classes as a student.Later, as an adult, he liked to experiment with special-effects technologiesrelated tounderwater filming.Morebroadly,heexplored science fiction scriptideas in such films as The Terminator, Aliens and The Abyss. He madedocumentaries on the deep. He earned an enormous amount of money, someyearsasthetopearnerinHollywood,enoughthathecouldtakehistimetoshootseveral of the biggest-budget films thewayhewanted and even to finance anexcursion to the deep.As a director and producer, he could be a tyrant and aperfectionist,andafewcolleaguescalledhimtheCaptainBlighoffilmmaking.

Noneofthesetraitswasperhapsideal,giventhelevelofcooperationneededtoundertake a successful journey to theMariana Trench, although perfectionismand attention to detail in outfitting and testing the sub would help ensure itsoccupant’ssurvival.When James Cameron accepted Best Director and Best Picture Oscars for

Titanic, the 1997 romantic disaster epic that became the first film to earn abilliondollars, he famouslyproclaimed, “I’m thekingof theworld!” Itwas agrand boast, a reprisal of a line from the movie spoken by the LeonardoDiCapriocharacterJackinamomentofromanticlargesse.Thekingoftheworldwasnowaimingtobekingofthesea.Amodern-dayWilliamBeebe,Camerondecidedearlyonthathisjourneyto

theMariana Trench would be a film documentary, and he engaged the idealpartner in the National Geographic Society. The Society had the televisionplatform, the lustrous history of exploration, the PRmuscle and the technicalreinforcement thatCameron required for such a complex expedition.Cameronstartedonhismission in2005.At the time,hewasworkingonotherprojects,includingthelong-awaitedrealizationofhissci-fivisionAvatar.AfterAvatar’sworldwidereleasein2009,Cameronturnedhisfullenergiesto

finishinghispreparationsforthetestingofDeepseaChallenger,theone-personsubmarinethathehadcodesigned,thevehiclethatwouldtakehimtothebottom.It was not a government-issue sub backed by some powerful navy, but asCameron put it in his 2013NationalGeographic article, itwas a “little greentorpedo … built privately, in a commercial space sandwiched between aplumbing-supply wholesaler and a plywood shop in the suburbs of Sydney,Australia.” In addition to the sub, Cameron had helped design tiny high-definition3-Dcameras in titaniumhousings to takeclose-upsofwhathe saw.Healsobroughtalongtworefrigerator-sizedunmannedvehiclestodivewiththesubandsamplethesediment,seawaterandspeciesnearthebottom.Thenameofthesub,DeepseaChallenger,camefromtheoriginalChallenger

ExpeditionbywayofChallengerDeep,thedeepestpartoftheMarianaTrench,which was Cameron’s goal. Cameron was, indeed, challenging the deep sea.Weighinginat12tons(10,900kg),the24-foot-long(7.3m)lime-greensubhadyettobetestedunderoceanconditions.Cameronhadmademorethan80deepsubmarinedives,33ofthemtotheRMSTitanic,butthisnewvehiclewasgoingto a depth far beyond any he had ever attempted.He needed to knowhow topilotitandwhattodoifthingswenthorriblywrong.Twelvesmall thrusterswouldmovethesubonce it reachedthebottom—six

each for vertical and horizontal control.Butmore important than the thrustersandalltheotherhigh-techsystemsonthevehicleweretheweights.Thesubwas

equippedwith steelweights of 600 tomore than 1,000 pounds (270–450 kg).Theseweightswouldtakethesubdowntothebottomattheappropriatespeed;their subsequent release would bring the sub back to the surface. There wasconsiderable concern about backup systems that would guarantee the weightswoulddropoff,andCameronandhisteamhad“designedabouteightdifferentways”tomakesuretheywould.Fitting into the cockpit was not easy. It was only 43 inches (110 cm) in

diameter, andCameronhimselfwas6 feet2 inches (188cm) tall.He loweredhimselfdownthroughthe400-pound(180kg)hatch,whichwasaboutthesizeofamanholecover,andassumedahunched,knees-upsittingposition,bendinghisheadalongthecurveofthehull,hisbarefeetpressingagainstthewarmsteel.Themothership,MermaidSapphire,rockedintheswellsbutheldpositionat

11°22'N,142°35'E,directlyabovethedeepestpitinthesea.Showtime.A lot was going through Cameron’s mind in the hours after midnight on

March26,2012,asheandhis teambeganfourhoursofchecks inpreparationfor the final descent. Two key members of the expedition had died in ahelicopter crash only weeks before. During test dives off Papua NewGuineawith the 3-D cameras, the entire electrical system had gone on the blink, thecarbondioxidescrubberhadfallenoffthecockpitwallintoCameron’slapandthere were software glitches. Plenty of rough weather and missed deadlinesmighthavecausedtheexpeditiontobepostponedindefinitely.Butthetestdivesto ever deeper trenches had already provided valuable scientific data, and thesub’strapshadscoopedupgiganticwhite-shellamphipodsthathadstrippedthebait—awholerawchicken—tothebone.Hopingtogetlucky,theypersisted.Shortlyafter5a.m.,Camerongavethesignalandtheshipboardteamletthe

subdrop—like a stone.Cameron seemedoutwardly calmbut confessed in his2013NationalGeographicarticle,“Iamwrappedinthesub,apartofitanditapartofme,anextensionofmyideasanddreams.”Cameronglancedatthedials:500 feet (150m) perminute. Is there toomuchweight on this? The subwasdesigned togodownandbackfast toallowmore timeon thebottom,butwasthistoofast?Theexternaltemperaturefellfrom85degreesF(29°C)atthesurfacetoanear

freezing35degreesF (1.7°C) as the subdescended into theblack.Cameron’sbarefeetturnedcoldagainstthesteel,andhestruggledtopullonhisneoprenebooties.Next,heslippedonaknittedhat,àlaJacquesCousteau,toinsulatehisheadasitrestedagainstthesteel.Despite the minor discomfort of being crammed into what some might

considernotmuchmorethanacoldcoffin,Cameronfeltathome.“Snug”wasthewordheused.Hehadexperiencedenough submarine travel that the space

feltfamiliar.Thecockpithadfourvideoscreensthatoccupiedhisfieldofvision;three displayed views from the external cameras, and onewas a touch-screeninstrument panel. It vaguely resembled a compact mixing studio or mobileeditingsuite.ForCameron,thatwasanotherkindofhome.Exceptfortheoff-and-onhissoftheoxygensolenoid,allwasquiet.Cameron

strainedtolookintotheblackness,butallhecouldseewasplanktonracingpast,illuminatedbythesub’spowerfulLEDsearchlights,partoftheexpedition’s3-Dfilmequipment.Havinggonethroughhischecklist,Cameronthoughtabouttheintensepressurebuildingoutsidethesubandwhatwouldhappenifthevehicleweretospringaleak.“IfDeepseaChallenger’shullfails,Iwon’tfeelathing,”hewrote.“It’llbeaCUTTOBLACK.”At27,000feet(8,230m),90minutesintothedescent,Cameronbegantodrop

someoftheballast.Fromtheinitial3.5knots,heslowedto2.8knots,then2.5knots.Ashenearedthebottomat35,600feet(10,850m),heusedthethrusterstolimitthespeedtohalfaknot.Thealtimetershowedthebottomtobe150feet(45m)below.Heturnedon

allthelightsandstartedthecamerasrolling.At 60 feet (18 m) away, he observed a “ghostly glow” reflecting off the

bottom. He hit the vertical thrusters, braking ever so delicately. A faintdownwashseemedtocomefromjustbeneaththevehicle.Cameronaimedthespotlightacrosstheseafloor.Itburnedaholethroughthe

blackness,thewatersurprisinglyclear.Lookingallaround,thefilmmakercouldseenothing.Hefoundthebottomtobe“utterlyuniform,devoidofanycharacterbut the absence of character,” different from seafloors he had seen on all hispreviousdives.Withinseconds,hetoucheddownat35,756feet(10,898m).Thevehiclesank

aboutfourinches(10cm)intotheooze,andthesedimentdrifteduplikeafogmachine.Hewas23miles(37km)eastofwhereWalshandPiccardhadlanded.Itwas7:46a.m.,amere2½hourssincehehadbegunhisjourneytothebottomofthesea.The Mermaid Sapphire, nearly seven miles (11 km) above, made contact.

Cameronacknowledged thathe’d reached thebottomandallwas fine.Afterasharedmoment of relief and celebration, tingedwithwarmth for all who hadworked tomake thismoment possible,Cameron got busy, knowing hewouldhavejustfivehoursonthebottomtoexplore,collectsamplesandmakethemostof this extraordinaryopportunity.First, hedeployed the external arm from thesciencedoortotakeasedimentcoresample.Butonlyminutesafterbringingthesampleonboard, thehydraulicsystemstarted leaking, thearmandthesciencedoormalfunctioning.Unabletotakeanymoresamples,Cameronstartedinching

acrossthehadalbottom.Helatersaiditwaslikedrivingonnewlyfallensnow,withtheoddamphipodfloatingpastlikeawaywardsnowflake.Cameronturnedtolookoutthewindowandcontemplatethe“stillnessofthis

alienplace.”Chuggingalong,hewasshockedthathecouldseesofewsignsoflife,beyondthesnowyamphipods.Hefeltasifhehadgonetoaplacebeyondtheverylimitsoflifeitself.Hephotographeda“gelatinousblob”onthebottomandadarkscar thatmighthavebeen thehomeofa sedimentworm.Theblobturned out to be a giant single-cell amoeba, a so-called xenophyophore. Heobservedwhatlookedtobeanewsquidwormspecies,awormthattakesontheappearance of a squidwithmodified feeding appendages.And therewere seacucumberseverywhere,includingaspeciesunlikeanythinghe’dseenbefore.Nospecies can be identified as new, however, unless it can be collected andexamined. Still, Cameron was banking on the single sediment sample he hadtaken,hopingitwouldrevealsomethingmore.As the sub slowly headed north, Cameron moved gently up and along the

ridgesofaslope,lookingforrockyoutcroppingswithsignsoflife.Nothing.Hewasnowamileawayfromhislandingplaceandjustunderthreehoursintotheexpedition.Hebegantoworryabouthisbatteriesrunninglow;thecompasswasblinkingoff andon.Then the sonardied.When twoof the starboard thrustersfailed, Cameron found it hard to control the sub. The extreme pressure wastakingitstoll.Hepressedon,butwhenthesubabruptlylurchedtotheright,hediscoveredthathislaststarboardthrusterwasgone.Reducedtoturningincirclesandunabletotakesamples,Camerondecideditwastimetoabort.HecalleduptotheMermaidSapphire.Hewasmorethantwohoursshortofhisplannedstayonthebottom,butitwastimetoheadforhome.Flippingtheswitchtodroptheweights,Cameronshotupsuddenlyandfelta

senseof relief that themechanismworked.Thebottomdroppedaway,and thespeedquicklybuiltupto6knots, thefastest thesubhadevertravelled.Inlessthan90minutes,Cameronreachedthesurface,openedthehatchandsmiledathisteam.Cameronwasnowofficiallythe“kingoftheunderwaterworld.”Atouching

moment occurred shortly after his arrival back aboard theMermaid Sapphire.RetiredU.S.NavyCaptainDonWalsh,whohaddescendedtoChallengerDeepin 1960,was there to congratulate him and “welcome him to the club.”AfterPiccard’sdeath,Walshwastheonlymanalivetohavevisitedthebottomoftheocean.Nowtherewasonemore.In fact, though rarely reported,neitherCameronnorWalshandPiccardhad

actually reached the very bottom of theMariana Trench. In 1957, the SovietvesselVityazrecordedadepthof36,201feet(11,034m),whichwasdubbedthe

MarianaHollow.In2009,however,inperhapsthemostdefinitivemeasurementto date, the R/V KiloMoana, mother ship of the Nereus ROV, used a sonarmultibeam bathymetry system developed for deep-water mapping to record aspot in the trench that is 35,994 feet (10,971 m) deep. The accuracy of thismeasurement is towithinplusorminus72 feet (22m).Thismaybe themostreliableestimateof thedeepestpartof theocean. If so,nohumanhasmade itthereyet—close,butnotquite.Yetevenwiththeseexplorationsofthehadaldepths,thebeliefhaspersisted

that the deep trenches and the abyssal plains harbor a “reduced”monotonousfauna.Yes, there is life,but itappears tobefairlysimilar fromplace toplace.Comparedwith the rich intertidal zonesand the surfaceof the sea, thebottomseems to be something of a muddy desert populated by little more than seacucumbersandworms.Despiteeffortstofinddiversityandproveotherwise,theChallengerExpedition (1872–76) had “established” this as “fact,” andPiccardand Walsh’s dive, as well as Cameron’s, had not dislodged that overallimpression.AndalthoughCameron tookpictures,hewasunable tobringbackmorethanonesampleoftheooze.In the mid-1960s, however, five years after Piccard and Walsh visited

Challenger Deep and nearly 50 years before Cameron’s expedition, thismisconceptionwaschallenged.BiologistsRobertHessler andHowardSandersof the Woods Hole Oceanographic Institution did extensive dredging andtrawlinginthedeep-searegionsbetweenCapeCodandBermuda,andwhattheyfoundsurprisedeveryone.Their“epibenthicsled”wasabletocaptureanimalsjustaboveandbelowthe

oceanbottom,aswellason thebottom itself.Also, themeshwasmuch finer.HesslerandSandersfoundliterallyhundredsofspecieswhereoneortwowerethought to exist. Therewere tens of thousands of species, not a few hundred.Although the number of species declined as the sled went ever deeper, thenumberwasmuchhigherandthediversitygreaterthanhadbeenimagined.HesslerandSanderswentonlyasfarastheabyssalplains.Someresearchers

believe that the number of individuals and the diversity of species, aswell asmicrobes, in thehadalzonetrenchesmaybegreater thanonmanypartsof theabyssalplains,whichwouldreversethegeneraltrendofdecliningdiversitythedeeper you go.The thinking is that since trenches aremainly located close tolandandbeneathproductivesurfacewaters,therainofnutrients,includingdeadbodiesfromthesurface,isgreaterthanitisfartherouttoseaabovetheabyssalplains.Afterthenutrientsfall,theybecome“trapped”inthetrenches.Life-forms do vary from trench to trench. Deepsea biologists have found

different species of sea cucumbers and othermud-eaters in different trenches.

Thismakes sense, as the trenches are deep holes or valleys that function likeislandsseparatedfromoneanotherbyconsiderablestretchesofabyssalhillsandplains. The result is reproductive isolation—one of the evolutionary processesthatcreatenewspecies.Themorescientistsexploretheabyssalplainsandhadaldepths,themorethey

find new species of echinoderms, the phylum that includes starfish, seaanemones and sea cucumbers. To be fair, there are more echinodermtaxonomiststhantaxonomistsforothergroups.Thebottommegafaunaathadalandabyssaldepthsiscomposedlargelyofechinoderms.ToouriMonstercam,itseemsagraydesert,theoddseapenstandingnearlyafoot(30cm)high,likeafeatherstuck in theground.A little larger,ata foot (30cm)ormore long, thebrisingid starfish, with its curved-up arms, resembles a sun-beached headlessskeleton,orat least its ribcage.Therearealsocnidarians, suchasChitoanthisabyssorum, andmollusks. One well-adapted fish uses its fins to stand on thebottom.Thetripodfish(Bathypteroissp.)isnegativelybuoyant,lackingaswimbladder or other means of buoyancy. But more than anything, there are theholothurians,orseacucumbers,onthebottom.Andtheyarenotonespeciesbutmany.Theverybottomis,inmanyways,the“kingdomoftheseacucumber”or,for

thoselessromanticallyinclined,thekingdomofthemud-eaters.Theseso-calledholothuriansfeelathomeontheseafloorandhavediversifiedintoat least900species.Manyare,indeed,cucumber-shaped,amblingacrossthebottomatafewyards per hour, their multiple feetlike protrusions moving them along in arhythmicswayingmotion.Headlesscreaturesequippedtoinchalongthebottomortolaunchthemselves

into thewater column, sea cucumbers often travel in great herds, “galloping”across the abyssal plains and the bottom of the hadal trenches. Other seacucumbers look more like mini flying saucers except when they move,undulatingover the seafloor likeotherbottom flatfish adapted to look like thebottom topography.Usually gray, brown, black or olive green, sea cucumberscangrowsix feet (2m)ormore in length.The longestare found in shallowerwaters,wheretheymoveonorjustabovetheseafloorlikeheadlesssnakes.Thehadal sea cucumbers are smaller, some littlemore thanan inch (2.5 cm) long,and aremore groveling—truemud sloshers. Looking closely, it is possible todiscern the front end—on the rare occasion when it’s not buried in the mud.There are no eyes, but feathered tentacles surround the mouth, and in somespecies, the tentacles are periodically inserted into the mouth after extractingjuicynutrientsfromthemud.

Theseacucumberhasmanystrangehabits.Forstarters,itbreathesthroughitsanus.Whenyou’reaplodding,toothlesscreaturethatmusttakeurgentevasiveaction,desperatemeasuresaresometimes

required.

Theseacucumberhasmanystrangehabits.Forstarters,itbreathesthroughitsanus.Likeitscousinstarfish,theseacucumbercanregeneratecertainbodypartsif needed, such as the digestive tract, and is able to expel its guts and otherinternalorgans throughitsrearend, thengrowanewset in thespaceofafewweeks.Thisbehaviormaybeawayofdistractingorfrighteningoffapotentialpredator as the sea cucumber makes its getaway. When you’re a plodding,toothless creature thatmust takeurgent evasiveaction,desperatemeasures aresometimesrequired.The prevalence of sea cucumbers on the ocean bottom and their variety of

shapesandsizeshave ledsomebiologists tosuggest thatJacquesPiccardmayhave seen a sea cucumber, not a flatfish, when the Trieste set down on thebottomofChallengerDeep.Perhaps thebottom sedimentwas sodisturbedbythelandingofthebathyscaphethatPiccarddidn’tgetaclearview.ThesesamebiologistsarefondofpointingoutthatPiccardwasnotabiologist,andneitherisJamesCameron,thoughCameronatleasthadcameradocumentationofwhatheencountered.InPiccard’sdefense,hehadmoreexperienceinthedeepthananybiologistoranyotherpersonaliveatthetime,butit’salsotruethatfishhavenotbeenfoundatthatdepthonanyothertriptoChallengerDeepsince,whetherbyremoteormannedvehicle.Theseacucumberisafantastic,fascinatingcreature,worthyofcuriosityand

understanding,althoughitishardlyamonster.Orisit?Fromitsperchontheseafloor,theiMonstercamturns360degrees,andfrom

every angle, sea cucumbers are slowly but steadily approaching to investigatethis alien presence. Strange mouths open and close all around, coming evercloser, looming above the small camera. One sea cucumber startles another,whose guts promptly shoot out.And then, in the commotion, it happens. Thelargest sea cucumbernudges thedevice, and the feathered tentacles around itsmouthticklethelens.Wearetoocloseforcomfort.Theneverythinggoesdark.

Nothing down here on the bottom escapes attention for long. And we findourselves in the middle of a biology lesson that shows how everything isinvestigated,recycledandalmost,butnotquite,devoured.Ofcourse,thereisnotmuchnutritionalvalueinthespeciesiMonstercam,and

theseacucumbersoongoesbacktofilteringmud.Butanythingthatarrivesonthebottom fromabove,particularly anythingdifferent, ispromptly filtered foranynutritionalvalueitmightcontain.Hadwebaitedthecamera,wecouldhaveexpectedtinyscavengingamphipodstodescendenmasseaswellasvariousfish,such as grenadier fish, all drawn to the smell of food in the water. With itsflashingon-offlight,itshugeeyelensanditspartlysilver-whiteandpartlyblackcoloring, the iMonstercam arguably shares something of the deep-sea creaturemorphology. Much stranger deep-sea creatures exist in the land of the mud-eaters,wheretheseacucumbereverroams.Indeed, the sea cucumbermaybe the kingof the deep: the once and future

residentofthisland,thrivinginthehadaltrenchesandslopesandontheabyssalplains.Apostscript toCameron’s2012expedition:The sedimenthe collectedwas,

indeed,fullofmicrobes—bacteria,archaeansandmore.A2013paperinNatureGeosciencebyRonnieGludandhiscolleaguescompared theChallengerDeepmicrobeswith those in a nearby 19,685-foot-deep (6,000m) site. They foundtwiceasmuchmicrobialactivity in thesedimentsof theMarianaTrenchas intheshallowersite,andtherewasanelevatedrateofdepositionoforganicmatter,with oxygen consumption occurring twice as fast as in the shallower site.Perhapsthemicrobesarethetruekingsofthedeepsea?

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Siphonophoresarecomplexcnidarians—colonialanimalscomprisingspecializedzooidsthatareattachedtooneanotherratherthanfunctioningindependently.Thisspecies(Stephanomiaamphitridis)livesdeepintheAtlantic.

Thisclose-up—froma2012GulfofMexicoexpeditionsponsoredbytheNationalOceanicandAtmosphericAdministration(NOAA)—showsatwo-inch-long(5cm)brittlestarwrappedaroundaparamuricidcoral.Thebrittlestaroftengrabsfoodparticlessuspendedinthewater,butitalsofeedsonpolyps.Notethatthecoralpolyps,theyellowbudsonthebranches,areretracted.

UsingitsstickytentaclestoensnareahatchetfishatDragon’sHead,intheGulfofMexico’sDeSotoCanyon,adeepwateranemonepullsitevercloserbeforedevouringit.

TheWoodsHoleOceanographicInstitutiondeploysaremotelyoperatedvehiclecalledNereus,shownherewithdiversintheCaymanIslands.In2009,theNereusbecamethethirdofonlyfourvehiclestodatetovisittheMarianaTrench.

Abarrel-shaped,planktonictunicate,thesalpisamarineinvertebratethatmaylivealoneorjoinupwhenphytoplanktonisabundant.Itmovesandfeedsbycontractingandpumpingwaterthroughitsgelatinousbody.Here,acolonyof12salpsdriftsthroughthetropicalPacific,nearthePhoenixIslands.Notethateachsalpiscarryingoffspring(thetubesattachedtotwocircles).

Duringa2007CensusofMarineLifeexpedition,AmericanandFilipinoresearchersfoundthisfour-inch-long(10cm)worm(Teuthidodrilussamae)1.7miles(2.7km)belowthesurfaceoftheCelebesSea.Theycalleditthe“squidworm”becauseofitssquidliketentacles,anditturnedouttobeaspeciesnewtoscience.

Theundersideofthedeep-seaseacucumber(Deimavalidum)revealsastiffbodystructurewithrough-texturedskincoveredinspicules.ThisonelivesontheMid-AtlanticRidgeatadepthof8,200feet(2,500m).

Thetransparentbodyofthisdeep-seaseacucumber(Peniagonediaphana)showsoffthesimpleseacucumberanatomy:amouthatoneendandananusattheother.Thisspecieslivesatdepthsofapproximately8,200feet(2,500m)andisanactiveswimmer.Itprobablyspendsmostofitstimedriftingoverthe

seafloorwithitsheaddirecteddownward,readytoingestfallingdetrituswhenitlands.

PARTTWO

Previous page:A ghostly shoal of bigfin reef squid (Sepioteuthis lessoniana)charges through tropical waters off Sulawesi, Indonesia. By controlling thechromatophoresthatcoveritsbody,thisspeciescanalmostinstantlychangeitsskinpatternandcoloration.Skincellsknownasiridophores,mainlyonitshead,produceiridescentmetallicgreensandredswhenilluminated,whileothercellssuchasleucophoresreflectambientlightandareusedforpassivecamouflage.Inwhitelight,thissquidbecomesallwhite;ingreenlight,itbecomesgreen,andsoon.Whileitscamouflageiseffectiveformostpredators,thebigfinreefsquidisfishedandeateninlargequantitiesthroughoutSoutheastAsia.

Atupto9.8feet(3m)long,thesandtiger,orgraynurse,shark(Carchariastaurus),hasapointyhead,smalllidlesseyesandprotrudingteeth—thesortofphysicalprofilethatisthestuffofbaddreams.Yetitisarelativelyplacid,slow-movingsharkwithnoknownhumanfatalitiesonitsrecord.

AAFish-Eat-FishWorld

N UNABASHEDLY cheesy sea-monster movie directed by RennyHarlin and released internationally in 1999–2000, Deep Blue Seamade theoriginalJaws seemalmost tameand scientifically saneby

comparison. In this entry in the canon of murderous shark films, the actionoccurs within the walls of a marine research station. Here, scientists havegeneticallyengineeredthefast,extra-toothymakoshark(theJawspostershark),increasing the size of its brain in order to produce chemicals that will cureAlzheimer’sdisease.Whenthegiantsupersharksgoontheinevitablerampage,werealize,presto,thatwe’rewatchingageneticallymodifiedsharkhorrorstory—JawsindoorsmeetsDollythesheepwithbigbrains,akaSharkenstein.Flash forward to 2012 andAttack of the Jurassic Shark, inwhich scientists

manage to awaken an extinct megalodon shark, bigger and badder than anysharkeverknown,withsimilarlydisastrousresults.Butintheseandsome40othersharkfeaturefilmsbetweenJawsandJurassic,

wehave,moreor less, the sameoldplot,with the sameoldvillainous sharks.Killer shark films retain their deep hold on the public, but the sharks keepgettinglarger,theteethsharper,thebloodredder,thechasemoreprevalentandpersistentandthehumanvictimsmoreterrified,mauledandmutilated.Inreality,a fatalsharkattack isa rareevent.Evenso,beingcheckedoutor

pursued by a shark can be a terror-inducing experience. But these filmsexaggerate all the essential details to turn a simple fact into the stuff ofHollywoodbloodbathnightmares.At a timewhen thenumbersofmany sharkspeciesareseverelyreducedandseriouslyendangered,dueinparttothemediahypeandhysteriastokedbysuchfilms,itisironicandinpoortastethatin2014—40someyearsaftertheoriginalStevenSpielberg-directedJaws,plussequels,TVspin-offsandrip-offs—thereisanaverageofone“majormotionpicture”ayearbentonprovokingandexploitingthehumanfearofsharks.ThelatePeterBenchley,whowrotethebookonwhichtheoriginalJawsand

someofitssequelswerebased,apologizedininterviewsandarticlesyearslaterformaking the shark into awillful villain.Benchley acknowledged there’s no

evidencethatsharks—oranyotherseacreaturessuchasmightbefoundinhisotherworksTheDeepandBeast—harborgrudgesandseekouthumans.Still,headmitted,“Jawsputmykids throughcollege,” sohemightnothavewritten itanydifferently.

Overthepastdecade,sharkswereresponsibleforanaverageof75attacksaroundtheworldandfewerthanfivefatalitiesperyear.Humansarefarmorelikelyto

drownintheseaorgetstruckbylightning.

Jawswasnotthefirstdiatribeagainstsharks.Beforethemoviescamealong,many commentators proved farmore vicious toward sharks than sharks couldever be toward people. Witness Capt. William Young’s 1933 book Shark!Shark! Author and longtime shark defender Richard Ellis calls Young theultimate shark hater and this the ultimate antishark book—one edition wasactuallyboundinasharkskincover.Youngspentmostofhislifebad-mouthingsharksandkilling them.YetYoungandothervilifiers, suchasHarlinand thereformedBenchley,clearlydrewonthelong-standing,possiblyprimevalfearofthisanimal.WhenBenchleyarguedthathedidn’tinventthefearandhatredofsharks,he

was correct, but characterizing these creatures as primitive, mindlesslymalevolentand“perfectlyevolvedeatingmachines”didnothelp.ItisfairtosaythatsharkshadrecededsomewhatfromthepubliceyeintheyearsbeforeJaws-mania and that the intense interest sincehasbeen largely, thoughnot entirely,negative.Manymillionsofpeoplesafelyswim,diveorsurfeveryyearinwatersinhabitedorvisitedbysharks.Overthepastdecade,sharkswereresponsibleforanaverageof75attacksaroundtheworldandfewerthanfivefatalitiesperyear.Mostoftheseweresurfersofonekindoranother,probablyvulnerablebecauseof the amount of active time surfers spend in the surf zone, where theymayappeartobesharkprey.Thefatalityrateoverthepast100years,however,hasfallensteadilythanks,inpart,toadvancesinbeach-safetypracticesandmedicaltreatment and to increased public awareness of avoiding potentially dangerousareasandsituations.Yetevenintheyear2011,whichsawa20-yearhighof12fatalities, humans are far more likely to drown in the sea or get struck bylightning. Still, that has not stopped the media “feeding frenzy” that follows

everysharkattack.The current annual shark slaughter has been estimated at 26 million to 73

millionsharksperyear,withanaverageof38millionayear.Otherstudieshavesuggestednumbers that averageabout100millionperyear.These sharksdiedforsharkfinsoup(thedorsalfinonly),forjewelry(theteeth),formedicineandcosmetics(theliverandcartilage),forcommercialproducts(thehide),forfood(the flesh), by accident (in nets set for other fish) and from sportfishing andtargetederadicationprograms.ThebestguessisthatsharksofftheeastcoastoftheUnitedStateshavebeenkilledatroughlytwicetheratetheycanreproduce.And in some parts of the world, the killing rate is many times the rate ofreproduction.Many countries are now taking steps to protect white and other sharks by

outlawing “finning” (killing sharks for shark fin soup), placing quotas oncatches,settingminimumsizesforcapture,restrictingthetakeofcertainspeciesandestablishingmarine sanctuaries tohelpprotect sharkpopulations. In2009,Palau,intheCentralPacific,becamethefirstcountrytobanallsharkfishinginits national waters. Since then, Maldives, the Bahamas, Honduras, the CookIslands,FrenchPolynesia,TokelauandtheMarshallIslands,amongothers,havecreated their own shark sanctuaries, the largest single one being FrenchPolynesia,at1.9millionsquaremiles(4.9millionkm2).Yetwithoutenforcementoftheselaudablemeasures, thedaymaynotbefar

offwhenallthatremainsofthebigpredatorsharksarethosemodelsdevelopedby filmproducers: themechanical sharknamedBruceandhis fiberglass, latexandrubbermatesondisplayattheUniversalStudiosthemeparksinCaliforniaandFloridaandtheassortedsharkrobotsstoredinHollywoodbacklots.Fromascientificandconservationperspective,thelossofsharkspeciescould

have important repercussions. Studies of their acute sensory and extrasensorysystemsforhuntingandnavigationmay lead tousefulmodels formedicalandcommercial applications. From an ecological perspective, sharks play a top-predator role in the sea,helping, asallpredatorsdo, tokeep smallerpredatorsandpreyhealthyandtomaintainthebalanceofecosystems.More than anything, however, the great tragedy of the Hollywood

phenomenonisthatthemagnificentcharacterofthewhitesharkandotherlargepredatory sharks has been clouded, distorted, diminished and sometimesdemolished. To many, the shark has become an object of fear, hatred andderisionor,worse,acartoonvillain.Butlet’slookbeyondthebloodymovies,novelsandpublicmisconceptionsto

uncover the true meaning of the predator-prey relationship. That most basichierarchy in the natural world has a simple, matter-of-fact elegance based on

Darwin’stheoryofevolutionthroughthemechanismofnaturalselection.Inthesea, this is typified by big fish eatingmedium-sized fish that, in turn, devoursmallerfish.Butthefishthatareabletobreedbeforebeingeatenpassontheirgenes to the next generation. The predator tends to take the weak or surplusyoungofthepreyspecies,thuskeepingthepreypopulationhealthy.Ofcourse,predatorsneedhealthyandnumerouspreytoo.Supreme on this list, thewhite shark is among the top sea predators, along

with the spermwhale and the killerwhale, or orca.Yet things are not alwaysstrictlyhierarchicalonthebasisofsizealone.Therearesmallbig-mouthedfishthat can devour fish larger than themselves.When large animals such as thewhite shark, the killer whale and the giant squid eventually die, they becomefood not for predators but formicrobes—the bacteria,worms and other smallanimalsthatpreyuponthedeadinwhatmightbecalledthetriumphofthelittlestuffthatrunstheworld,afateinescapableforall,includinghumans.In any case, these simple hierarchies, or food pyramids, as ecologists call

them,notonlyreveal feedingrelationshipsbuthintat theflowofenergyfromone feeding, or trophic, level to another as well as the constant recycling ofnutrients through thevarious biogeochemical cycles.Energy flowandnutrientrecyclingoccurintheseajustasonland,butonamuchgranderscale.Withoutthesecycles,lifeonEarthandintheoceanwouldgrindtoahalt.Let’sgo to thesourceofsomeof thesestoriesandseewhere they lead.We

will explore the food pyramids of sixmajor groups of predators. Besides theobviouschoices—carnivoroussharks, squid, spermwhalesandkillerwhales—we will look at predator-prey dramas in the lives of small crustaceans calledcopepods, jellyfish, planktivorous (plankton-feeding) sharks and deep-seadragonfish.Butfirst,we’llmeetthephytoplankton,thebasisoflifeinthesea.

♦

Awhiteshark(Carcharodoncarcharias),knownpopularlyasthe“greatwhiteshark,”leapsclearofthewaterinpursuitofpreyinFalseBay,SouthAfrica.Inrecentyears,inanattempttoavoidthenegativeculturalassociationsestablishedinHollywoodmoviesandpressstories,sharkresearchersandconservationistshavetakentocallingthisbigfishsimplya“whiteshark.”

Sharkfinsforsharkfinsoupareprocessedatashark-finningcampinMagdalenaBay,BajaCaliforniaSur,Mexico.Thespeciesshownhereareblueandmakosharks.Millionsofsharksarebeingkilledeveryyearfortheirfins,amassivewastefulfisherythatwillsoonend.Theonlyquestioniswhethersomesharkspecieswillbecomeextinctfirst.

Photographedatnightinnaturallight,thedisruptionofthousandsofbioluminescentphytoplanktoncalleddinoflagellates(Pyrocystissp.)causesflashingbluelightthatisclearlyvisibleintheswimmingtrailsoffish,sealsandwhalesandinthewavesbreakingonthebeach.

O

PlanktonicDramas

URBASICstorybeginsnearthesurfaceoftheseaonthefirstwarmspringday innorthern temperatewaters.Let’ssay it is inRosewayBasin, in the northwestern North Atlantic, 40 miles (65 km) off

southernNovaScotiainthenorthernGulfofMaine.Lightwinds,calm,almostflatseasand,crucially,abrightsunnydaysetthescene,forjustasonland,thesunisthegreatenginetokick-starttheprocessoftheannualrenewaloflifeafterwinter.By latemorning,with thesurfacewatersstarting toheatup in thesun,thediatoms—amajor classofplantlikeplankton,orphytoplankton—thathavebeen, in effect, hibernating in deep waters through the winter begin toincorporatevariousnutrientsstirredupbywinterstormsandupwellingcurrents.Within a fewhours, the first cell divisions occur.Onediatombecomes two

diatoms,which,bymidafternoon,become fourdiatomsand,by theendof theday,eightdiatoms.Eachdiatomisagreenishbrowncellinasortofsee-throughdecorativecasemadeofsilicondioxide—thesamematerialusedtomakeglass.Thecase isnotpartof the livingplantandvarieswidely inornamentaldesigndependingon the species. Its relative transparencyallowssunlight topass intothecellthathousesphotosyntheticorganelles.Thenearlyinvisiblecasemayalsohelp the diatom avoid being seen and eaten. Single-cell diatoms often livetogetherinchains.Eveninchains,theyaremicroscopic.Ittakesmanythousandsofdiatomstoturnthewatergreenishbrown,andbythat time,otherspeciesofplankton are also growing in great numbers. This growth spurt is known as aplankton“bloom.”In amatter ofweeks following the spreadof thediatoms in this part of the

Atlantic, the dinoflagellates come alive and similarly grow and spread. Eventhoughtheyaresomewhatlikeplants,dinoflagellates,unlikediatoms,canmovethroughthewater.Usingtwowhiplikeflagella,theykeepthemselvesinthesunduringtheday,butatnight, theyswimdown30feet(9m)ormoretopickupnutrientsthatthediatomsareunabletoreach.Dinoflagellatesareasolitaryclassofphytoplankton,reproducingbycelldivision,justasthediatomsdo.Insteadof

the diatoms’ silicon dioxide covering, however, dinoflagellates are oftenarmored with cellulose. Some dinoflagellates are responsible for thebioluminescenceseenatnightinbreakingwaves,boatwakesandfishtrails.

Dinoflagellatescanbemoredangerousthansharks,butHollywoodhasyettocastdinoflagellatesasalethalkillingmachine,sotheyremainunexploited,goingabouttheirnastybusinessinrelativeobscurity.

Butdinoflagellatesalsohaveadarkside—theyare thedeadlynightshadeofthemarineworld.Whencertaindinoflagellatesreproduceingreatblooms,theyturnintoredtides,whichcanmakethewateritselfblood-red.Thedinoflagellatespecies thatcausered tidesproduce toxins,suchassaxitoxin,whichattack thenervous systems of fish and cause mass mortality. As bacteria work todecompose thedead fish, they consumeoxygen, leaving thewaterdepletedofoxygen,whichcanalsoleadtomassivefishkills.Other dinoflagellate toxins are absorbed by mollusks, such as clams and

mussels.Whilethetoxinsdon’tharmthemollusksthemselves,anyfish,marinemammals or humans that consume themollusks can suffer partial paralysis ordeath.Dinoflagellates can bemore dangerous than sharks, butHollywood hasyet to cast dinoflagellates as a lethal killing machine, so they remainunexploited, going about their nasty business in relative obscurity, beyond theoccasional shellfish-harvesting closures due to contamination.Of course, theirroleinthefoodpyramidhasattractedevenlesspublicattention.Stillotherphytoplanktonbecomeactiveandspread.Hundredsofspeciesina

given area create amixed-plankton surprise soup. Theword plankton actuallyreferstofree-floatingorganismsinthesea,asopposedtobenthic(attachedtothebottom)andnektonic(free-swimming)organisms,andforallpracticalpurposes,plankton describes almost any living thing in thewater column that can’t getaroundunderitsownsteam.Formany,planktonissynonymouswiththesmallstuffinthesea,andthegreatmassofitiscertainlytiny—infact,muchofitisinvisibletothehumaneyewithoutmagnification.Yetplanktonisageneral,evenrelativeterm.Certainplanktonicanimalsand

eventheplantlikeorganismsmovearoundalittle,thoughtheyaresubjecttothecurrents and other whims of the sea, much more so than nektonic creatures.

Besidesthelarger,better-knowndiatomsanddinoflagellates,bothofwhicharelargeenoughtobecaughtinfinenetsandarethuscallednetplankton,therearemuch smaller plankton. Current advances in observation methods reveal theimportance in terms of biomass as well as photosynthetic activity of the so-called nanophytoplankton and picophytoplankton, which are 10 to 100 timessmallerthannetplanktonand1,000to10,000timessmallerthancertainjellyfishplankton,thelargestplankton.By June, the late bloomers—nanophytoplankton called coccolithophores—

become more active. The tiny cells are surrounded by chalk shields, orcoccoliths. Incertainyears, thesephytoplankton reproduce rapidly, turning thesurface of the sea patchy white from the coccoliths they deposit. But usuallywith coccolithophores and other phytoplankton, the most prevalent color isgreen. Blue-green algae—actually cyanobacteria—and the very tinyprochlorophytes are among the most numerous of all marine organisms.Together, they help to create the greenish color mariners see when they sailthrough productive areas in early summer and the telltale color captured insatellite images.The time-sequence satellitephotosof theNorthAtlantic fromspringtoearlysummerreveal thegreatmarchofgreentowardtheNorthPole,advancingdaybydayandweekbyweekalmosttotheedgeoftheicecapsattheheightofsummer,beforeretreatingagain.Thisgreenisthechlorophyllintheplankton.Chlorophyllisthemoleculeused

intheprocessofphotosynthesistoharnesssunlightandconvertcarbondioxideandwaterintocarbohydratesandoxygen,twothingsessentialforlifeonEarth.Green on land and in the sea is the color, the very stuff of life. Withoutphotosynthesis, the classic sea and land monsters would never have evolved.Lifeitselfwouldhavegonenowhere.Phytoplanktonformsthewidebaseofa thousanddifferentfoodpyramidsin

thesea.Itistheprimaryproducerinallthecomplexenergy-flowscenarios.Asenergymovesfromthesunto theproducer to theconsumers—bothherbivoresandcarnivores—inasequenceoftypicallytwotosixlinks,itdissipatesthroughheatlossandmetabolicusebyvariousorganisms.Itisestimatedthatproducerscaptureaslittleas1percentofthesun’savailableenergyandpassalong5to20percentofthatenergyateachsucceedinglevel,fromtheproducerphytoplanktonto the herbivorous zooplankton, followed by the carnivorous fish, squid andother animals and, finally, the top carnivores in every system. Ecologistsestimatea10percentenergytransferupeachlinkofthefoodpyramidorchain:10 percent of 10 percent of 10 percent of 10 percent of 1 percent of the sunequals0.000001,orapproximatelyonehundred-thousandthofthesun’senergyleft by the time it gets towhite sharks, killerwhales, seals and sea lions.No

wondertheyneedtoeatsomuch.The energy loss in the sea is akin to the heat loss in the average suburban

home,butnutrientrecyclingpresentsadifferentstory.Unlikeenergy,thereisafar more limited supply of available nutrients, which are crucial for life andgrowth.Variousbiological,chemicalandphysicalprocessesconstantly recyclenutrients.Eachnutrientnecessary for lifehas itsowncycle, from thenitrogenandphosphoruscyclestothewell-knowncarbonandhydrologic(water)cyclesthatworkonaglobalscalewithprofoundimplicationsforworldclimate.One other essential component contributes to the trophic structure, or food

pyramid: the decomposers. Mainly bacteria and other microbes, thesedecomposersbreakdowndeadorganismsandreleasesimplemoleculesthatcanbeusedagainbyboththeproducersandtheconsumers.Themoleculescontaintheessentialnutrientsofcarbon,nitrogenandsulfur.Thedecomposersworkateverylevelofthefoodpyramid.Ofcourse,theseacontainsthousandsoffoodpyramids,andmanycrisscross

oroverlapwithinagivenecosystem.Asoceanographersunravel the importantrolesofeversmallernanophytoplanktonandpicophytoplankton,ourknowledgeof the base grows. The classical food-pyramid model of the sea started withdiatomsanddinoflagellatesbeinggrazedbycopepods.Butnewcrucialfirst-steplinks have emerged between tiny ciliates and flagellates and the microscopicplankton. The classical model still holds for many parts of the ocean, but inlarger regionsof theopen sea, away fromcoastal andupwellingareas,wearejustbeginningtorecognizetheimportanceofthesemorebasicbuildingblocks.

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At12,000timesmagnification,ascanning-electron-microscopephotographrevealsthepotentialkillerdinoflagellatephytoplanktonresponsibleforredtideevents.Aredtideiscausedbyanoverproductionofcertaindinoflagellates.These,inturn,producetoxinsthatenterthefoodchainandattackthenervoussystemsoffish,seals,whalesandevenhumans.

“Blue-greenalgae”isacommoninformaltermforwhatisnowcalledcyanobacteria.Amongthemostnumerousformsoflifeinthesea,cyanobacteriaarephotosyntheticbacteriabelongingtotheprokaryotes

Z

TheCosmopolitanCopepod

OOPLANKTONarethesmallestgrazersandhuntersinthesea.Likethewordplankton,zooplanktoncanbeaverygeneralcatchallterm.Itincludes tiny crustaceans,worms andmollusks, aswell as the larval

stages ofmany seafloor species, such as clams and shrimp.Thus zooplanktonrefers tocreatures that live temporarily in theplanktonstageandtoothers thatspend their entire lives as plankton and may undergo numerous planktonicmetamorphoses.Zooplankton function as the intermediate trophicgroup in theocean,carryingthesun’senergyfromthephytoplanktontofish,squidandevenwhales.Some of themost abundant animals in the world—and themost numerous

zooplankton in the sea—are the various species of copepods. Most areherbivorous, like cattle, though some are carnivorous mini-tigers, even eatingother copepods. Either way, in their quest to track down their daily meals,copepodsliveamorecomplicatedlifethandocattle.The main copepod across the temperate northern hemisphere is Calanus

finmarchicus. Growing up to almost ¼ inch (6 mm) long, an adult copepodweighs about 1/12,000 ounce (0.002 g). Thus it would take 12,000 copepodspiledontoascaletomeasureoneounce(28g).This northern copepod is strictly herbivorous. According to biologist Steve

KatonaatCollegeoftheAtlantic,onecopepodcoulddevourall thesingle-cellphytoplankton in half a cup of water in just one day. The copepod feeds bymovingitsappendagesbackandforthlikefanstocreatewatercurrents.Whenacandidate green phytoplankton cell moves within range, appendages calledsecond maxillae open like arms to ensnare the cell and move it up to theanimal’sgapingmouth. It is farmorework thanbendingdown toeatgrassorhay.

This1⁄28-inch-long(0.9mm)femalecopepod(Sapphirinasali)carriesherpreciouscargooftwoblueeggpouchesattachedtothesidesofherabdomen.

Fluorescentpinkcopepods(Caliguselongatus)parasitizethismalelumpsucker(Cyclopteruslumpus),orlumpfish,offEngland’sDevoncoast.

Acopepodmaynot lookdangeroustohumans,but tryscalingoneupafewhundredtimes.Onacold,darknightbeneaththeoceansurface,withacoupleofjeweler’s loupes attached to your eyes, a copepod coming at you with itscharacteristic jerky swimming behavior couldwell be considered fearsome. Itmight even offer filmmakers some replacement fodder for their tired shark-attackstorylines.Andtocertainphytoplankton,thecopepodisabsolutelylethal.The northern copepod’s complex life history is short yet dynamic.When a

typical male copepod meets his much larger mate, he doesn’t waste time onromance.Heclaspsthefemalewithhisfirstantennaeandhislastpairofthoracicappendages, using the appendages and a special cement to transfer his spermpackettothefemale’sreceptacleopenings.Fromeggtoadulthood,thereare12molts, or stages, which take about 2½ months to complete. With enoughphytoplanktoninthewater,thefirstcopepodsthatreachadulthoodinspringcanhave “grand-offspring” or even “great-grand-offspring” by the end of thesummer.Somecopepodshavemoveduptothenexttrophiclevel,becomingcarnivores

ofotherzooplanktonorevenothercopepods.Theevolutionary response is forsomecopepodspecies,bothpotentialpredatorsandprey,tooptforcamouflage.Aswithphytoplankton, thestrategyof relative transparency inmanycopepodsandotherzooplanktonspecieshelpsthemavoidbeingeaten.Still other copepods become parasites of fish. At least a thousand copepod

speciesspendtheir livesattachedvariouslytofins,gillfilamentsorotherbodyparts of a wide variety of fish. The Greenland shark—a creature we willencounterlater—hasacopepodlivingonitseyes,hangingfromthecorneas.Yetallisnottoothandclaw.Inthepast,itwasassumedinthe“carnivoreeats

herbivoreeatsplant”modelthatthephytoplanktonarecompletelydevouredbythecopepodsandthatthecopepods,inturn,areeatenbyotherzooplanktonandfish.Infact,despitetheextraordinarydensitiesofcopepods,itappearsthatmostofthetime,thephytoplanktonmanagetoliveouttheirseasonallivesandreturntheirnutrientstoberecycledwithouteverencounteringacopepod.

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J

JellyfishBidingTime

ELLYFISH can be benthic (attached to the bottom) or nektonic (free-swimming),sometimesalternatingbetweenbothlifestyleswithinasinglespecies.Still,thenektonicjellyfishtendtobeweakswimmersandwould

never challenge other creatures at a swim meet. Most jellyfish, in fact, areconfirmedmembersof theplanktonclub, laying to rest themisconception thatall plankton are small. One species of that jellyfish relative, the sometimesplanktonic,sometimesfree-swimmingsiphonophore,growsupto160feet(48.7m)longandcouldstretchoutinanOlympic-sizedswimmingpool.Jellyfish and siphonophores are grouped with the cnidarians—a diverse

phylumofsome10,000speciesthatincludesseaanemones,seapens,seafans,corals,hydrasandhydroids.Manypeopleconsiderspeciesinthisgroupamongthe most beautiful animals in the sea.Witness their elegant radial symmetry,their flowerlike poses and vivid colors. Typically, they do not search out andattack other life in the sea. They rely, instead, on water currents and on“mistakes,”or lackof due caution, on thepart of their haplessprey.They arepredatorswithwhatmight be called, in some cases, a terrible beauty: Severaljellyfishspeciesarehighlypoisonous,andtheirfiercereputationprecedesthemto such an extent that many people have developed an irrational fear of alljellyfish.One of the largest andmost dangerous jellyfish is the lion’smane (Cyanea

capillata). It feedsonsmaller fishbutcansubduefisha foot (30cm) long. Itsbell, or medusa, may span up to 7½ feet (2.3 m) in diameter, with tentaclesextendingdownwardfor100feet(30m)ormore.Thelion’smanejellyfishcanweighaton(900kg).AspecimenthatwashedashorealongMassachusettsBayin1870 stillholds thecurrent record.Sporting120-foot-long (37m) tentacles,this “monster” exceeds the recorded and putative lengths of the giant squidand thebluewhale,whichalways receive theaccoladesof the largest, longest

invertebrate(squid)andvertebrate(whale)animalsevertoliveonEarth.Tofindthelongestanimalintheworld,however,wemayhavetolookatanotherorderof cnidarians, the siphonophores, those jellyfish relatives that are formed fromconnectedindividuals,eachwithaspecializedfunctionlikefeeding,swimmingordefense.Withanoveralltentaclelengthofupto160feet(48.7m),thegiantsiphonophore(Prayadubia),whichresidesintheGulfStreamfromtheGulfofMexicotonorthwesternEurope,isadeservingcandidateforthetitle.

Acoastal-livingjellyfishintheSouthPacific,thePapuanjellyfish,orspottedjelly(Mastigiaspapua),feedsontinyzooplanktonandalgaecalledzooxanthellae.Itstranslucentbellisonetothreeinches(2.5–7.6cm)indiameter.Thespottedjellysometimesharborssmallfishinsidethisbell,

protectingthemfromlargerpredators.

Theworld’slargestjellyfish,thelion’smane(Cyaneacapillata)livesprimarilyinthecoldwatersoftheNorthAtlantic,theNorthPacificandtheArctic.In2010,theremainsofonelion’smanejellyfisharethoughttohavestung150peopleoffNewHampshire.Normally,thestingsarebrieflypainfulbutnotfatal.

Thelion’smanepreysonfish,zooplanktonandotherjellyfish.

Most jellyfish, including the lion’s mane, belong to the class Scyphozoa,whichcontains200knownspeciesresidentinallseas,fromthedeepopenoceanto coastal waters and from the poles to the equator. Themedusa of a typicalscyphozoan ranges from ¾ inch (2 cm) to 16 inches (40 cm) in diameter.Depending on the species, the medusa can vary in shape from a saucer to ahelmet.Thestrikingoranges,pinksandothercolorsglowingthroughtheslightlytintedbellare,infact,thegonads,stomachandotherinternalstructures.Solitarymedusaearebetterknownasthetruejellyfish.Somespecieshavefouroreightfrilly arms extending out from around the mouth opening; the arms carrystingingcellscalledcnidocytesthatassistinthecaptureandeatingofprey.Thearmsoftenlookthickerthanthetentacles.Thetentaclesaroundtheedgeofthebell can number anywhere from a handful to hundreds or even thousands. Insomespecies, thetentaclesareshortandlooklikeafringehangingdownfromthe base of the bell. In species such as the lion’s mane, the tentacles can beextraordinarilylongandcarrystingingcells.Other jellyfish in the scyphozoan class include the sea nettles that bother

swimmersalongtheNorthAtlanticshoreinlatesummer.InAustralianwaters,tropical seawasps andbox jellyfish, suchasFlecker’sbox jellyfish (Chironexfleckeri),cancauseseverelesionsanddeath,sometimesonlyafewminutesafterthe sting is inflicted. In oceanography and invertebrate zoology textbooks,photographsofgruesomelegwoundsfromjellyfishoftendisplaythehandiworkoftheseawasp.Sea wasp stings pack more punch than the feared Portuguese man-of-war

(Physalia physalis), a siphonophore that consists of a gas float and powerfulstingingtentaclesupto50feet(15m)long.Thegas-filledsacservesasasail,andifyoufindyourselfdownwind,itssteadyapproachseemsominous,althoughitcannotcontrolitsowndirection.Humans,fishandothermarineanimalsavoidthePortugueseman-of-war,whileseaturtleshuntandeatthem.The jellyfish that swim achieve locomotion by pulsating the bell using the

coronal muscles, a band of circular fibers on the bell’s underside. Severaltropicaljellyfishspeciesareactuallyrapidswimmers,primarilymovingupanddown thewater column.Nearly all painful or lethal jellyfish encounters occurwhenpeople or prey carelesslymove too close.Of course, jellyfishwith longtentaclesoccupyalargeareaandneednotdriftorpulsatefartoencounterfood.Mostjellyfishspeciesarecarnivorousordetritivorous,feedingonsuspended

foodparticles.Scyphozoansfeedonall typesofsmallanimals,butmanyseemtoprefercrustaceans.As the largestplankton,however, jellyfishchallengeourconventionalideasaboutcarnivores,foodpyramidsandplankton.Havejellyfishturned the tables? Some jellyfish seize and sting fish before devouring them.

Muchsmallerjellyfishandothercnidarianseatcopepodsandotherzooplankton.Even the smallest jellyfish can be formidable carnivores. Almost any sizeorganismthatapproachesordriftstooclosetojellyfishispreyedupon.Jellyfishconsumenotonlytheadultbutalsothelarvalstages.Someresearcherssuggestthat jellyfish may be outcompeting fish and other marine species that arefundamental to healthy food pyramids.Voracious, fierce competitors, jellyfisharetoughcustomers.Much is made of the dramatic metamorphosis of caterpillar into moth or

butterfly,butthecomplexmultistagetransformationofthescyphozoanjellyfishis worth pondering. Typical development goes like this: Jellyfish hatch fromeggs into free-swimming ciliated larvae, or planula, before turning into aplantlikeasexualpolypcolonythatoftenlivesontheseafloorbeforebranchingout, specializing into the various feeding and other polyps and acquiring thedrifter lifestyle. The reproductive polyp becomes the medusa, the typicaljellyfish shape, which is the sexual stage in the life cycle. Reproduction injellyfishcanbeaccomplishedsexuallyorthroughasexualbudding.As with many other animals with asexual reproduction modes, many

cnidarianshaveaphenomenalability toregenerate.Witness thehumblehydra.This simple jellyfish relative lives its whole life as a tube-shaped polyp. Theclassichydrastoryisthe1744experimentinwhichascientistpushedaknottedthreadthroughthebasaldiskandoutthemouthoftheanimal,turningthehydrawrongsideout.Itsoundslikeacruelexperiment,but it tookonlyashort timefor the gastrodermal and epidermal cells to move to their respective newpositions and regenerate the animal, good as new. Some cnidarians canregenerateanentireanimalfromgastrodermalorepidermalcells.AndthenthereisthecaseofthehydrozoanTurritopsisdohrnii,theso-called

immortal jellyfish.Whenitreachesitssexuallymaturesizeofnomorethan¼inch in diameter (5 mm), it resembles a tiny jellyfish. Yet when attacked orstressedenvironmentallyasitfloatsintropicalseas,thishydrozoancanreverttoa stalklike polyp, its physical form during an early stage of its development.Metamorphosis in reverse.And then it starts lifealloveragain. Itbecomes, ineffect,immortal.First described in 1996, the phenomenon of the immortal jellyfish has

receiveda lotofattentioninrecentyears.ItwasevenfeaturedonthecoveroftheNovember28,2012,editionofTheNewYorkTimesMagazine.Inaddition,research into hydra species that have only the polyp form and don’t producemedusassuggestthatthey,too,arepotentiallyimmortal.Researchersclashoverthepotentialimplicationsformedicineandextendinghumanlife,butafewarenow starting to explore this so-called transdifferentiation in other cnidarian

species,wherebyone typeofcell turns intoanother.Alas, immortalitydoesn’tmean invincibility: These extraordinarily resourceful cnidarians do die if theyare swallowedwhole, if thewater gets too cold or if they don’t have enoughfood.Butintherightconditions,thereisnostoppingthem,andresearchershavewatchedastheymigrateacrossoceans,carriedintheballastofships.Cnidarians are some of the most widespread and diverse organisms in the

ocean. Many cnidarians live in colonies comprising numerous units calledpolyps.Thecolonialcoralsareagoodexample.Othercnidarians,suchassomeof the colonial jellyfish, have polyps that are specialized for feeding,reproductionandothercolonytasks.Aringoftentaclessurroundsthemouthofeach fishing polyp, and a gut and nervous system connect all the polyps. Theexplosive cells in the tentacles called cnidocytes—unique to the cnidarianphylum—stingand immobilizepreyandallow jellyfish to snare copepods andotherzooplankton.Withthepolypssurroundingthecolony,ajellyfishbecomes,in effect, an enormous grid of armoredmouthswaiting for the next unwittingpasserby.Thereissomethingtobesaidforalifestrategyofwaitingaround,relyingon

one’s prey to make mistakes and, in general, conserving energy. It certainlyworks for jellyfish and other cnidarians. In disturbed ecosystems, however,jellyfishdon’twaitaround,theytakeover.Thisisofconcerninviewofglobalwarming,themeltingaroundthepolaricecaps,theacidificationofthesea,theoverfishing of commercial fish and the multiple impacts these stressors arecurrently having and will continue to have on the ocean. As ecosystems losetheir integrity and resilience, the increasing number and extent of jellyfishblooms already characterize someparts of the oceans. Such ocean ecosystemsmaylosethetraditionaltoppredators,suchassharksandkillerwhales,onlytobereplacedbyjellyfish.Justasthedominantantsandcockroachesmayonedayinherit theEarth, jellyfishandsomeof their immortal relativesmayeventuallydominatetheocean.

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ThePortugueseman-of-war(Physaliaphysalis)isaninvertebratecarnivorecalledasiphonophore,acolonialanimalrelatedtojellyfish.WhileoceanswimmersfearthePortugueseman-of-war,turtlesreadilyeatit.

The flower hat jellyfish (Olindias formosa) spends most of its time trying todazzleandensnaresmallfishneartheseaflooroffthecoastsofBrazil,ArgentinaandsouthernJapan.Itstentaclesproduceastingthatisdeadlytosmallfishandpainful,thoughnotlife-threatening,tohumans.Itcanreachadiameterofuptosixinches(15cm).

Anas-yet-unnamedtransparentscyphozoanjellyfishintheMediterraneanrevealsitsbioluminescence.

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BigSharks1ThePlankton-Strainers

IKE THE LARGEST whales, the largest fish in the world are notdangerous predator carnivores. They are plankton-strainers andplankton-eaters: the basking, whale and megamouth sharks. These

sharks swim steadily through the water, mouths open, engulfing a soup ofassortedcopepods,krillandotherzooplankton.Moresea-monsterstoriescomefromthisgroupofanimalsthanfrommostotherquarters,withtheexceptionofcarnivoroussharksandthegiantsquid.Earlymarinerscanperhapsbeforgivenfor mistaking plankton-eating sharks for sea monsters; their sheer size, theiropen-mouthed swimming posture and their occasional “ferocity” whenharpooned—draggingaboatunderwater,forinstance,orsmashingitinaneffortto escape—are formidable traits. Add to this the tendency for dead sharks(particularlybaskingsharks),perhapspartiallyeatenbycarnivoroussharksandbatteredbywaves,tobreakintoratherlarge,monstrouspieces.One of the great, long-running 19th-century monster stories describes just

suchademi-beastfromtheOrkneyIslandsnorthofScotland,initiallythoughttobe a 55-foot-long (17 m) sea snake with a horse’s mane and six legs. Thescientific paper published in 1811 created a new genus and species for this“seawater snake,” but scientists continued to argue about the monster’s trueidentity. Only 122 years later, in 1933, did a paper published by the RoyalScottishMuseum (now theNationalMuseum of Scotland) throw out the newspecies by showing that the monster was a decomposed basking shark. The“mane” of shark fin fibers, the extra “legs” of the shark’s claspers and theskeletalremainsofthevertebralcentrumwerethoseofabaskingshark.Infact,the animal must have broken into two pieces: one, the piece that was found,contained the cranium and backbone; the other contained the jaws, gill archesandflippers.

Showingoffthetypicalfeedingpostureforitsspecies,abaskingshark(Cetorhinusmaximus)swimswithitsmouthwideopen,tryingtoengulfasmuchplanktonasitcantosupportitsbulkyframe.At33feet(10m)ormoreinlength,thebaskingsharkisthesecondlargestfishspeciesintheworld.

The slow-swimmingwhale shark (Rhincodon typus), theworld’s largest livingfish,reacheslengthsofuptoareported46feet(14m).Likebaleenwhales,thewhale shark filter-feeds on small fish, krill and other plankton.Often, amini-ecosystemconsistingofvariousfish,suchasthesepilotfish(Naucratesductor),travelswithit,eatingtheshark’sleftoversandcleaningupsurfaceparasites.

Comingface-to-facewithamegamouthshark(Megachasmapelagios)isarareoccurrence.Thisclose-upwastakeninthewatersoffCalifornia.Atupto17feet(5m)long,themegamouthisthesmallestofthethreefilter-feedingplanktivoroussharks.Behinditsblubberylips,ithidesnumeroustinyteeth.

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DancingwithSquid

O GLIMPSE To glimpse a huge group of squid jetting effortlesslythroughthewater, those largeeyesneverwavering, theirappendagesin fluid motion behind them, is to admire nature’s poetry of

movement. The high-strung squid respond to changes in the underwaterchoreographywithlightning-quickspeed.Atdepth,inthedarkness,thedancersusecomplexsignal lights that flashandbeaminvariouscolorsandpatterns toblind,mystifyandentrance theiraudience.Afewspeciesalsoemploytheir jetpropulsion to shoot out of thewater likePeterPan in an ambitiousBroadwaystageadaptation.For squid residing in themiddle levels of the foodpyramid, the “audience”

includes both predators and prey. In the open ocean, from shallow to deepwaters, young fast-growing squid provide a key link in the food pyramidbetween copepods, krill and other zooplankton and the top-predator fish andmarinemammals.Squidcomeinmanysizes,shapesandspecies.Sometravelingroups; others are strictly solo acts. At least 181 squid species have beenidentified in 25 families that make up the order Teuthoidea, although thesystematicsisfarfromcomplete,andtherearealmostcertainlynewspeciesstilltobefoundorsortedoutfromwhatamountstoataxonomictangle.Theyrangeinsizefromlessthananinch(2.5cm)inlengthtomorethan50feet(15m).The squid body is amarvelous, odd design that somehowworks. Squid are

mollusks,buttheyarenothinglikeclamsormussels.Infact,theshellislocatedinsidethebodyinareducedfragmentaryformknownasthepen.Theshellhasatrophiedinfavorofotherfeaturesofthebizarresquidanatomy.Justlookatasquidnexttoanoctopus.Bycomparison,anoctopusissimple:a

headwitheightarmsattached.Onasquid, it’snotsoeasytotellwhichendiswhich. Swimming through the water, a squid doesn’t give the game away,because it can jet forward or backward. So which way is forward and whichbackward?Thesquidappearstohaveatailortailappendagesateitherend.In

fact, the10 appendages—eight thickoctopuslike arms and two thinner, longersucker-laden tentacles for catching prey—grow out of the head. At thehydrodynamically shaped rear end of the animal, called the mantle, two finsundulateupanddown,providingsomepropulsionincertainsquid.Themainjetpropulsion, however, is producedwhen the squid drawswater into itsmantlecavity, thenexpels itunderpressure through the siphon,which it can rotate tochangedirection.Therapidandconstantmovementofwaterthroughtheanimalalsoprovidesthecrucialsourceofoxygen;gillsinsidethemantlecavityextractoxygenfromthewater.Squidhavebeen called “invertebrate athletes” and “Olympian cephalopods”

bysquidresearchersRonO’DorandR.E.ShadwickofDalhousieUniversityinHalifax,NovaScotia.Theirviewis that jetpropulsion isan inefficientwayofgetting around which forced squid to become extremely athletic, employinghigh-poweroutputsandrapidoxygenconsumptiontoachievespeedburststhatcan exceed those of the fastest fish. But squid are also marathoners, able tocompletemigrationsovermanyhundredsofmiles.Besides the unusual body plan, a big part of the squid’s success lies in its

excellenteyesight, itsbrainandthehighpercentageofbodyweightdevotedtoitsnervoussystem.First,theeyesight.Therodsandconesintheretinasuggestthe ability to obtain detailed images that may include color. As the squidapproaches theneardarknessatdepth, itspupilsexpanddramatically to fill itslargeeyes.Butextraocularphotoreceptors,roughlycomparabletothosefoundininsects and spiders,may allow some squid to sense overall light levels in thewater,perhapspartlyasawaytofine-tunetheirownbioluminescence.Comparedwiththebrainsoffishandmostotherinvertebrates,thesquidbrain

islargeandcomplex.Itisliterallyamassofnervegangliasituatedbetweentheeyesandallaroundtheesophagus.Nowonderasquidmaceratessothoroughly—itsfoodmustpassthroughitsbrain!The squid’s secret sourceofpower,however, is that it possesses the largest

nerve axons, or fibers, of any animal—a single axon is about 100 times thediameterofahumannervefiber.Thishasmadethesquidalongtimefavoriteforscientistsstudyingnervoussystems.

Superbeyesight,acomplexbrainandasupercomputernervoussystemwithfiber-optic-likeaxonsactaspotenttoolsthat,together,givethesquidlightningreflexes,enablingittoreacttoastimulusandsendmessagesto

enablingittoreacttoastimulusandsendmessagestothemusclesfasterthaninanyotherknowngroupof

animals.

Namedforitshugebugeyes,aglasssquid(Teuthoweniamegalops)jetsalongtheMid-AtlanticRidgeatdepthsof3,300feet(1,000m)andmore.Itstransparentbodyiscoveredinchromatophores,whichallowittochangecolor.Threephotophoresaroundeacheyeproducelightforseeingorsignalinginthe

darkdepths.

A close-up of a deep-sea squid (Histioteuthis sp.) shows themain part of thebody,calledthemantle,whichcontainsthesquid’svitalorgans.Visibleontheunderside of the body is a multipurpose funnel through which the squid canpump in and squirt outwater to propel itself through the sea. It also uses the

funneltoexhale,squirtink,expelwasteand,inthecaseofthefemale,layeggs.

The five-inch (13 cm) mesopelagic squid (Octopoteuthis deletron) offers upsperm packets indiscriminately to both females and males. After examiningcapturedsquid,researcherswereinitiallypuzzledwhentheyfoundthesepacketsonmalesandassumedthatself-implantationhadtakenplace.Butdetectingthesexof its fellowsquid isdifficult in thedarkwaters inwhich itdwells, so themaleO.deletronstrategicallyplaysthenumbersgame.(Image©MBARI)

Agiantsquid(Architeuthisdux)iswasheduponabeachinTasmania,Australia.Untilrecently,giantsquidencounterswerelimitedtostrandingssuchasthisone,witnessedbyBritishTVwildlife-documentarypresenterNigelMarven.

Superbeyesight, acomplexbrainanda supercomputernervous systemwithfiber-optic-likeaxonsactaspotenttoolsthat, together,givethesquidlightningreflexes, enabling it to react to a stimulus and send messages to the musclesfaster than in anyotherknowngroupof animals.This abilityhelps inhuntingand inmakingquickgetaways toavoidpredators.Thephotophores—the light-producingorgansandchromatophores,orcoloredcells,foundtovariousextentsin squid species—allow the squid to change its appearance faster than achameleon and with more varied patterns. Some squid are able to producestripes,spotsandbumpsorcanaltertheircolorentirelyforcamouflageorstartleeffect, or if they continue transforming rapidly, they can create confusion andescapefromapredator.Becausethechromatophorechangesarevisibleonlyintheuppereuphoticlayers,photophorestakeoverinthedarkmid-todeepwaters.Theselightshowsmayalsofunctionascommunicationsignalsinmatingritualsandwhoknowswhatelseinthestillmysteriousyetdazzlingworldofsquid.In the temperate North Atlantic, the common short-finned squid (Illex

illecebrosus)growstomaturity,breedsanddiesallwithinayear.Inearlyspring,theyoungsquid’smainjobistofinddensepatchesofzooplankton.ByMay,itmoves into thecoastalwatersofNewEnglandandeasternCanada tohunt forschooling fish, such as herring and capelin. It soon reachesmature size at 12inches(30cm)longformales,notincludingthetentacles;14inches(35cm)forfemales.Bylateautumn,afteragoodsummerandafullbelly,itreturnstodeepwatersneartheedgeoftheshelf tofindamate,breedanddie.Formostsquidspecies,theruleislivefastanddieyoung.ResearchersfromMontereyBayAquariumResearchInstitutehavebegun to

unravelthehastysexlifeofafive-inch-long(13cm)Pacificmesopelagicsquid(Octopoteuthis deletron) that has bioluminescent arm tips. This squid uses itspenistoattachthespermatophorepouch,whichcontainsmillionsofsperm,ontothebodyofafemale.Thepouchthendischargessacscalledspermatangia,whichimplantinthefemale’sbodybutremainvisible.However,HendrikHovingandhiscolleagueshavefoundthesesacsarepresentinequalnumbersonthebodiesofbothfemaleandmalesquid.Sowhat’shappeninghere?Withsomesquidspeciesthathavebeencaughtinnets,scientistsbelieveself-

implantationmayhavetakenplace.ButinthecaseofO.deletron,itisclearthatmalesareimplantingothermales.That theratioisequalrevealsindiscriminateimplantationattempts.Withitsbiologicalclocktickingfasterthanatimebomb,thissquidsimplyhasnotimetowastewithcourtshiporotherpreliminaries.AssciencewriterEdYongputit:“Bettertoejaculateoneveryoneandaskquestionslater.”Invariouspartsof theworldocean,squidnotonly“dotheirownthing”but

also fulfill ecological roles that form some of the building blocks in foodpyramids.Nomatter theirsize,manyof thesquid,evenshort-finnedandothercommonsquid,haveaslightlymonstrousappearanceanddemeanoraboutthem.To paraphraseAmerican naturalist Aldo Leopold, 10 limblike appendages aremore than twice toomany from thehumanpointofview, fouror fewerbeingclearlyinfavor.Imagine10snakelikelimbscurlingaroundyourbody,probing,ensnaringandthengraspingyouwithsuckersringedwithteeththatlatchonforgood. Yet, as with many groups of organisms, the truly unusual arises whenspeciesdivergeandevolvealongnewpathwaystofit,fillandsometimesshapeevermorearcaneandbizarreniches.Soaretruemonstersborn.Consider the giant squid.Only in the first decade of the 21st centurywere

scientistswhowerestudyingthegiantsquidabletoglimpsealivingindividualforthefirsttime.Becausethegiantsquidhasyettobethesubjectoflong-termstudiesinitsnaturalhabitat,muchofwhatcanbesaidorconjecturedaboutthisgargantuan creature is based on limited data and on extrapolation from ourknowledgeofsmallersquid.Afewmythsaboutthegiantsquidarefallingintodisfavor,butmostoftheuncertaintyaboutthenatureofthebeastremainsverymuch intact.Taxonomistshaveyet to advancevery far inpiecing together theevolutionary history of squid from looking at the entire order. But a casual,defensible hypothesis for the giant squid’s evolutionmightwell go somethinglike this: Small to modest-sized squid occasionally produce larger and everfaster-growingoffspringthatfindsomeadvantagesandahomeindeeperwaters.Overmanygenerations, the animalgetsbigger andbigger, growing faster andfasterandlivingdeeperanddeeper.Itisnotjustageographicalniche—itisthesizeandtheabilitytoachievesize

rapidly,aswellasthedepth.Animalsaremostvulnerabletobeingeatenwhensmall or, for larger squid, when young. Rapid maturation thus avoids aprotractedperiodof vulnerability to predation.Moving to a deeper part of thesea means fewer predators are around. Approaching full size at roughly thelength of a large mature whale leaves even fewer predators to fear—just thelargestcarnivoroussharksandthespermwhale,thelargestofalltoothedwhales.Notmuch else bothers the giant squid—except perhaps other giant squid.Thefew studies of stomachs from recovered giant squid carcasses document theremainsof10fishspecies,clams,tunicates,crustaceansandfivesquidspecies,includingthegiantsquid.There’sanuntoldstoryhere.Aregiantsquidroutinecannibals,highlyterritorialorjustmessyeaters?Nooneknows.Themaintoolsofthegiantsquidareitstentacles,whicharelikeanenormous

pair of bungee cords.Theoversized extendable appendages stretch far beyondthe squid’s impressively long eight arms and are partly responsible for the

widelyvaryingestimatesofmaximumsize.Basedonmeasurementstakenofalimitednumberofrecoveredanimals,thetentacleshaverangedanywherefrom40 to 60 feet (12–18m). The sucker-covered club at the end portion of eachtentacleisagiantsquidspecialtyandisusedforgrasping.Thetentaclesandthearmsallhavesuckers:tworowsonthearms,fouronthetentacles.Eachsuckeris like a suction cup ringed with sharp, toothlike protrusions made of chitin.Theselethalsuckersareresponsibleforthescarsfoundonspermwhales.The giant squid is unique among cephalopods in that it can “zip” its long

tentaclestogetherusingaseriesofsmallsuckersandmatchingknobsalongtheirlength. The result is a single extremely elastic shaft with two heavy clawlikeclubs at the end—as impressive as a medieval weapon. Even so, no one haswitnessedagiantsquidhuntingbigprey,letaloneobservedhowthesquidusessuchaweaponofdestruction.Someresearchersmaintainthatthegiantsquidissluggishcomparedwithothersquidspeciesandthat its tentaclesmaynotevenbeusedinhunting.Yetthegiantsquidappearstohavethecapabilityofcomingatitspreywithswinging,bone-crushingmomentum.Judging from size alone, the ultimate predator-prey battle in the seawould

seem tobebetween thegiant squid and the spermwhale.But howmuchof abattle would it be? The sperm whale is a squid specialist. Its huge, graspingteeth, deep-diving skills, sonic abilities, large brain and sheer size are allextraordinary adaptations seemingly designed to catch, subdue and eat giantsquid,despitethesquid’sownbrandofintelligence,nottomentionitsabilitytojetawayinaninstantortowielditsgrapplingarmsandtwolethaltentacles,bothequippedwithsuckers,ifitstandstofight.One theory from a dedicated squid supporter suggested that the giant squid

might be able to subdue a sperm whale by holding its jaws closed or evendrowningit,butthatscenarioisfar-fetched.Six-inch-long(15cm)squidbeaksin sperm whale stomachs prove that sperm whales often “win,” while suckermarks on the bodies of sperm whales hint that squid fight back fiercely.However,at leastonegiant squidexpert,FrederickAldrich,conjectured thataspermwhalewouldneverloseabattlewithagiantsquid.Buthowoftenwouldthewhalemanagetosubduethesquidanddevourmorethanatentacleortwo?Smithsonian zoologist emeritus and giant squid authority Clyde Roper and

others have examined sperm whale stomachs and estimated that one spermwhalecouldeat40,000squidinaweek.WhensciencewriterWendyWilliamswas conducting research for her book Kraken: The Curious, Exciting, andSlightlyDisturbingScienceofSquid,Ropertoldherthatbasedonhowoftenthebeaksof giant squid appear in the stomachsof spermwhales, hewouldguessthataspermwhalemighteatoneortwogiantsquidperweek.Thatmakes50to

100giantsquidperyearperwhale.Giventhattherearehundredsofthousandsofspermwhalesintheoceansoftheworld,thiswouldsuggestthattherearealsolargenumbersofgiantsquidjettingaroundinthedeepocean.For all its evolution toward greater size, the giant squid may well have

compromisedspeed. Itsbodyappears tobesoftandspongyandsusceptible toscarring. Some scientists have speculated that the giant squid may even be aretiringcreature.Thustheanimal thatauthorRichardEllis(TheSearchfor theGiantSquid)declaredis“theonlylivinganimalforwhichthetermseamonsteristrulyapplicable...[whichis]responsibleformoremyths,fables,fantasiesandfictions than all other marine monsters combined,” may turn out to be nomonsteratall,exceptinthesenseoftheill-advisedproportionsofitsbody.Likeaninsectscaledupto thesizeofadinosaur(an impossiblecreature), thegiantsquidstretchesthelimitsofcredulity.Itwillrequirepainstakingobservationandmore study to confirm all this, and it may take more than the NationalGeographicSociety, theDiscoveryChannelandNHK(theJapanBroadcastingCorporation)spendingmillionsofdollarstofinancemultipleexpeditionstotryto photograph thismythic creature of the deep in its natural habitat. The realjackpotwillbetorecord,forthefirsttime,anencounterbetweenaspermwhaleandagiantsquid.Howmanymoreyearswillittaketoachievethat?The1997NationalGeographicexpeditiontoKaikouraCanyon,NewZealand,

failed to find a giant squid. But it did capture a rare, deep-sea predator-preysceneondigitalvideo:atwo-foot-long(60cm)arrowsquidbattlingathree-foot(1 m) spiny dogfish shark at 2,400 feet (730 m). This provided a tantalizingglimpse into the deep—a living squid unfurling its magnificent tentacles toencircleabitingsharkinanattempttosubdueit.Thetwohungryanimalsfoughttoadraw,andthesharkretreated.Theimagewasallthemorestrikingbecauseof thecolorless, raw,grainyquality inapublicationnoted for its sharp, color-balancedpictures.Thephotographillustrateswhythedeepseaandknowledgeofthebehaviorofitsresidentsremaintrulyremote.After a final attempt in theKaikouraCanyon in 1999,NationalGeographic

turned to other projects. Apparently, it was going to take a lot more time,perhaps another method, another location and an even bigger bankroll todocumentthisanimalonfilm.Two scientists willing to invest their time and try new approaches were

TsunemiKuboderafromTokyo’sNationalMuseumofNatureandScienceandKyoichiMorioftheOgasawaraWhaleWatchingAssociationintheOgasawara,orBonin,Islands,620miles(1,000km)southofTokyo.Theislandsareknowntobeaspermwhalehotspot.Mori, thefirstscientist tousephoto-IDtostudywhales in Japan, had lived in the islands for years. Kubodera was lured to

Ogasawarabecausethespermwhaleshere,asinotherlocations,arethoughttofeedongiantsquidregularly.Giantsquidremainshadbeenfoundfloatingatthesurface, and longline fishermen had pulled up pieces of tentacles on baitedlures.Undiminishedafterthe25-hourocean-goingferryfromTokyotoOgasawara,

Kuboderawasdeterminedtofindawaytophotographandfilmthegiantsquidin action. He met with Mori, who had access to the whales and boats, hadexperience on the sea and knew the islands well. It seemed like a scientificmarriagemeanttohappen:apartnershipbetweenaworldsquidauthorityandaworldspermwhaleauthority.Butitwasmorethanthat.KuboderaandMoriaretwohumble,low-keyresearcherswho,althoughtheyenjoyedlittleinthewayofabudget,eachpossesspatienceandperseverance.(WhenIencounteredMoriata fewconferences in theearly2000s, Iaskedhimabouthiscurrentworkwithspermwhales.Herepliedthathewasdoingsomeresearchonsquid.Hedidn’tsay“giant,”andhedidn’tusetheterm“fieldwork.”Ididn’tthinktwice.Inmyexperience,itwasnotunusualthataspermwhalebiologistwoulddoresearchonsquid.)Working from their research boat in 2002, Kubodera and Mori began

dropping baited vertical lines in the regionwhere spermwhales are known tohunt, along the 4,000-foot (1,200 m) contour, six to nine miles (10–15 km)southeast of Chichi-jima, the main island in the Ogasawara Archipelago.Occasionally, they went into waters half that deep for nighttime attempts, asspermwhalesareknowntofeedatshallowerdepthsatnight.Thefieldseasonforspermwhales isSeptember toDecember.Between2002and2004, theduomadeatotalof23deployments.The method Kubodera and Mori used was partly established fishing

technology and partly high-techmodern biology. They hung up to 3,300 feet(1,000m)oflinefromthreelargefloats.Aninstrumentpackageattheendofthelinecarriedadigitalcamera,atimer,astrobe,adepthsensor,adataloggerandaswitchactivated togooffwhenthepackagewasbelow650feet(198m).Baitrigshanging10feet(3m)belowthepackagewereweighteddownbyatriple-hooked lead squid jig baitedwith a fresh Japanese common squid. Two shortsidebranchescarriedasinglelargehookbaitedwithanothercommonsquidandameshbagfilledwithmashedeuphausiidshrimpasanodorlure.Thecamera,whichwasaimeddown toward thebait,was set tocapture150-kilobyte JPEGimagesevery30secondsforfourtofivehours.At9:15a.m.onSeptember30,2004,asKuboderaandMoriwouldlaterreport

in theProceedings of the Royal Society B: Biological Sciences, an individualgiantsquidattackedthelowersquidbaitofoneoftheirdeployments,atadepth

ofnearly3,000 feet (900m)overa seafloordepthofalmost4,000 feet (1,200m). The camera snapped a photo as the two long tentacles wrapped in a ballaround thebait—revealing the species’ attack and feedingposture for the firsttime. Right away, the club of one of the giant squid’s long tentacles becamesnaggedonthesquidjig.Theimage,welllitthoughgrainy,wastheworld’sfirstphotographofalivinggiantsquid.Over the next four hours, the camera took some 550 JPEGs, recording the

squid’sstruggletodetachitselffromthejig,asitattemptedtoswimorjetaway.Forthefirst20minutes,thesquidtriedtopullaway,disappearingfromcameraview. Then, formore than an hour, the squid repeatedly approached the line,spreading its eight armswidely around it.At onepoint, the squiddragged thelineupfromadepthof3,000feet(900m)toonly2,000feet(610m).Four hours and 13 minutes after the giant squid had become snagged, its

tentaclebrokeoff,assignaledbythesuddenslacknessofthelineinthecameraframe. The severed tentacle remained attached to the line and was retrievedwhenKuboderaandMoripulledupthecamerasystem.Evenbeforetheyviewedthe images, theyknewtheyhadsomethingbig.The tentaclewasunmistakablythatofagiantsquid,exhibitingthecharacteristicpairedsuckersandlugsalongthe tentacle shaft.Most surprisingofall, the recovered sectionof tentaclewasstillmoving.KuboderaandMoriwatchedinamazementasthelargesuckersofthetentacleclubrepeatedlygrippedtheboatdeckandeventheirfingers,whentheydaredtoofferthem.LaterDNAanalysisprovidedfurtherproofthatitwas,indeed,agiantsquid.

Thetentaclewas18feet(5.5m)long,allowingtheresearcherstoestablishthesize of the animal.Assuming the tentaclewas severed at the base, the animalwasabout26feet(8m).Itwasnotanywhereneartherecordsizeof40feet(12m)and610pounds(277kg),butitwasbig,anditwasalive.“Considerableeffortstoviewthiselusivecreatureinitsdeep-seahabitathave

been singularly unsuccessful,” reported Kubodera and Mori in their journalarticle,withroomforunderstatement.“Hereweshowthefirstwildimagesofagiantsquidinitsnaturalenvironment.”Most exciting of all, they now had some insights into the character and

behaviorofthisspecies.Manyresearchershaveconsideredthegiantsquidtobesluggish at best—a neutrally buoyant squid. However, wrote Kubodera andMori,“ourimagessuggestthatgiantsquidsaremuchmoreactivepredatorsthanpreviously suggested ... using [their] elongate feeding tentacles to strike andtangleprey.”IwasinPatagoniainSeptember2005thedaythisstoryhitthefrontpageof

The New York Times and of a few hundred of the world’s other major

newspapers.Severalmonthslater,IwaspresentingwithMoriataconferenceinOgasawara, where he and Kubodera had photographed the giant squid. Heshowedme theprizedsevered tentacle, stored ina freezer, and told stories farintothenight,playingthelongversionoftheNHKfilmthathadbeenmadeontheir work, along with a running commentary and juicy digressions. WhileNationalGeographicandotherinstitutionshadspentmillionsofdollarstryingtofind and photograph the giant squid without success, these two Japanesescientistshadcleverlyandquietlymanageditonbeermoney.As for the severed tentacle, some squid species can regrow a tentacle. The

giantsquidisthoughttobeoneofthem.Manyoctopusandsomesquidspeciescan also regrow arms. Monterey Bay Aquarium Research Institute researcherStephanie Bush became curious when she found that 25 percent of themesopelagicOctopoteuthis deletron squid she observed had at least one armwiththetipbrokenoff.Whenshebroughtlivespecimensintoherlab,shesawindividualsbreakingoffanywherefromtwotoalleightoftheirarms,usuallybygrabbingontosomethingorbyhavingsomethinggrabthearm,creatingtensionthat would cause the arm to snap off. The breaks occurred in various placesalongthearm.AsBushwatchedthebrokentipsflailingaboutformorethan10seconds, eachonebrightlyglowing from the light-producingorgans at the tip,shedetermined that these flagrantactsof self-mutilationmustbeacaseof thesquidshedding itsbioluminescentarmtips toconfuseanddistractpredatorsorprey.This behavior has been seen in other squid species, such as the vampiresquid,notedearlier.Because thesquidusually losesonly the tipof itsarm, itsabilitytohuntandeatisnotcompromised.Continuing his work on giant squid in Ogasawara, Kubodera managed to

capturethefirstvideoevidenceofalivegiantsquidinDecember2006.Havingbeen caught on a vertical longline, the squid languished at the surface. Ajuvenilefemaleabout11feet(3.5m)long,includingthetentacles,thesquidwasclearlyoutofitselementinthewarmsurfacewaters.Agiantsquidatthesurfaceof thesea is likeadeep-divingspermwhale inshallowwaterorstrandedonabeach—inserioustrouble.AsnewsspreadaboutthissecondsuccessinOgasawara,othermembersofthe

media and scientific community began to think about capturing high-qualityvideo that would offer new and more detailed insights into the life of thismysterious creature. NHK had been with Kubodera from the beginning andsimply continued the partnership, and they were joined by the DiscoveryChannel,whichwaslikewiseeagertogetsubstantialvideoofthegiantsquidinitsnaturalhabitat.

Feedingonwhatappearstobepartofalargesquid,possiblyagiantsquid,amalespermwhale(Physetermacrocephalus)surfacesoffthePacificcoastofMexico.

OnSeptember30,2004,JapanesescientistsTsunemiKuboderaandKyoichiMoritookthefirstphotographofalivinggiantsquid(Architeuthisdux)initsnaturalhabitat—agrainyglimpseofthelegendary“seamonster”inaction.

Aftermuchdiscussionandafewshow-and-tellworkshopsandpresentations,thegroupdecidedthatinordertobesuccessful,thenextexpeditionwouldhavetoemployamultiprongedapproach.Kuboderahadtobethere,ofcourse,givenhiscleverworkwithMoriandhissuccesstodate.Asalways,hisrolewouldbeunobtrusive; like any fisherman, he would quietly put out the bait, then sitpatientlyandwait.SteveO’Shea,aNewZealandsquidresearcherwhohadrecoveredanumber

of giant squid carcasses aroundNewZealand, thought that squid pheromonesandotherattractingchemicalswouldbetheanswer.Then there was the expedition’s wild card: bioluminescence specialist Edie

Widder, who brought her deep understanding of the language of light in themesopelagic. Widder would try to engage the animals through her electronicjellyfish,anoptical lurewithprogrammableblueLEDsthatshehaddevelopedtoattractbioluminescentanimals.Could itworkwith the giant squid?Although not bioluminescent itself, the

giantsquidhasthelargesteyesintheanimalkingdom,evenlargerthantheeyesofwhales.Aboutthesizeofaflattenedbasketball,eacheyehasadarkirisandanadjustablelens.Sucheyeswouldnotmissmuch.Surely,whenhunting,theywereonthelookoutfortheflashinglightsofsuspectedprey.Itwasworthatry.Totaketheworkongiantsquidtothenextlevel,however,theteamdecidedit

wouldhave tomeet thebeast inasubmarine,attract it, spend timewith itandthenfilmit inhighdefinition.Thatwasthechallenge.Itwasgoingtotakethescientists faroutof theirownbudgetarycomfort zones,given thehighcostofmounting such an expedition in Japanese waters. To have even a chance atsuccess,theywouldhavetoworkasalargelyself-containedunitforanextendedperiod,weeksonend.Itwasaboutthenthatabenefactorwithanappetiteforadventureandawish

tousehiswealthforscienceandconservationcameintothepicture.Aself-madeAmerican billionaire, Ray Dalio is a hedge-fund manager and the founder ofBridgewater Associates. Dalio launched the company in 1975 from his smallapartment on East 64th Street in New York City, and according to Forbesmagazine,heturneditinto“theworld’sbiggesthedge-fundfirm.”In2011,DaliopurchasedtheAlucia,a185-foot(56m)motoryachtequipped

withsensors,cranes,itsown$2million(U.S.)Tritonsubmarineandasubmarinelaunchpad. Although Dalio had bought the yacht for underwater familyexcursions,heofferedtheAluciaandthethree-personsubtotheresearchteamand NHK-Discovery Channel. His grand gesture made possible a hugecontributiontoscienceandtogeneratingpublicsympathyfortheseanimalsandtheirdark,deep-seaworld.

On June 22, 2012, the research and camera teams boarded the Alucia atSagamiBay,mainland Japan, andheaded forOgasawara forwhatwouldbe asecretsix-weekresearchcruiseinsearchof thegiantsquid.BesidesKubodera,O’Shea andWidder, Patrick Lahey, the president of Triton Submarines LLC,wasonboardtotrainthecrewtorunthesub.OnceinOgasawara,thesubtripswere set up around the clock, each one lasting from 8 to 10 hours. Despiteoccasional rough seas and other complications, the teammanaged tomake 55dives,spendingnearly300hoursunderwaterandoftentakingthesubdowntoitsmaximumdepthof3,300feet(1,000m).In addition to the pilot, a scientist and a photographerwere on the sub for

every dive. On his dives, O’Shea brought along a potent essence of squid—chemicals he had obtained from the gonads, arms and mantles of strandedmature male and female squid. He was hoping that these sexual pheromoneswouldlureadultsquidtoinspectthesource.O’Sheawasnotconcernedthatthenoisemadebythesuboritslightswoulddeterthesquid.Infact,hethoughtthebest approachwould feature“lightsblazing, singingNeilDiamond,makingasmuchnoiseaspossible,squirtingallsortsofchemicals into thewater. I firmlybelieve that these squid don’t give a damn about light or sound, and the onlythinggoingthroughthat20-grambrainiseatingandbreeding.”O’Shea’sdivesyieldednumeroussightingsofcreaturesattractednotonly to

thebaitbuttothesubitself.Ona1,640-foot(500m)dive,asfreelancejournalistArikiaMillikandescribedinherJanuary25,2013,blog,“theyoncefeltathumpfrombelowandfoundthemselvesshroudedinamassiveinkcloud.O’Sheasawmoresquidthananyoneelseduringhisdiveswiththelightson,butnonewereofthegiantvariety.”EdieWidderwas also happy to leave the lights on, but her lights of choice

were theblue flashing lightsof theelectronic jellyfish she’dnicknamed thee-jelly, which was programmed to imitate the panicked behavior of a commondeep-sea crown jellyfish such as the Atolla when it is attacked.When undersiege, the Atolla jellyfish (Atolla wyvillei) produces a bioluminescent displayvisible tootherdeep-seacreatures,andalthough this jellyfish isapparentlynoton the squid’smenu,Widder knew from earlier experiments that small squidcouldbeattractedtothee-jelly.AsWidderput it atapost-expeditionTEDtalk,abioluminescent jellyfish’s

“onlyhopeforescapemaybetoattracttheattentionofalargerpredatorthatwillattackitsattackerandtherebyafforditanopportunityforescape.It’sascreamforhelp, a last-ditch attempt for escapeanda common formofdefense in thedeep sea.” Widder’s hope? That the e-jelly’s “bioluminescent burglar alarm”wouldattracttheattentionofagiantsquid.

Widderhadworkedwithdeep-divingremotelyoperatedvehicles(ROVs)anddeep-seasubmersiblesbeforebuthadfoundthehydraulicsandelectricthrustersto be too noisy. Shewanted tomake sure the squidwouldn’t be distracted orfrightened away by unnecessary sounds, so rather than deploying the e-jellyfromthesub,Widderattachedittoacameraplatformdesignedtobetossedintotheoceanfromtheship.Theplatform,namedMedusa,wasconnectedtoafloatandmore than 2,000 feet (610m) of line. After sinking into the deep sea, itsilently emitted only the red light that is invisible to most deep-sea animals.There,thecamerawaslefttodoitswork.Widder’sapproachwassuccessful.Afteroneof thedeployments,shepulled

uptreasure:thefirstbitofvideoofalivegiantsquidattractedbythevenerablee-jellyandcapturedinactionbytheremotecamera.Hereyeslitupassherememberedthemoment:“Itwasasifitwasteasingus,

doingakindoffandance—nowyouseeme,nowyoudon’t—andwehadfoursuch teasingappearances.Then,on the fifth, it came inand totallywowedus.Whatreallywowedmewasthewayitcameupoverthee-jellyandattackedtheenormousthingnexttoit—theplatform—whichIthinkitmistookforapredatoronthee-jelly.”Forthedurationoftheexpedition,Widderfailedtoseeanygiantsquidfrom

thesubmersible,butinall,shecapturedsixvideosnippetsofgiantsquidviaherremotesystem.Dogiantsquidpreferthelightsonoroff?Itappearsthattheylikedtheblue

lightsanddidn’tmindtheinfraredlightsfromthecamerasystem.Andthequietapproachhadn’tkeptthemaway.Kubodera, in his approaches in the sub, also employed the infrared-lighting

system, and he adopted the quietest approach—the opposite of guns-ablazingO’Shea.Hethoughtthegiantsquidmightbesensitivetosoundvibrations.Asidefrom the lighting system, he switched off everything in the sub that waselectronic,eventhetemperature-controlsystem.Everthefisherman,hebaitedathree-foot-long (1 m) diamondback squid to a squid jig of the type used inlonglinefishing.Healsoattachedalighttothesquidbait—adoubleattraction—andsuspendeditinfrontofthesub.Thenheandthesub’scamerasfocusedontheilluminatedbaitandwaitedandwaited.Foreighthoursatatime,Kuboderastudiedthebaitintheredlightandspoke,onlywhennecessary,inawhisper.Finally,agiantsquidswamintosight.Itwas,indeed,intriguedbythebait.It

is in a predator’s interest to be curious about its environment, and byinvestigating the squid bait, this giant squid was exhibiting classic predatorcuriosity.Kuboderagot so excited that he turnedon a flashlight to improvehisview.

Thegiantsquiddidn’t jetaway,soKuboderadecidedto takeabiggergamble.Heswitchedon the sub’sbrightwhite lightsand trained themon thecreature.The light turnedanastonishingevent into aprizedhigh-resolutionvideo.Thiswasthe“moneyshot,”asHollywoodwouldsay.Thisgiantsquid,ascaughtonvideo,seemedtohavealotofappendages,but

its tentacles were missing, perhaps lost to a fisherman’s line or during anencounterwith a spermwhale. Therewas no indication that the tentacles hadstartedtogrowback,soitmayhavebeenarecentincident.“Itwasabsolutelybreathtaking,”recallsWidder,“andhadthisanimalhadits

feedingtentaclesintactandfullyextended,itwouldhavebeenastallasatwo-storyhouse.”Forthenext15minutes,thegiantsquidhungaround“lookingbeautiful,”as

O’Shea said later. The team had documented the precious encounter on high-qualityvideo.Thehugelyexpensive,time-consuminggamblehadpaidoff.The expedition’s success reached and rocked evenWall Street, at least in a

minorway.Hedge-fundmanagerRayDalioproudlyannouncedthathisboatandsub had encountered a giant squid in its natural habitat and had succeeded infilmingitforthefirsttime.Notontheboathimself,DaliosharedtheexcitementandspreadthegroundbreakingnewsthelengthofManhattanandfarbeyond.“Theresultofalltheseexpeditions,”wroteAmericansciencewriterJennifer

FrazerinherScientificAmericanblog,“isthegrowingrealizationthatthegiantsquidisnotashy,retiringcreature,but it isnomonstereither. It isacomplexanimal thatwe have yet only a few tantalizing glimpses of. And the ultimateskirmishbetweenthespermwhaleandthegiantsquidremainstobewitnessedandcommittedtophotographorvideo.”Perhapsevenmorefrighteningthan thegiantsquidis theprospect that there

areseveralspecies.Sincethemid-19thcentury,some20speciesofgiantsquidhave been reported in scientific papers. In the 1980s, three valid specieswereproposed:Architeuthisdux, in theNorthAtlantic;Architeuthismartensi, in theNorthPacific;andArchiteuthissanctipauli, in theSouthernOcean.Since then,however, genetic studies have suggested that there is only one species,Architeuthisdux.

TheHumboldt,orjumbo,squid(Dosidicusgigas)hasalsohadsomemonstrousnessattributedtoit.Thissquid‘canbiteoarsandboathooksintwoandeatgianttuna

totheboneinminutes.’

totheboneinminutes.’

Whenunderattack,theAtollajellyfish(Atollasp.)producesbioluminescentflashesthateffectivelyworkasaburglaralarmtodrawlargepredatorswhich,inturn,feedontheAtolla’sattacker.Toattractsquid,bioluminescencespecialistEdieWiddercreatedanopticalelectroniclurewithblueLEDstosimulatethe

Atolla’sflashes.

Watchingandfilmingfromasubmarinein2012,worldsquidauthoritiesproducedthefirsteverhigh-resolutionvideoofthegiantsquidinaction.Onecuriousindividualjettedintoinvestigatethesquidbait.Fifteenminuteslater,theexpeditionhaditsprizedvideo,fromwhichthisstillimagewastaken.(©NHK/NEP/DiscoveryChannel)

ThetropicalOgasawaraIslandssouthofJapanareaprimelocationforthegiantsquid (Architeuthis dux) and for its predator, the sperm whale. An NHK-Discovery Channel expedition in June 2012 captured this rare image of theelusivesquid.Itisestimatedthatanindividualspermwhalemayeatuptothreegiantsquidaweek,butnoonehaseverwitnessedwhatsomecall theultimatebattleofthesea.(©NHK/NEP/DiscoveryChannel)

Yet there are other big squid. The colossal squid (Mesonychoteuthishamiltoni),whichhasbeenhauledupbyfishermenbuthasstillnotbeenfilmedor even seen alive at depth where it lives, is thought to be even larger andconsiderably fiercer than thegiant squid. Its tentaclesareshorter than thoseofthegiantsquid,givingitanoverallprobable lengthofupto30feet(9m),butbecauseof itsmassivemantle, finsandhead, thecolossal squid isheavierandbulkier.Thefiercenessofthecolossalsquidisamatterofconjecture,butarguinginits

favoristhepresenceofdozensofswivelhooksinplaceoftheusualsaw-toothedsuckersfoundonthegiantsquidandothersquidspecies.Swivelhooksgivethisanimaltheopportunitytosubdueamuchwiderrangeofpreythanthoseenjoyedbythegiantsquid.Thecolossalsquidresidesinsomeofthecoldest,darkestwatersintheocean.

To date, it has been found only in the Antarctic south of 40° S, roughly theterritorial limitof thegiantsquid.Maybe theymeetalong the lineandstareateach other with their big eyes. There are no recorded accounts of the twotogether.Thelargestknowncolossalsquidwasfoundfarsouth,intheRossSea,the coldest, iciest, most remote, southernmost sea on Earth. It is sometimescalled“thelastocean.”Noseaismoredeservingofcompleteprotectionasamarinereservethanthe

RossSea.Butafewyearsago,an“experimental”NewZealandlonglinefishingindustry that started catching the large, slow-growing Antarctic toothfish(Dissostichus mawsoni) here quickly got out of hand. Commercial fishermenfromothercountriessoonbeganarrivingtotakethetoothfish.ThisfishissoldasChilean seabass (buyer beware!) in themarkets of theworld to thosewhodon’tknowanybetterordon’tcare.RossSearesearchershaveknownforsomeyears that these nearly 50-year-old toothfish are important to Antarctic fish-eatingkillerwhales,butin2007,theylearnedthatanotherspeciesbesideskillerwhalesandhumansalsolovesthisfish.In 2007, New Zealand fishermen on the SanAspiring pulled up a colossal

squidstillattachedtoatoothfish.Thesquid’sswivelhookswerefirmlyplantedin the fleshof the fish itwas in theprocessofeating,and it refused to letgo.Whenfinallyseparatedfromitspreciousprey, thecolossalsquidwasfoundtoweighmore than1,000pounds(450kg)—therecordweight for thisspecies todate.After giant and colossal, what’s left?Well, the Humboldt, or jumbo, squid

(Dosidicus gigas) has also had some monstrousness attributed to it. The lateAmericansquidauthorityGilbertVossoncesaidthatthejumbosquid“canbiteoarsandboathooksintwoandeatgianttunatotheboneinminutes.”Uptosix

feet(2m)longandweighing100pounds(45kg)ormore,withbigmuscles,abroad tail fin and raw power, this squid has a certain fierceness. Yet squidresearcherswho’veworkedwithHumboldtsquidinrecentyearsplaydownanydanger, saying theywouldactuallybewilling toswimwith them.“Capableofmayhem”doesn’tmeanthattheywillnecessarilyattackhumans.Evenso-calledgentle whales have been responsible for accidental human deaths. Humboldtsquid are at home in theHumboldtCurrent off Peru andChile, butwhen thecurrent flows farther north, merging with warming seas, these squid startappearingasfarnorthasBritishColumbiaandevensouthernAlaska.

Withitsdinner-plate-sizedeyesandamantlebiggerthanthatofthegiantsquid,thisadultmalecolossalsquid(Mesonychoteuthishamiltoni)weighedinatabout1,000pounds(450kg)whenAntarctictoothfishfishermencaughtitaccidentallyintheRossSeainFebruary2007.Itisthelargestofthefewcolossalsquidfoundtodate.

For several years in the1930s and again in the late 1970s,Humboldt squidinvadedCaliforniawaters.Fishermenenjoyedthechancetocatchtheabundantsquid,whichweretwotosixtimeslargerthantheone-foot(30cm)marketsquid(Loligo opalescens) they usually caught. But albacore trollers found that theHumboldtsquidweresnatching thebait fromtheirhooksandgettingsnagged.Reportingonthefirstinvasion,R.S.CrokerwroteinCaliforniaFishandGamein 1937 that once the squidwere pulled into the boat, they often squirted thefishermenwith ink, shot jets ofwater at them and occasionally bit themwiththeirpowerfulbeaks.Mexican fishermen, more familiar with Humboldt squid from the warmer

Gulf of California waters, speak of the hungry calamar gigante with respect,almostas if itwereanhonortoloseone’scatchtotheHumboldtsquid.Thesesquid are sometimes so ravenous, they eat each other. Studies of the stomachcontents of stranded or freshly caught Humboldt squid have revealedcannibalism, though it isoften toodifficult to identifyanyremains.Likeothersquid,theHumboldtsquidhas“radular”teethonitstongueandpharynx,whichshredandpulverizethefoodbeforeitisdigestedinthealimentarycanal.Humboldt squid have also earned the respect of underwater photographers.

AlexKerstitchandHowardHalloncemadeanightdivewithHumboldtsquidinthe Gulf of California. Writing in the magazineOcean Realm in 1991, Hallreported that his diving buddy had been “mugged by a squid.” In fact, itwasseveralHumboldtsquid.HallandKerstitchwere30feet(9m)down,watchingathresher shark being pulled in on a fishing line from above,when a group offive-foot-long (1.5m) Humboldt squid—flashing rapid-fire strobes alternatingfrombrightredtoivory-white—attackedtheshark.Kerstitchjusthappenedtobein theway. “Frenzied by the smell of blood in thewater ... three large squidgrabbedAlexatthesametime.Suddenly,hefelthimselfrushingbackwardanddown.Atentaclereachedaroundhisneckandrippedoffhispre-Columbiangoldpendant and chain, tearing the skin on his neck. Another squid ripped hisdecompression computer off his pressure gauge. Tentacles tore his dive lightfromhiswristandhiscollectionbagoffhiswaist.Then,assuddenlyastheyhadgrabbedhim,thesquidweregone.”

‘Frenziedbythesmellofbloodinthewater...threelargesquidgrabbedAlexatthesametime.Suddenly,hefelthimselfrushingbackwardanddown.Atentaclereachedaroundhisneckandrippedoffhispre-

reachedaroundhisneckandrippedoffhispre-Columbiangoldpendant.’

AtnightintheGulfofCalifornia,aHumboldtsquid(Dosidicusgigas)jetstowardthesurfaceinsearchoffood:shrimp,lanternfish,mollusksandothercephalopods.TheHumboldtsquidcapturesitspreywithitssuckers,thenripsitapartusingitspowerfulbeak.

The self-assurance of this animal when encountered by divers, underwaterphotographers, fishermen, sailors and researchers makes the Humboldt a sea-monster candidate. Squid scientist Clyde Roper once received a bite thatpuncturedhisdivingsuitandhisinnerthigh,justinchesfromthefemoralartery.DiverandunderwaterphotographerScottCassellhasfilmedHumboldtsquidforyearsandwearsaspecialprotectivesuitwheneverhe’sinthewaterwiththem.Ontheotherhand,BillGillyofStanfordUniversityhasdivedwiththesesquidwithoutanyprotectionandneverhadaproblem.WhilestoriesofHumboldtsquidattacksappearinthetabloidpressfromtime

totime,thereisnoevidencetosuggestthatanysquidspeciesregardhumansaspotential prey.Most big squid are deep divers, living far from where humandiversventure.TheclosesttoapotentiallydangerousencounterisprobablywiththeHumboldtsquid,mostlybecausesomanyofthemcangatherinoneplace,alltrying to feed at once. Unlike the apparently solo-hunting giant squid, theHumboldt squid travels and hunts in packs—sometimes in whole flotillas.Imagine the Serengeti plains filledwith predator lions and hyenas rather thangazelles. This massive herd instinct may be responsible for the squid’sforbiddingreputationinsomecircles.Toseeasquidmightinspirewonder,buttosee40or50oreven500hyperactivesquid,someofthemshootingoutofthewater,isanothermatterentirely.ThenumbersofHumboldtsquidcrisscrossingone another’s paths at high speed create, more than anything else, a traffic-management problem. Swimming in themidst of such action, an adventurousdivermight easily get caught in aHumboldt squid traffic jam. It is surprisingthatmoredivershavenotsufferedinjuriesordeath.Almost all squid, in whatever food pyramid they are found, are voracious

predators. Their metabolism makes this a given. However, all are also prey,seekingtoavoidbeingeaten.Andthesetwofactorsdefinemuchofsquidlife.Squidpredatorsincludemostofthedolphinsandothertoothedwhales,seals,

sealionsandvarioussharks,plusmanylargefish,suchasmarlin,swordfishandtuna. They all depend on a number of squid species and may have speciallyadapted teeth, hunting or feedingmethods and habitat preferences dictated bytheirtasteforsquid.ThebelliesofswordfishinthePacificarefullofHumboldtsquid.Thedwarfspermwhaleand thepygmyspermwhale,bothofwhicharerelated to the spermwhale, are dolphin-sizedwhales that live off small squid.The spermwhale eats a number of squid species, butwithout the giant squid,woulditbeaslargeorassocialandwoulditdiveasdeep?(Othermembersofthespermwhalesocialgroupbabysittheyoungnearthesurfacewhenmothersdivedeepforsquid.)How do squid try to avoid predation? Besides their intelligence, sharp

eyesight and ability to react quickly and move fast, they use photophores tostartle and confuse potential predators. At depth, the suction power of thesuckersontheirappendagesisformidable,andsomesuckershaveringsofhardteethforextragrippingpower.Certainsmallsquidspeciesevenjumpoutofthewaterat times,producingthephenomenonknownas“flyingsquid.”Humboldtsquid are sometime fliers, making up for their weight and what they lack inaerodynamic shape with pure thrusting power. More than one Mexicanfisherman has had a Humboldt squid fly into his boat at night, photophoresflashingredandwhite,tentaclesreflexivelygrasping,thecreature’sbigeyesaswideassaucers.

♦

T

BigSharks2TheFleahEaters

HEY ARE CALLED “savage killers,” “assassins of the sea,”“mindlessmouthsofmurderousintent”and,mostfamouslybyauthorPeterBenchley,“perfectlyevolvedeatingmachines.”Suchepithetsare

difficult foragroupofanimals to livedown,much lesssurvive.Typicalsharkpredatory behavior, such as we know it, seems only to enhance the profile:Sharks are among the top hunters in the sea, and few animals are so wellequippedforthejoboffinding,pursuing,seizinganddevouringprey.Asharkcandetect“odorcorridors”thatcomefromwoundedanimalsandare

carriedformiles,dispersedbywindandcurrents.Onceonthescent,itclosesthedistancerapidly,thencirclestoinvestigate,honinginonitsquarryyettryingnottoalarmit. Itsbig,everwatchfuleyesseemtomissnothing.Theshark isalsoable to detect bioelectric stimuli produced by prey at close range, even if thatpreyisburiedinthesand,makingitvirtuallyimpossibleforprospectivepreytoescapenotice.Sogreat is the assault on the shark’s electrosense aswell as itsvision and smell that any sign of panic in prey is equivalent to dancingwithdeath.The finalmoments are no less frightening, as theoversized teeth close,convertingthepreytoconvenientfastfood.First, let’s considervision.Thepositioningof the eyesoneither sideof the

headallowstheshark toseeeverywhereexceptdirectly infrontandbehind.Ithashighlydeveloped irisesandpupils thatexpandwhenneeded to let inmorelight. Most impressive is that the shark can adapt to low light using rodphotoreceptorsforbasicvision,althoughitsabilitytoseedetailcanbepoorandit cannot see incolor.Tapeta,or reflective layers,behind the retina serveas asortofphotomultiplier, reflectingthe low-level lightcomingthroughtheretinaback to the light receptors and increasing it considerably.Thishelps the sharkfeedinthemurkydepthsandatnight.Next, thereis theshark’ssenseofsmell.Asubstantialportionof itsbrainis

devotedtosmell,andtheolfactorybulbsandlobesarepronouncedintheshark.Theolfactorysacslocatedunderthesnout,abovethemouth,arecoveredbythenasal flap, which funnels water into the sac chamber. There, it comes intocontactwith the sensory lamellae,which are linedwith receptor cells. Sharkshavebeenshowntoreacttofishextractsatconcentrationsofonly1partper10billionpartsofwater.Then there is the mysterious sense of electroreception—the shark’s

electrosensorysystem.Poresin theskinbeloweachof itseyesleadtothreetofivegrapelikeclustersoftheso-calledampullaeofLorenzini,orelectrosensoryorgans,allowingthesharktosample,atvariouslocationsonitsskin,thevoltageemitted by other creatures. All organisms have electrical fields or auras that,thoughoftenweak,canbepickedupbyasharkatcloserange.Withschoolingfish, the bioelectrical field may extend less than a foot (30 cm), while theelectrical fields produced by humans and larger organisms may carry a littlefarther.Asharkcandetectvoltagegradientsdowntofive-billionthsofavolt.Some of the small sharks that may be prey themselves can use their

electrosensetoavoidpredators.Andrays,closelyrelatedtosharks,arefamousfor their uses—and “misuses”—of electricity. The strong electrical fields andelectricalsignalsproducedbysomeraysallowapotentialmatetobe“spotted”evenwhenitisburiedinthesand.Butifaccidentallybumpedintoorsteppedon,those particular rays can deliver a painful jolt to unwary prey or a humanswimmer.Another method the shark uses to detect the subtle water movements of

potentialpreyisthe“lateralline”—aseriesofpitorgans,orclustersofsensoryhaircells,justbeneaththesurfaceoftheskin.Theorgansarelocatedaroundtheheadandinalinethatrunsalongtheupperflanks,orshoulders,oneithersideofthebodytothetail.Inthecaseofthestingray,theorgansthatextendalongthetailare thought toenable the ray todetectapredatorysharkapproachingfromtherear.A shark’s extremely acute tactile sense, picked up through the network of

nerveendingsbelowtheskin,canhelpthesharkdeterminethephysicalstrengthandhealthofitsprey.Evenatouchsolightthatitdepressestheshark’selasticskinbyaslittleaseightten-thousandthsofaninchcanbedetected.

Abronzewhaler,orcoppershark(Carcharhinusbrachyurus),feedsbesideaSouthAfricanfurseal.Inadditiontofish,thebronzewhalertakesawidevarietyofsquid,octopusesandrays,aswellasvariousbottomandmidwaterfish.Itisconsideredoneoftheeightmainsharkspeciesthataredangeroustohumans.

Thebullshark(Carcharhinusleucas),oneoftheeightsharksknowntobedangeroustohumans,usuallytravelsalonebutmaycongregatearoundproductivefoodareas,suchashereintheBahamas.Althoughthebullsharksometimesrangesintoriversandinlandlakes—oneindividualwasfoundliving

2,300miles(3,700km)uptheAmazonRiver—ittypicallyreturnstotheoceantobreed.

Itshearing,too,issharp,allowingthesharktobealerttoactivelyswimmingand,especially,strugglingprey.Roughlysimilartowhaleanddolphinhearing,ashark’saudiosensecanpickupsoundsthoughttobetransmittedthroughsoundpressurewavesthatentertheheadandarechanneledtotheinnerear.Armedwiththesesenses,thesharkwouldseemtoholdallthecardswhenit

comestopredationandhasdonesoforalongperiodofevolutionarytime.Theshark’s ancient ancestors of 400million ormore years ago were cruising theworldoceannearly200millionyearsbefore thedinosaurs.By the timeof thedinosaurs, theso-calledhybodontsharksbecamethedominantpredators in thesea,anditwasthediversificationofthesesharksintoeverycorneroftheworldoceanthatledtomostmodernsharkspecies.Sharkshaveplayedadominantroleintheecosystemsoftheworldoceaneversince.Anddon’tforgettheteeth.Originallyskintissue,sharkteethhaveevolvedto

be encased in an enameloid crown that forms a sharp cutting edge in somespecies and becomes crushing teeth with no cutting edges in others. Onecharacteristic of all sharks is that their teeth are constantly being replaced. Infact, the teeth are replaced so regularly that they have been called “conveyorbelts.”The sightofwhite sharks rammingunderwatercagesand rainingdownteethondivershasbecomealmostcommoninTVfootageofsharks.Ofcourse,theseanimalshavebeenluredtothecagesbybloodandoffalinthewaterinamix called “chum,”which stimulates their appetite, if not authentic predatorybehavior.Yetthelossandreplacementofteethisanaturalprocesswithsharks.Behind the front rowof teeth, new rows formandgraduallymove forward astheydevelop,replacingolderteeththathavebeenworndownorhavefallenout.That’s the conveyor belt.The teeth vary considerably from species to species,andaswithmanyanimals, they revealdietarypreferencesandareoftenakeydiagnosticindicationofaspeciesaswellasitsevolutionaryhistory.Inaddition,thesurfaceof theshark’sbodyiscoveredwithdenticles—tinytoothlikescalesno more than the thickness of a human hair—that point toward the tail andreducetheforcesofdragonthesharkbystreamliningtheflowofwateroverthebody.Finally, there is thematter of theOlympic-level athletic abilities of various

sharks. Thresher sharks have been filmed charging toward sardine shoals atspeedsofupto50milesperhour(80km/h),whippingtheirlongtailsovertheirheads and stunning or killing sardines caught in their path. In terms of long-distance travel, a young female white shark named Nicole shocked marinebiologists in early 2004when she surfaced inWesternAustralia threemonthsafter being tagged off Gansbaai, South Africa. Nicole then turned back andcompleted the 12,400-mile (20,000 km) round-trip by August, setting long-

distancespeedrecordsintheprocess.Most of the some 350 species of living sharks parceled into eight separate

orders are carnivorous as well as opportunistic scavengers, but only a few ofthem are the large predators that grab the headlines. Along with rays, sharksformthesubclassElasmobranchii(thosewithribbonlikegills),belongingtothelarger class of cartilaginous fish known as Chondrichthyes. Cartilaginous fishhave skeletons that are mainly cartilage rather than calcified bones. Besidesconveyor-belt teeth, the elasmobranchshaveanupper “floating” jaw,which isnotrigidlyfixedtotheskullbutsuspendedbyligaments,fivetosevenexternalgillslitsoneachsideoftheheadandplacoidskinscalescalleddenticles.Measuring3to10feet(1–3m)long,atypicaladultsharksubsistsonadietof

fish, including other sharks—sometimes even its own species. Its foodpreferences and feeding habits depend on that particular species’ niche,includingitshabitatandrangein thesea.Thereare threemain typesofsharksclassedaccordingtotheirhuntingstrategies:pursuitpredators,ambushpredatorsand bottom foragers.Nomatter the species, the typical shark generally showslittle interest in human divers and swimmers, except when its curiosity orappetite is stimulated accidentally or on purpose. It is the exceptions—thoserogueswhichmaketheheadlines—thathavegivensharksabadname.Thesearethelargecarnivoroussharks,whichincludetheso-calledrequiemsharksandthewhiteshark,atupto21feet(6.5m)long.There are arguably only eight truly dangerous human-attacking sharks: the

whiteshark,thebronzewhaler,thebullshark,theduskyshark,thetigershark,thegreathammerhead shark, theoceanicwhitetip sharkand the shortfinmakoshark. Another eight are dangerous if prodded, stepped on or cornered: theornatewobbegong,thetasselledwobbegong,theCaribbeanreefshark,theblueshark, the whitetip reef shark, the Greenland shark, the broadnose sevengillshark and the sand tiger shark. However, about half of the sharks on thisdangerous-if-prodded listhaveneverbeenknowntoattackahuman.Themostdangeroussharksarethoselikethewhite,whoseprey(seals,elephantseals,sealions) roughly resembles humans in size and location (inshore waters), andoceanic whitetip sharks, whose open-ocean habitatmeans that theymust takewhat’s on offer. Some shark attacks on humans may be a case of “mistakenidentity,”thoughwiththeiradvancedsensoryequipment,sharksprobablyhaveagoodideaofwhatisorisn’tahuman.Nevertheless,humandiversmightbecomepreywhentheydiveinmurkywatersnearasealcolony.Besideslookinglikesharkpreyorfindingyourselfinashark-richportionof

theopenocean,thefollowingcanstimulatepredatorybehaviorinthewater:

openwounds,especiallyifthey’rebleeding;theflashofshinyequipment,clothingorjewelry,whichmightresemblefishscales;surprisingasharkbyfallingintothewaterwhilesailing,surfingordoingsomeotheractivityintheocean;unusual,erraticorpanickedswimmingbehavior,includingsplashingandtheill-advisedmadretreatuponseeingashark.

Manyoftheaforementionedbigsharksrangeintheuppermostwatersofthesea, from coastal to open-ocean, or pelagic, waters, which is why they’reoccasionallydangerous topeople.During theSecondWorldWar,manyof thecasualtiesfloatingorswimmingfortheirlivesaftertheirshipsweretorpedoedinthePacific theater are thought to have been taken by pelagic oceanicwhitetipsharks.Othersharks,includingmanysmallspecies,liveinthedeeplevelsofthesea.

Thelargestandpotentiallymostdangerousis theGreenlandshark,whichpliesthe cold, deepwatersof theNorthAtlantic.Buthumans are simplynot in thehabitofdiving1,800feet(550m)inthewatersoffGreenland.The large ocean carnivores, located two or three big steps down the food

chain,seemfarremovedfromcopepodsandotherzooplankton,althoughmanyof the animals they devour depend on copepods.Yet in the bizarre catalog of1,001usesfortheubiquitouscopepod,theGreenlandsharkdoes,infact,haveanintimaterelationshipwithit.TinycopepodsattachthemselvestothecorneasoftheGreenlandshark’seyes

anddevelopwhat seems tobea symbiotic relationship.Alsoknownasoneofthe sleeper sharks, this deep-water, slow-moving, up-to-21-foot-long (6.5 m)dogfish lives 1,800 feet (550 m) or more beneath the surface. In these darkwaters, thecopepodsontheireyesare luminescent,whichmayattractsomeofthe shark’s prey, ranging from curious deep-diving seals to a wide variety ofbottom-dwellingfish.Whilethesharkmayappeartobeasleep,itremainsalertandeverwatchfulforpotentialprey,seizingitwhentheopportunityarises.

Ashumansknowwell,thefiercestcompetitionisusuallywithmembersofone’sownspecies,whohavethesamerequirementsforfood,space,waterandothernecessities.Thismayexplaintheoccasionalinstancesofcannibalisminsharksandthewide-ranginghabitsof

ofcannibalisminsharksandthewide-ranginghabitsofthoseatthetopofthefoodpyramid.

Recent clues about the reproductive behavior of the Greenland shark haverevealed that the female bears about 10 pups in each litter. As a yolk-sacviviparous shark, the female incubates the eggs in her body, where the pupshatch and emerge as well-formed young. Most shark species are yolk-sacviviparous. Some, however, are viviparous species, in which the embryosdevelopinsidethefemalebutnotwithineggcases.Bothsystemsaremarkedbylowbirthrates,morelikethoseofwhalesandothermammalsthanthoseofmostfish,which typically lay thousandsofeggsata time.Matingoften takesplaceduringaparticularseasonorperiodeveryyear.Themalesharkusesitsclasperorgans to enter the female’s cloaca and drive its collected sperm deep inside.Dependingon the species, thegestationperiod lasts from threemonths to twoyears. Several bizarre features have contributed to the legendary status andmonstrous image of some sharks. The firstborn sand tiger shark, for example,proceeds to eat its smaller siblings inside its mother’s womb as well as theunfertilized eggs she continues to produce. This is sibling rivalry taken to theextreme.As humans knowwell, the fiercest competition is usuallywithmembers of

one’sownspecies,whohavethesamerequirementsforfood,space,waterandother necessities. Thismay explain the occasional instances of cannibalism insharksandthewide-ranginghabitsofthoseatthetopofthefoodpyramid.Ina typical foodpyramid ina typicalecosystem, theprimary,orbase, level

hasthegreatestnumberofindividualsandtheapexhasthefewest.Andsoitiswith sharks,whereinmost species arenearor at the apex.Toppredatorshavebuilt-in biological controls, honed and modified by evolution, which helpprevent their numbers from becoming so great that their environment isovereaten.Sharksproducefeweryoungthanotherfishorsmallerorganismsandtend to have much larger territories, or home ranges. They must cover moreground in their search for food, and if they can effectively keep competitorsaway or avoid them—both related species and other top predators—then theycanensuretheirownsurvivalandthatoftheiroffspring.All these carnivorous top-predator sharks, however, are small stuff when

comparedwith a certain extinct relative that is often referred to simply as thegiant shark, ormegalodon (Carcharodonmegalodon). It’s in the same family

(Lamnidae) as the white shark. Megalodon means “big teeth.” The largestmegalodonteethdiscoveredtodatearenearlyeightinches(20cm)long,whilethoseofthewhitesharkmeasureamerethreeinches(7.6cm).Thesehugefossilizedteeth,stillfoundontheseabed,areall thatremainsof

thiscolossalanimal.Althoughtheactualbodysizeisaguess,itmayhavebeenmore than 50 feet (15m) long, weighing some 25 tons (22,700 kg)—severaltimes thebulkof thewhiteshark.The teethare found in fossilsdating from3million to 25 million years ago, though wishful speculation sometimes leadsgiant shark enthusiasts to give more recent possible dates. By far the largestsharkever,megalodoncouldwellbe theultimate,magnificent, trulymenacingseamonster.Regrettably,itnolongerlives.

♦

Distinguishedbyaflattened,hammer-shapedheadcalledacephalofoil,whichmayhaveevolvedtoaidvision,hammerheadsharkscomprise11speciesinthefamilySphyrnidae.Mosthammerheadsposenodangertohumans.InnativeHawaiianculture,hammerheadswereconsideredoneofthe'aumakua,orprotectorsofhumans,ratherthanman-eaters.

Reachinglengthsof20feet(6m),theGreenlandshark(Somniosusmicrocephalus)livesintheNorthAtlanticandArctic,whereithasbeenfounddivingtodepthsof1.4miles(2.2km).Thislargesharkbelongstothemodestgroupofsleepersharksthatareknownfortheirlargelivers,whichhaveprovedattractivetooffshorekillerwhalesintheNortheastPacific.Two-inch(5cm)parasiticcopepods(Ommatokoitaelongata)oftenattachthemselvestoeitherorbothoftheshark’scorneas.

I

KillerWhalevs.Shark

NTHISCORNER,we have a 10-to 13-foot (3–4m)white shark, smallcomparedwiththemaximumlengthof20feet(6m)knownforthespeciesinthisareabutwellequippedwithsome3,000razor-sharpteetharranged

inseveralrowsthatrotatetowardthefrontofitsmouthasthefrontteethbreakoff.In the opposite corner, at 15 to 17 feet (4.5–5m),we have a female killer

whale,ororca, lookingsmartandsleekbuthardlymenacing.Sherarelyopenshermouth, butwhen she does, she reveals up to 48 interlocking banana-sizedteeth.OnOctober4,1997,atpreciselyhighnoon,awhitesharkappearedalongside

an Oceanic Society whale-watching boat, the New Superfish, off SoutheastFarallon Island, near San Francisco.White sharks are commonly seen in thisarea—some35ofthemhavebeenindividuallyidentifiedfromnaturalmarkings.Theytypicallystaydeepinthewatercolumn,comingtothesurfaceatanysignof a distressed or injured California sea lion, northern sea elephant or otherpinniped.Thekillerwhaleinthismatchwaspartofapodknowntofrequentsouthern

California waters. Dubbed the “L.A. Pod” by photographer-researcher AlisaSchulman-Janiger, who followed the pod intensively during its frequentappearanceson theLosAngelesoceanfront from1982 to1997, thegroupwasnot common to theFarallon Islands area,which is primewhite shark country.From photos, the female was identified as CA2, and she was traveling withanotherfemale,afrequentcompanioncalledCA6.Thepodoccasionallyfedonmarinemammalprey, andonlyanhouror soearlier,CA2andCA6hadbeenseeneatinganadultmaleCaliforniasealion—justthesortoffoodwhitesharksalsoenjoy.Onpaper,itmightseemthatorcaswouldgivethe“Jawsshark”awideberth,

ifonlytoavoidbrushingagainstitsroughskinorbeingbittenbythatmouthful

of3,000teeth.Thereweretwofemaleorcasandonlyoneshark—aclassiccaseoftwoagainstone—butjustoneoftheorcasshowedaninterestintheshark.White sharks have been known to feed on largewhales, such as finwhales

and sperm whales, and on bottlenose and other dolphins, but there was norecordedcaseofwhitesharksandkillerwhalescomingtoblows.Untilnow.Killer whale vs. white shark. Would this be a battle royal—the ultimate

predator-prey contest in the sea? But which one was the predator, which theprey?Whale-watchingguidesMaryJaneSchrammandCarolKeiperwitnessedthe

subsequent encounter and outcome from the boat. It was an almost instantknockdown. The female orca quickly surfaced with the shark’s back in hermouth.Holding theanimalupsidedown todisable it,perhaps toasphyxiate it,sheswamonthesurface,thesharkheldhighlikeatrophy.Therewerenobitewounds,noblood.Theorcahadlikelyslammedintothesharkunderwaterbeforepushingitslifelessbodyupandoutofthewater.Ithadhappenedsofastthatthesharkhadnotimetorespondtoanyelectrosensecuesitmayhavereceived.Andso the first ever recorded killer whale and white shark tussle was over. The“victor”wasafemaleorcafromtheL.A.Pod,andthesceneofthekillwasonlyafewhundredmilesfromHollywood,groundzerofortheJawsmythology.Some 18 minutes after the initial kill, Peter Pyle of the Point Reyes Bird

ObservatoryarrivedinaBostonWhalerwithavideocameraandshotthevideothathasnowbeenseenbysome3.8millionpeopleonYouTube.Pylerecordedthefemaleorcastillcarryingthesharkinhermouth.Fiveminuteslater,whenalargesectionoftheshark’sliverbecameseparatedfromtherestofthecarcass,CA2 finally let go and went straight for the liver. Pyle observed that CA2’srostrumhadbecomechafedandstainedwithblood.After thekillerwhale/shark incidentoffSoutheastFarallonIsland,nearlyall

the30-someresidentsharkslefttheareafortherestoftheautumnmonths.TheL.A. Pod visited the area several more times during this period but made nomoresharkkills.Since1997,however,theL.A.Poditselfhasdisappeared.Thewhales may have returned to Mexican waters, but no sightings have beenreported.Orcas are well-known predators of other shark species. In various papers,

researchersIngridVisser,DagmarFertlandothershaverecordedbasking,blue,school and shortfin mako sharks as orca prey, the latter observed in NewZealand waters by Visser and colleagues when a known pod of local NewZealandorcasattackedthem.Thesharksseemedtotrytohidenotonlyaroundtheresearchers’boatbutaroundVisserherself,whowasinthewaterwitnessingtheaction.

IntheeasternNorthPacific,orcasmaybesharkspecialists.Killerwhalesintheecotypeknownasthe“offshores”spendtheirdaysfaroutonthecontinentalshelf and have long been suspected of being shark hunters. Researchers JohnFord,GraemeEllisandothers,whohaveobtainedandanalyzedbiopsiesoftheoffshorewhales,havenotedthatthefattyacids,persistentorganicpollutantsandstableisotopesallindicateadietofsomelong-livedfishhighinthefoodchain.Intheoddoffshoreorcafoundstranded,theresearcherswereamazedtoseetheseveretoothwearexhibitedinsomecarcasses.Thetoothenamelwasworndowntothegumline,exposingthepulpcavities,probablyfromtheroughsharkskin.Ford and Ellis observed the offshores on the continental shelf off British

Columbia in 2008 and 2009. The whales left massive liver-oil slicks on thesurface,which convinced the researchers that these offshore orcaswere sharkspecialists.DNAanalysisoftissuesamplescollectedatthekillsitespointedtotheup-to-seven-foot-long(2m)Pacificsleepershark(Somniosuspacificus).The areas favored by the offshore orcas also support large numbers of blue

and salmon sharks aswell as smaller dogfish.Theorcas’ preference for sharkliverprovidesthewhaleswithoneofthemostconcentratedsourcesoffatandoilinthesea.Themassiveliversinsomeofthelargersharkspeciesaretheresultoftheir extensive predation onmarine mammals. Recently, the livers have beenshown to contribute to the shark’s buoyancy and are essential for long sharkmigrations across nutrient-poor areas, such as thewhite’s 12,400-mile (20,000km)round-tripsacross theSouthernOcean.Thussharkspecieswith livers thatmayoccupyupto80percentoftheirbodiesbecome,inturn,theessentialfoodforapicky-eaterecotypeofkillerwhales:theoffshores.

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Awhiteshark(Carcharodoncarcharias)swimsnearGuadalupeIsland,Mexico,aprimehuntinggroundforsealandsealionprey.Probablythemostfearedofsharks, the white shark appears to be slow-growing (maturing at age 17, onaverage)and long-lived (toage30,at least). It is categorizedasvulnerableby

conservationists.

Membersofthetransientkillerwhalegroupcalledthe“L.A.Pod”weresouthernCaliforniaregularsfrom1982to1997.Oneofthepod’sclaimstofamewasitsvisitfarthernorthtotheFarallonIslands,offSanFrancisco,wherethematurefemaleorcaCA2tangledwitharesidentwhitesharkinabattleroyal.

A

DownDeepwithDragonfish

NOTHERAGGRESSIVEandvoraciouspredatorlivesintheseathatisneithersharknorsquidnorevenkillerwhale.Someattentionmustbepaid,infact,toalesser-knowndeep-seagroupoffishthatrangein

lengthfromlessthan¾inch(2cm)toabout20inches(50cm).MeettheorderoffishcalledtheStomiiformes:thedragonfish.Thecommonnamesof theapproximately250speciesknown todate in this

group,whichcontainsfourtosixfamilies,revealtheirfierce,predaceousnature.Besidesthevariousdragonfish—thenamethatisoftenusedfortheentireorder—there are viperfish, hatchetfish, snaggletooths and loosejaws, but many ofthese specieshaveno commonnamesbecause they areuncommon, even rare.These fish live in mid-to deep waters and thus are rarely encountered bymariners, fishermenorotherswhowouldaward themacommonname.That’sfortunate, asachancemeetingwithadragonfishanda subsequentattackonadiver’s feet or a fisherman’s hands could certainly prove painful if not life-changing.Howmuchofahumancouldbeswallowedbya20-inch(50cm)fishis uncertain, but surely enough to do a lot of damage. On the rare occasionswhendragonfishhavebeenseen,theyhadbeencontortedbythedrasticpressurechangeastheywerepulledtothesurfacedead.Themysterious dragonfish, which have long bodies and tend to be dark in

coloring,arenothigh-profilepredatorslikethesharkorthegiantsquid,buttheywell deserve the few common names they’ve been awarded. Althoughdragonfishdon’tbreathefire,theyhavenumerousflashingphotophorestoattractor illuminate prey, confuse potential predators and communicate with othermembersoftheirspecies.Dragonfisheatanythingandeverything,evenfeedingon animals larger than themselves. This feat is accomplished through acombinationofhingedteethandspecializedjawsthatcanexpanddramatically.Hatchetfish, part of one branch of the order, actually have small teeth and

appear to feedmainly on plankton. They undertake verticalmigrations, rising

withthedimminglightofeveningtofeedinshallowerwatersandreturningtothe deep during the day. But their low-key existence is more the exceptionwithin theorder.Themostcommonandbest-knowndragonfishare theclassicbig-toothed predators of fish, squid, crustaceans and anything within strikingrange.Theyremainatdepth,waitingfor thehatchetfishandothermigrators toreturn from a night of feeding, then devour the equivalent of a hearty room-servicebreakfastinbed.Dragonfish teeth look like shards of glass. In some species, the lower teeth

actuallyextendupandovertheheaditself.Inotherspecies, thelowerteethfitintodeepchannelsthatrunfromtheroofofthemouthintotheheadalongeithersideofthebrain.Theteethdon’tgetintheway.Theyhaveevolvedtograbandlockonsecurelytoprey.Theyarealsodesignedsothatthefishcanfullyopenitsmouth toacquireprey larger than itself.Once theprey is in themouth, theinternalskeletonof thepectoral finscanbe lowered,enabling theprey topassintothegullet.Thestomachisextremelymuscularandcanexpandasneeded.Insomespeciesof loosejaws, there isnobottomto themouth.Tomanageabig-fishmeal,acolumnofmusclewithtissuebetweenthelowerjawandgillbasketcontractswhenthepreyissafelyinside,closingthemouth.Dragonfish try to avoid predation themselves through black stomach walls

thatkeepthephotophoresoftheirpreysafelyhiddenduringdigestion.Theyalsoremainatdepth,wheremostpredatorseithercannotseethemorareconfusedbythedragonfish’sownphotophores.

ThePacifichatchetfish(Argyropelecusaffinis)ascendseverynightfromadepthof 1,000 to 2,100 feet (300–640m) to catch its planktonic prey in shallowerwaters. Its huge eyes are an adaptation to the twilight. Photophores along thebottomofthefishemitbluelightatawavelengthinvisibletopredatorslurking

below.

Thenorthernstoplightloosejaw(Malacosteusniger)livesinthemesopelagic“red-lightdistrict,”whereonlycertainfishcanemitredlightandseeit.Usingitsredlight,M.nigercanspotlightpreywithoutbetrayingitspresencetoanycompetitorpredators.Eventhepreydoesn’trealizeithasbeenfloodlit.

Thecharacteristicbarbel, found inmanydragonfish,extendsdownfrom thechin or lower jaw and can be moved using muscles behind the jaw. Oftenbioluminescent, the barbel has several possible functions. It may confusepotential predators by making the dragonfish appear larger or in a differentposition. Additionally, it might allow dragonfish to communicate with oneanother.Butmainly,thebarbelactsasa“fishingpole”thatattractscuriouspreyto inspectwhat turnsout tobeamouthfulofengulfing teeth. Insomespecies,thelureevenimitatesappealingfoodforunsuspectingfish.Some dragonfish prefer to nibble delectablemorsels nearer the base of the

foodpyramid.EventhoughMalacosteusnigeriswellequippedwithavariationof the needle-sharp teeth and hinged jaws found throughout the mesopelagic,there is evidence to suggest that copepods may be its main diet. Perhaps itsupplementsthatdietwithmuchlargerprey,ormaybethebigteetharesimplyleftoverfromdietaryhabitscommoninitsearlierevolutionaryhistory.Butthisdragonfishmayincludecopepodsinitsdietformorethanjusttheirfoodvalue.Thereasondragonfishmayhaveanappetiteforcopepodswaspartlyrevealed

by vision research published in 1998. Researchers RonH.Douglas, Julian C.PartridgeandothersatCityUniversityLondon,inEngland,andtheUniversityof Bristol discovered that the dragonfishwas acquiring and using chlorophyllfromitsdietofcopepods,whoseownphytoplanktondietcontainsbacteriawithchlorophyll.Noknownanimalcansynthesizechlorophyll—that’saplant’s job—yet the retina of the dragonfish has substantial amounts of a derivative ofchlorophyll that is used as a photosynthesizer which is essential to the fish’sabilitytoseered.Insomeyet-to-be-determinedway,thedragonfishincorporatesthechlorophyllintoitsretina.

Theideaisthatthesedragonfishusetheredlightastheirownsurveillanceandcommunicationsystem.

Thustheycanilluminatepreywithoutbeingseenbythepreyandcanpasssignalstooneanotherbyflashingtheirredlights,whichareinvisibletoallothers.

Inearlierwork,DouglasandPartridgedeterminedthatM.nigerandtwootherspeciesofdragonfishproduce and see red lightdeep in themesopelagic zone,

where only blue light was thought to exist. These fish have two sets of lightorgansontheirheads.Apairofphotophoresbehindeacheyesendsouttheusualblue-greenlight,asdootherfish,whilealightorganbeneatheacheyesendsoutlightintheredpartofthespectrum.Theideaisthatthesedragonfishusetheredlight as their own surveillance and communication system. Thus they canilluminate prey without being seen by the prey and can pass signals to oneanotherbyflashingtheirredlights,whichareinvisibletoallothers.Humanscanjust barely see the red glow produced by the deep-sea dragonfish generaAristostomias and Pachystomias, but the reddish hunting searchlights of M.niger are so far into the red spectrum, they can be seen only by using specialscientific instruments—or by another dragonfish. Welcome to the red-lightdistrict.Thestoryof thisfishshowsthatatgreatdepths,whereyoucan’tsee toeat,

youmayhavetochooseyourfoodspecially—toeatinordertobeabletosee.

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Boastinglight-emittingorgansbeloweacheyeandalongthelowerpartofitsslenderbody,theblackdragonfish(Melanostomiasmelanops)usesitsfleshybioluminescentbarbeltolurepreycloser.Thisone,measuringafoot(30cm)long,wasfoundat6,600feet(2,000m)offtheCapeVerdeIslands.

K

TheWeb

RILLSTANDSasoneof themost important, fundamentalpartsoftheglobalfoodchain.And so, a larger story begins to emerge. The copepod and the

planktivorous shark sometimesmeeton thebattlefield,munching sideby side,and more often than not, the copepod is ingested by the big shark. Baskingsharksdonothavetimetobetoochoosyabouttheoddcopepodintheirdinner.Nor do jellyfish, which have to wait for the unwary. Fish that are often notchoosy—generalfeedersonwhateveroftherightsizeswimsbyorcanbecaught—thriveaslarvaeonplanktonexplosionsandgrowfat.Andthepredatorsharksandthegiantsquid,ofcourse,goinsearchofthesefattenedfish.Spermwhalesgo for the squid and a bit of fish, while killer whales, depending on theirecotype, focus on fattened fish, squid, sharks, including the white shark, andeventhemuchlargerbluewhale,spermwhaleandotherwhales.Thedragonfishmostlytakewhatevertheycanget,whateverswimspastordriftsdownintothemid-todeepwaters.Infar-flungareasoftheocean,thedetailsofthestorydiffer.Whilekrillrefers

to dozens of species that provide food for fish, squid, ctenophores, penguins,seabirds,sealsandwhales, including the largestbluewhales, largepartsof theAntarcticecosystemareutterlydependentuponasinglekrillspecies.AfemaleAntarctickrill (Euphausia superba), about two to three inches (5–7.6cm) longand filter-feeding on plankton, is very productive, laying 10,000 eggs severaltimesayear.ThiskrilllivesallaroundtheAntarcticinhugeswarmsoftensofthousandspercubicmeter(264gallons).TheAntarctickrillemitsburstsofbluebioluminescencefrompairsofpivotinglightorgansalongitsbody,eachorganequippedwithalensandareflector.Italsohasanotherpairoflightorgansonitseyestalks. Researchers Thérèse Wilson and Woody Hastings suggest that thebioluminescentflashingmayallowthekrilltokeepintouchwithoneanother.Ifso, this is a perfect situation for a hungrywhale, seal or colossal squid. Blue

whales,inparticular,needconcentratedpreytomeettheirenergyrequirements.Thusbluewhales,perhapsnavigatingtothisspotandcallingacrosstheoceantootherbluesusingthelongest-rangecommunicationsystemonEarth,proceedtodevourtheseoceanfirefliesbythemillions,gratefulthatakrill’scommunicationsystemworkssoconvenientlytogathertheirdinnertogether.

Manywhales,seabirds,squidandfishintheNorthAtlanticdependonthevastswarmsofnorthernkrill(Meganyctiphanesnorvegica)forallormostoftheirfoodneeds.Theintenseredcolorofthestomachareaofthebioluminescentkrillsuggestsithasbeenfeedingoncopepods.

InSeptember2013,apopulationexplosionofnorthernanchovies(Engraulismordax)inMontereyBay,California,producedthisfeedingfrenzy,withhumpbackwhaleschargingupthewatercolumn,mouthswideopen.ThehumpbackswerejoinedbyhundredsofCaliforniasealionsandwesterngullsintentonsharingthespoilsand,intheprocess,creatingascenethatresembledamarineSerengeti.

Alltheseandotherfoodpyramidsorchainstakentogether—whichisthesumofeverypathwaybywhichenergymovesthroughecosystems—makeuptheso-called foodweb. As scientists learnmore about the foodweb, its complexityincreases by the decade. The well-studied Benguela ecosystem off southwestAfricahasrecentlybeenshowntohaveatleast28millionpathwaysthroughitsfood web, which includes fur seals and various sharks as well as suchcommerciallyvaluablefishashakeandtuna.Yetthemiracleisthatonewayoranother,thefabledgiantsquid(theworld’slargestinvertebrate),thewhaleshark(the largest fish in the sea), the giant siphonophore (the longest animal in theworld),thewhiteshark(thesea’smostfearedpredator)andthemuch-lovedorca(thesea’smost formidablepredator)all traceapathway, inahandfulof smallsteps, to the largelymicroscopicphytoplanktonanddependutterlyupon itandonthesuccessofthecopepodsandotherzooplankton.Inasimplifiedfoodpyramid,itisassumedthateverythingonagivenlevelis

entirely consumed by the next level of organisms. In fact, there is much thatescapes. Phytoplankton and zooplankton, for example, drift out of reach ofpredators at one level and eventually fall, providing useful food sources fordeep-living animals andmicroorganisms. By some combination of cleverness,athleticism and luck, the giant, the colossal and even, to some extent, theHumboldtsquidmanagetokeepgrowingandgrowing.Butthecrucialpointisthatbyescapingpredation,plankton,aswellasnekton,

thefree-swimminganimalshigherupthefoodpyramid,cansurvivetoreproduceand pass on their genes to the next generation. The animals that manage toescape thefoodwebareeverybitasvitalas theanimals thatbecomefoodforotherspecies.Andso,lifeevolves.

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PARTTHREE

Previous page: This squat lobster, a member of the Galatheidae family, wasdiscovered grazing on black fan coral during a December 2011 exploratorycruisealongtheSouthwestIndianRidgeintheIndianOcean.

TheriftvalleyoftheMid-AtlanticRidgecomesashoreinIceland,passingthroughthenationalparkatÞingvellir,thesiteoftheAlþingi,theIcelandicgeneralassembly.Foundedin930AD,itistheoldestparliamentintheworld.

A

TrekkingDowntheRidge

T2,000FEET(610m)abovesealevel,juststepsfromthemainroadthat crosses the Krafla area of northeastern Iceland, I am walkingthrough a part-lunar, part-Venusian landscape, Iceland’s most

awesomelavafield.Krafla’srecentspateofvolcanicactivitybeganin1975withsome nine eruptions over the next decade. By the 1990s, the great magmachamberjustbeneathmyfeetwasbeginningtoriseupagain.Althoughit’snotmoving at the moment, the assorted steam vents, boiling springs, fumaroles,sulfurdepositsandbubblingmudpotsaroundmeareproofthatactivitycarrieson.Now,approachingthesummit,IcanseeDalfjall.Ratherthanamountainous

peak, it is ahugenotch:RavensNotch. I stop togapeat thegap. Ihavebeenherethreetimesbefore,mostrecentlythreeyearsearlier,whenthegapwasthreeinches(7.6cm)smaller.Thesightofitstilltakesmybreathaway.Forthisisthespotwhere theMid-Atlantic Ridge—the underwatermountain range that runsdownthecenteroftheNorthandSouthAtlantic—revealsitselfonlandinallitsgeologicalglory.RavensNotch growswider every year and is evidence that themountain is

slowly being pulled apart, as is Iceland and theEurasian andNorthAmericantectonic plates, which face each other across the ever-widening Mid-AtlanticRidge. Fortunately for Iceland, the island itself will not split in two becausevolcanic activity repairs the rift as the plates move apart. Still, in anotherhundredyearsorso,thegapcouldpossiblyhavewidenedbyanadditionalsevenfeet(2m),althoughthemovementhappensinfitsandstarts.IntheKraflaarea,themost intensive bursts of activity were in 900AD, 1724–29 and 1975–84.Duringthoseperiods,RavensNotchmighthavewidenedbythreetosixfeet(1–2m)inadecade.Intheperiodsbetween,themovementhasbeenlessdramatic.Itmaynotseemmuch,butsuchisthewaythatlandmassesshift,rupture,split

apart and re-form overmillions of years. The journey of geological time, the

pathofnewcontinents,beginswithan inchayear.Here in Iceland, as in fewplacesonEarth,onecanexperienceviolentgeologyonaregular,oftenalarmingbasis.StrollingtothesummitofnearbyNámafjallRidge,Icanlooksouthwestalong thegreat seriesof fissures in theEarth—someburiedunder iceor rock,others all too visible—on a course across Iceland that leads toward the Rey‐kjanesPeninsula,nearReykjavík.

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AtRavensNotchonDalfjall,innortheastIceland,theEurasianandNorthAmericantectonicplatescanbeseentobesplittingapart.

Partoftheland-basedextensionoftheMid-AtlanticRidgeinIceland,theEyjafjallajökullvolcanoeruptedinearly2010.ThespreadingplumeofvolcanicashdisruptedairtravelthroughoutEuropeandtootherpartsoftheworldforseveralweeks.

L

TheLongestMountainChainintheWorld

ET’SIMAGINEajourneythatproceedsalongthetopofthespreadingMid-Atlantic Ridge. Traversing Iceland on foot, we move throughsome of the newest lava fields in theworld. Iceland is so active, in

fact,thatone-thirdofallthelavawhichhascometotheEarth’ssurfaceoverthepast 1,000 years has done so in Iceland.The youngest rocks and lava, tens tohundredsofyearsold,arefoundalongtheridge,whiletheeastandwestcoastsof Icelandareon theorderof16millionyearsold.Thusaspanofmillionsofyears can be traversed in a few hours by car on roads that have been carvedthroughfieldsofveryslowlyspreadinglava.InthecenterofIceland,wecrossthe edge of Vatnajökull, the largest ice cap in Europe, at 3,200 square miles(8,300km2).WepassKatlaandthesmallerEyjafjallajökull,thevolcanowhoseeruptions beginning in March 2010 cost airlines and related industries anestimated$1.7billion(U.S.)asaresultofdisruptionsintravelschedules,mainlyin Europe. Eyjafjallajökull is part of the chain of volcanoes fed by a magmachamberthathasformedduetothespreadingoftheMid-AtlanticRidge.Then,asweheadsouthwesttotheReykjanesPeninsula,wepassmorefreshlavafieldsskirtingthefamousBlueLagoonnearReykjavík,whereruddy-faced,sometimesblue-lippedswimmersenjoythehotspringsthatjustseveralhundredmilessouthonthisridgewouldbedeep-seahydrothermalvents.NeartheinternationalairportatKeflavík,theridgeabruptlygoessubmarine,

droppingfrom0to660feet(200m),buttheheightandpersistenceoftheridgeeffectively delay the drop to the 3,300-foot (1,000 m) contour for severalhundredmilessouthwestofIceland.Astheridgedipsdeepbeneaththesurface,it assumes the geographical appearance and name better known to modernoceanographersandgeologists:Mid-AtlanticRidge.

OnitswaydowntheReykjanesPeninsulatothesea,theMid-AtlanticRidgepassesthroughthegeothermalBlueLagoon.

Sometimesreferredtogloballyasthe“midoceanridge,”thismountainrange—46,000 miles (74,000 km) long in its entirety—is 11½ times longer than theAndesofSouthAmerica,whichisthelongestmountainrangeonland,at4,000miles (6,400 km). TheMid-Atlantic Ridge soars up to 15,000 feet (4,600m)abovetheabyssalplainandcanbe1,000miles(1,600km)widebeforeturninginto abyssal hills several hundred feet high and finally spreading out into theabyssal plain. Onemight say it is amountain rangeworthy of amuch largerplanet,although,asweshallsee,themidoceanridgehasthesortofgeographicalpeculiaritiesandwondersthatbefitanoceanplanet—Earth.Onamuchsmaller,drierscale,wemightcompareourimaginaryventurewith

awalkalongtheAppalachianTrail,intheeasternUnitedStates.At2,100miles(3,400km)long,theAppalachianTrailextendsalongtheold,roundedpeaksoftheAppalachianMountains, fromMaine toGeorgia. About a hundred peoplemanage the trek every year, which takes four to six months. Even if themidocean ridge were above water and nicely graded like much of theAppalachianTrail,itwouldtake7to11yearsofsteadywalkingtocomplete.Traveling the length of the world ocean’s midocean ridge may, in some

distantcentury,beachallengeforafutureFerdinandMagellan,WilliamBeebe,JacquesPiccard,SylviaEarle,JamesCameronorRichardBranson.Butit issofarbeyondpresenthumantechnicalcapabilitiesastobealmostunimaginable—afeat many times more extraordinary than circling the globe by ship, plane,balloonorrocketordescendingtothebottomoftheseaorclimbingthetallestpeak on each of the seven continents. If it is ever accomplished on foot in apressurized suit or by submarine or via some yet-to-be-invented all-terrainseafloor vehicle, it will be an epic achievement of human endeavor, not tomentionunderwaterengineering.AswewalksouthonourimaginarytrekalongtheMid-AtlanticRidge,oneof

thefirstthingswerealizeisthattheridgeis,infact,ariftvalleylocatedalongthe topof theridge.It is theunderwaterequivalentof theGreatRiftValleyofEastAfrica.Thusourjourneyismadealittleeasierbecausewecanfollowthisriftvalley,ratherthanbumpingupanddownonsteeppeaks.Insomeplaces,theriftvalley resemblesaglassy-smoothhighway,althoughwhat seems like levelblackpavingisoftenevidenceofrecentlavaflows,fortheriftitselfstraddlesthemostactivevolcanoesintheworld.Morethan80percentoftheEarth’svolcanicactivity occurs here along the midocean ridge. Our path crosses some of thehottest, most dangerous and volatile parts of the planet—literally, the placewhereEarthpushesoutmostofthenewlavathatbecomesseafloor.Everyyear,underwatervolcanoesproducemorethanfivecubicmiles(20km3)of lava—avolume that would completely submerge both the United States and Canada

underafoot(30cm)oflava.Attimesonourwalk,wecanfeeltheheatandseethesteamescapingbeneathourfeet.Ontheplusside,itisthenewest,never-before-seenor-touchedpartofEarth,

theplacewhere theaction is,with freshseafloor rollingoutalmostbeforeoureyes.FewplaceshaveprovidedmoreinsightsintotheEarth’sworkings,insightsthatwouldleadtothediscoveryofsomeofthelastgreat“monsters”ofthedeep.Anditallstartedhere,onthemid-Atlanticportionofthemidoceanridge.

Asearlyas1912,GermangeophysicistandexplorerAlfredWegenerproposedthetheorythatthecontinentsweredrifting.Tothe19th-centuryfixeduniversefromwhichWegenerhademerged,hiswasabizarrenotion,

butitdidexplainwhytheEuropeanandAfricancontinentsappeartofittogetherwiththeAmericasandthefindingofsimilarfossilsonoppositesidesofthe

ocean.

ThelongjourneythatledtopuzzlingoutthetruenatureoftheMid-AtlanticRidgebeganwithAmericanhydrographerMatthewFontaineMaury,whomadesome200soundingsintheNorthAtlanticfromhisship, theDolphin.In1854,onhis chartof theNorthAtlantic—the first attempt at anoceanographic chartfor an entire ocean seafloor—Maury depicted an area near the center of theoceanwherethebottomwasmuchshallower thanoff thecontinentalshelf.Hecalled it the “Dolphin Rise.”On pure hunch and driven by spiritual leanings,Mauryimaginedtheareawasruggedmountains.Twodecadeslater,inthemid-1870s,SirCharlesWyvilleThomson,onboardtheHMSChallenger,producedthedetailedsoundingsoftheridgethatshoweditextendedatleastfromIcelandallthewaytoTristandaCunha,avolcanicislandintheSouthAtlanticroughlymidwaybetweenSouthAfricaandArgentina.Healsofoundevidenceofridgesinotheroceans,butnotenoughtoconceivetheideaofonecontinuousmountainridge.That ideawould emerge later, piece bypiece at first and then in a blinding

flash.The full significanceof theseunderseamountainsbecameevident in the1960s, with the modern geological revolution of plate tectonics. Thisdemonstratedtheimportanceofdevelopinganunderstandingoftheworkingsofthe ocean to be able to grasp how and why continents move, the role ofvolcanoes, the meaning of earthquakes and how Earth undergoes geologicalchange.As early as 1912, German geophysicist and explorer Alfred Wegener

proposedthetheorythatthecontinentsweredrifting.Tothe19th-centuryfixeduniversefromwhichWegenerhademerged,hiswasabizarrenotion,butitdidexplainwhytheEuropeanandAfricancontinentsappeartofittogetherwiththeAmericas and the finding of similar fossils on opposite sides of the ocean.Wegener envisioned continents as slow-moving ships plying the oceans ongeological time scales.Yet he had noway to test his hypothesis, to prove histheory.Todo thatwould require, amongother things, an accuratemappingoftheseabottomanddatingthesediments.U.S.NavyphysicistHarveyC.Hayestookthescienceofseafloormappinga

giantstepfurtherin1922whenhemadenearly1,000deep-seaechosoundingsacross theNorthAtlantic inasingleweekfromamovingship.Hissecret: theHayesSonicDepthFinder.Asinglesoundingthathadformerlytakenmostofaday using a sounding line now took about a minute. Echo soundings soonconfirmedthattheMid-AtlanticRidgewas,indeed,aruggedmountainchain.By the 1950s, seismologists had determined that the Mid-Atlantic Ridge

corresponded to a series of earthquake epicenters. American physicists BruceHeezenandMauriceEwingproposedthattheMid-AtlanticRidgerift—acanyonrecognizedonlyafterunderwater-mapmakerMarieTharpbegantoillustratethebottomtopographyfromsoundings—wasavolcanicfissurefilledregularlywithlava from the Earth’s hot mantle. The lava flowed up and out, creating newoceancrust, or seafloor, andcausing the rift togrowwider.Thekey ideawasthat thismovement at the boundaries of what are now known as the tectonicplates influences themovement of the continents situated on the plates.WhenHeezenplottedthelocationofearthquakeepicentersallovertheworld,hecouldsee thatmanyof themextended inagreat linearoundEarth.He toldTharp tokeeppaintingmountainswithriftvalleys.ThusHeezenandTharpfirstgraspedtheideaoftheworld’slongestmountain

chain—themidoceanridgeandthegreatglobalriftvalley—and“saw”thatthesemountains originated as rising lava. Still, the theory was unsupported bysufficient evidence, and some scientists regarded it as nothing more than afigmentofthepair’sactiveimaginations.Therewasnoexplanationforwhereallthisnewseafloorcrustwasgoing.Heezensuggestedthattheplanetitselfmight

be slowly expanding. Had he considered the deep ocean trenches—whereearthquakesoccur,wheredifferentkindsofvolcanoesformfromthecollidingofplates andwhere the crust is being subducted back into the Earth—hewouldhavehadclosetothewholepicture.Throughout the 1960s, the various pieces of the plate-tectonic revolution in

geology fell into place. American geologist Harry Hess combined Heezen’sobservationswithearlierfindingsaboutlowgravityindeepoceantrenchesandsuggested,in1960,thatthespreadingseafloorcrustwasbeingdrivendownwardandsubducted,orforced,intothemantlewhereplatesarecolliding,suchasinthewesternPacific.In1963,CambridgeUniversityscientistssolvedthepuzzleofthealternating

polarityfoundinthestripedpatternsofrocks(containingmagnetite)aroundthemidoceanridge.EarthhasnotalwayshadamagneticNorthPole;attimesduringourplanet’sgeologichistory, theSouthPolehasbeenmagnetic.Over thepast85millionyears, themagnetic poles have flippedmore than177 times.Therehasbeenoneswitchinthepasttwomillionyears.As the lava emerged from the midocean ridge, the magnetite in the lava

recordedthepolarityoftheday,whethernorthorsouth,beforespreadingoutoneithersideoftheridge.Theresultisamagneticrecord—apatternofmagnetizedstripes all along the seafloor,with each stripe displaying alternately north andsouthpolarityastheEarth’smagneticnorthhadswitchedtomagneticsouthandviceversa.Thepatternoneithersideoftheridgematchesperfectly.Scientists do not know why or how magnetic reversals happen, but

statistically,weareoverdueforsuchareversal.Evenwithadvancewarningandagradualtransitionperiodasalltheworld’scompassesbeginpointingsouth,acriticalaspectoftheEarth’snavigationsystemcouldbedisturbedbysomethingfar more potentially disruptive than the so-called millennium bug that hadbusinessesandgovernmentssoconcernedinthelate1990s.Thisstartlingmagneticrecordrevealedthattheseafloorisconstantlymoving.

Alongtheriftvalley,theseafloorisnewandhot,butasyoumoveeverfartheraway,itbecomesolder,colder,thickerandheavier.Piecesoftheoldestseafloorfrom the ancient seas ofTethys and Iapetus can still be foundon the seaflooraround theworld.Mostof theolder seafloor,however, is at thebottomof thetrenches,whereitwillsoonbesubducted.Butit’snotthatold.Comparedwiththecontinentalcrust,whichis,onaverage,twobillionyearsold,withsomepartsolder than fourbillionyears,mostoceanic crust is less than170millionyearsold,withameanageof100millionyears.Notmuchmorethanyesterdayinthegeologicaltimescale.Thesedimentcoverneartheridgesismuchthinnerthanitis in the trenches, though it is surprisingly thin everywhere. Because of the

constantrecyclingoftheocean’scrust,theseafloorcontainsfewfossilsfromtheJurassicperiodorearlier.Thefossilswouldbeancientonlyiftheywereupliftedwith oceanic crust to form ophiolites, the dark green igneous rock that comesfrom submarine eruptions, which is how ancient fossils were left behind inoceaniccrustintheUralsofRussia.

MoltenpillowlavaeruptsfromanunderwaterlavatubeattheoceanentrancetoHawaii’sKıˉlaueavolcano,creatingnewseafloor.Everyyear,underwatervolcanoesproducemorethanfivecubicmiles(20km3)oflava,avolumethatwouldcompletelysubmergeanareathesizeoftheUnitedStatesandCanadaunderafoot(30cm)oflava.

Thesoft-bodied,scalelessParaliparisisakindofsnailfishfoundatthebottomoftheocean—inthiscase,ontheMid-AtlanticRidgeat2,300to3,300feet(700–1,000m)down.Notethelargenumberofcephalicpores,whicharepartofthesensorycanal.Theyhelpinthedetectionofprey.Ofcourse,thelargeeyesdon'tmissmuch.

These predatory heteropod mollusks (Carinaria lamarcki) are typically foundabove the Mid-Atlantic Ridge at depths from 240 to 590 feet (74–180 m).Measuringup to 8½ inches (22 cm) long, thismolluskhas a toughgelatinousbodywith a small shell that covers its visceralmass.A large foot ismodifiedinto a fin for swimming, and it has two well-developed eyes. A flexiblecontractile proboscis ends in powerful radula in themouth,which is used forraspingitsprey.

Oneofthemorecolorfulbioluminescentjellyfishinthedeepsea,thishydromedusanjellyfish(Crossotamillsae)catchesfoodbytrailingitstentaclesacrosstheseaflooroftheMid-AtlanticRidgeatadepthof8,850feet(2,700m).

Thediscoverythatthedeepseaharborsfew“livingfossil”seamonstersandthat the spreading and subduction of the seafloor were, in effect, destroyingrecordsofancientfossilswasadisappointment.Yetscientistswouldeventuallyfind something deeply rewarding, both ancient and new, on the ocean floor,something with outstanding geological as well as biological significance thatwouldchange thewaywestudy theveryoriginof life.But first, therewereafew more pieces to be unearthed before the plate-tectonics puzzle could besolved.On our journey down the Mid-Atlantic Ridge, the rift valley alternately

widens to some20miles (32km)andnarrows to just a fewmiles.Thevalleyalso rises and falls, and the gentler parts of our trek might be compared towalking on the back of Scottish golf links. On themargins of the rift valley,however,infrontofthesteeppeaksoneitherside,thevalleyflooractuallystartsto fall away a little. This is the sensation of stepping onto a swellingmagmachamber.Insomeplaces,theriftvalleysuddenlyseemstoend.Theseoceanicfracture

zones—deeptroughscuttingthroughtheridgeatrightangles—wererevealedbyechosounding.ThemajorAtlanticfracturezonesweencounterbetweenIcelandandtheCapeVerdeIslands,offthebulgeofAfrica,carrythenamesofassortedoceanographers and other scientists, such as Charlie-Gibbs, Faraday,Maxwelland Kurchatov. Then there are Pico, Oceanographer, Hayes and Atlantis.Geometry on the surface of a sphere means that there could never be a neatlinearsystemofmountainsandriftvalleysatplateboundariescrossingfromthenorthern to the southernhemisphereor fromwest toeast. Instead, the tectonicplatesslide,jostleandstruggletofitagainstoneanother.Andsoeachtimeweencounteranoceanicfracturezone,wemustveertotherightorleftandrelocateourriftvalley—whichissometimesseveralhundredmilesaway—beforewecanresumeourround-the-worldrift-valleyexploration.The fracture zones also contain transform faults, located between the offset

segmentsoftheridge.Atransformfaultiswheretwoblocksofcrustslidealongeachotherwithoutnewcrustbeingcreated (asat the ridge)oroldcrustbeingsubducted(asinthetrenches).In1967,geophysicistsJasonMorganoftheUnitedStatesandDanMcKenzie

of Britain independently assembled the now convincing evidence for fracturezones,transformfaults,midoceanridgesandtrenchesandprovedthattheyallfittogether, putting the finishing touches on the plate-tectonics revolution. ThusAlfredWegener,whofirsthintedattheideadecadesbeforeandwasdismissed,evenridiculed,intheinterveningyears,becamethe“platetecprophet,”althoughhisignoranceoftheoceanhadpreventedhimfromextendinghisvision.

YetevenwhenWegenerfrozetodeathin1930whileexploringGreenland,hewasnotlookingtotheseafortherealclues.ThekeytounderstandingEarthwasnot a matter of continental drift so much as seafloor spreading. Yes, thecontinents are drifting, but only because they are situated on plates that areresponding to seafloor spreading in one way or another. Today, the typicalpersonon thestreetmayormaynotbelieve in terra firma, thesolidearth,butfew have an opinion about the ocean. The real Earth story lies in the ever-shifting seafloor. We live on a water planet, and no branch of Earth oratmospheric science, from geochemistry to climatology, can ignore or dismissthepredominanteffectoftheworldoceanandalltheoceanbasins.As we follow the detours of more fracture zones, we finally come to the

Azores, in the central North Atlantic, where three plates meet—the NorthAmerican, Eurasian and African. We follow the boundaries of the NorthAmerican andAfricanplates as the ridge advances steadily in a southwesterlydirection,seeminglycompensatingforthebulgeofAfricaandtosteerasteadycoursethroughthecenteroftheAtlantic.TheNorthAmericanPlategiveswayto the South American Plate northeast of South America. Thereafter, as iffollowing the receding African bulge, the Mid-Atlantic Ridge veers to thesoutheast, splitting the track betweenBrazil andSenegal, the shortest distanceacrosstheAtlantic,beforeresumingitsdue-southprogress.Morefracturezonesareencountered,andinsomeplaces, therift isdwarfed

by rocky peaks up to 10,000 feet (3,000 m) high on either side. But the riftvalley proceeds past Tristan daCunha to a point almostmidway between thesouthern tipofAfrica andAntarctica.There, theMid-AtlanticRidge ends andtheBouvetFractureZoneleadsintotheSouthwestIndianRidge.IntheAtlantic,theridgewaspredominantlynorth-southandthefracturezonesranfromeasttowest, but now the ridge proceeds in an east-northeasterly direction and thefracture zones run north to south. As we trace the border of the African andAntarctic plates, we cross six great north-south fracture zones before theSouthwestIndianRidgereachesthecenteroftheIndianOcean.Thenitabruptlyveers southeast along the Indo-Australian Plate to form the Southeast IndianRidge.ThisroundsthesoutherncoastofAustralia,bisectingtheSouthernOceanbelowNewZealandasitbecomesthePacific-AntarcticRidge,socalledbecauseitformstheriftvalleybetweenthePacificandAntarcticplates.The Pacific ridges are of an older ocean, and they look different.With an

estimatedonemillion-plusvolcanoes,thePacificbasinhasmanymorevolcaniceruptions,andtheseafloorismovingfasterherethanintheAtlantic.Some200million years ago, the Pacific originated as Panthalassa—the world oceansurroundingPangaea, thesupercontinentthat laterseparatedintothecontinents

we know today. Since the time of Panthalassa, the Pacific basin has beenshrinking, plowingmore seafloor back into themantle in the trenches than isrisingalongtheEastPacificRise.ButtheEastPacificseafloorisbeingcreatedand is spreading apart up to nine times faster than the seafloor at the Mid-Atlantic Ridge. With so many more trenches available to subduct crust, thePacific is a wilder, more dynamic place. And all this results in a differenttopography.Ironically,theresultismountainswithgentlerrises,ashallowandnarrowriftvalleyandendlesslow-lyingabyssalhills.Still,thePacifictrenchesarethesteepestanddeepestpitsintheworld.Just as the old, rounded Appalachian Mountains contrast with the steep

Rockies, the gentle slopeof theEastPacificRise—sometimesonly1,000 feet(300m)high,withariftvalleyafewhundredfeetdeepandonlyamile(1.6km)wide—makes a stark contrast to the sharp features of theMid-AtlanticRidge.That’swhyoceanographersusetheword“rise”inthePacificinsteadof“ridge,”toreflectthedifferenceinthegradualaccumulationofheight.Turningnortheastnow, in thegreatopenPacific,wefollowtheEastPacific

Rise, crossing more fracture zones, which lengthen the journey. In the SouthPacific, the ridge no longer bisects the ocean basin,which it has done to thispoint, but continues to move decidedly to the eastern portion of the SouthPacific, almost on a beeline for the Galápagos Rift, an offshoot of the EastPacificRisejustnortheastoftheGalápagosIslands.Anywhereonthisgreatjourney,wecouldhavewitnessedvolcanicactivityor

stoppedtostudythepeculiarlife-formsthatliveintherifts,yetitishere,alongthe East Pacific Rise, where the magma chambers are known to expand andexplode frequently, filling the rift along the rise. And it is here, where theseafloortemperatureisconsistentlyhigher—sometimesveryhigh—thatwemeetthesea’snewest“monsters”ofthedeep.The first clues emerged in the early 1970s, when oceanographers were

sampling thewater alongportions of theEastPacificRise.Occasionally, theyfoundhot-water“spikes”aswellasso-calledprimordialgases, suchasheliumisotopes, indicating that thewaterwasbeingheatedbymolten rockbelow theseabed. These findings provided the first inkling of the existence of deep-seahydrothermal vents, which was not surprising, since volcanic activity wassupposed to be found along the spreading centers of the midocean ridge—althoughnoonehadeverseenahotspringoradeep-seahydrothermalvent.In 1972, geologists aboard an oceanographic research vessel cruising above

theGalápagosRiftweremeasuringearthquakesontheriftwhentheybegantonoticefishdyingorfloatingdeadat thesurface.Scoopingthemupinnets, thegeologistscouldnotdeterminewhathadkilledthem,norcouldbiologistsback

onshore.Yet therewasa tantalizingclue:Thebiologists reported that thefishlived at great depth. Only later was the connection made between geologicalactivityontheridgebelowandthepresenceofanimals.Then,in1976,oceanographersusinganunderwaterinstrumentsystemcalled

“DeepTow”photographedsomelargewhiteclamsontheGalápagosRift.Onescientist half joked that they were probably thrown over the side after aclambake.Therewassimplynothoughtthatlifecouldbethrivingaroundtheseridges.Evenfishthatwanderedtooclosehadobviouslydied.Notonlywasittoohotandtoodeep,butitwastoofarfromsunlight.

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Thistubeworm,orpolychaete,wasfoundamongthecoralrubbleonacoralseamountneartheDragonVentFieldontheSouthwestIndianRidgeintheIndianOcean.

I

CreaturesintheSulfurGarden

N1977,AFTERSEVERALyearsofplanningandfund-raising,ateamofabout a dozen American geologists desperate to see “hot springs” on amidoceanridgesecuredtimeaboardtheU.S.DeepSubmergenceResearch

vehicle Alvin to explore the Galápagos Rift. The legendaryAlvin is a three-personsubmarine25feet(7.6m)longandweighing16tons(14,500kg).Whenitisnotdivingforuptoeighthoursatdepthsofupto2.8miles(4.5km),Alvinresides at the Woods Hole Oceanographic Institution in Massachusetts. Itremainsoneofthefewmannedsubmarinesavailabletodayforscientificworkinthedeepsea.Besidesitsscientificresearchmandate,Alvinwasthelittlewhitesubwiththe

redconningtowerthatsavedtheworld—or,moreaccurately,savedfacefortheUnitedStates. In themid-1960s,Alvin locatedahydrogenbomb thathadbeenlostfollowingthecrashofaU.S.AirForceB-52offthecoastofSpain.ItwasthefirstsubmarinetodiveontheRMSTitanic,anditclearlyplayedabigroleininspiringJamesCamerontobuildtheDeepseaChallengerthatwouldallowhislater,muchdeeperexplorationstothebottomoftheMarianaTrench.Therewerealso a fewmishaps overAlvin’s 36-year career. In 1968, it sank—fortunatelywithout any casualties—and spent nearly a year on the bottom, onemile (1.6km)beneaththesurface.AndAlvinwasonceattackedbya250-pound(113kg)swordfish,whose“sword”becamewedgedbetweenthejointoftwoouterplates,fixingthefishtothesublikeatrophymountedbackwards.Shortlyafter,whenAlvin’salarmsystemrevealedthattherewereleaks,thesubracedtothesurface.Theleaks,asitturnedout,wereunrelatedtotheswordfishattack.

Tubeworms(Riftiasp.)andmussels(Bathymodiolussp.)thriveinthecrevicesofthehydrothermalventsintheeasternPacific,wherethewatersaredensewithmarinesnowcarryingsulfide-dependentbacteria.Thesebacteriaprovideasourceofnutritiontoventanimals,buttubewormsdigestbacterialivinginside

them.

Builtin1964andbasedattheWoodsHoleOceanographicInstitution,Alvinbecamethefirstmannedsubmarinetoexplorethehydrothermalvents.Itcancarryuptothreepeople,hasanoperationaldepthrangeof2.8miles(4.5km)andcanspenduptoeighthoursunderwater.AlvinrecoveredahydrogenbomblostoffthecoastofSpaininthemid-1960sandwasthefirsttoexplorethewreckoftheRMSTitanic.Everythreetofiveyears,thesubisdisassembled,andmanypartsarereplaced.

Alvin’shydraulicallypoweredroboticarmsprobetubewormsatthehydrothermalventsalongtheEastPacificRise.

The current Alvin has been repaired and refitted so many times that theoriginalpartsaregone,butthedesignandmodelremain,asdoesthelittlesub’sgrowing list of accomplishments. None, however, can surpass the rawexcitement generated by the findingsmade on the first dive to theGalápagosRift, some 200miles (320 km) northeast of theGalápagos Islands, inAugust1977.American geologist Jack Corliss (then at Oregon State University, now at

CentralEuropeanUniversity,Budapest)andJohnEdmond,aScotsgeochemistbasedat theMassachusetts InstituteofTechnology,wereon that firstdive.Astheywerecruisingalongtherift,about1½miles(2.4km)down,theireyeswideopen,thepilotsuddenlynoticedawhitecrabontheseafloor.Astheyhadseenalmostno life inanarea thatCorlissdescribedas smoothandglassy, itwasasurprising sight. Shortly thereafter, thewater began to turnmilky and cloudy,andCorlissnoticedthathisspeciallyadaptedunderwaterthermometerbegantoindicateasteadyriseintemperature.Thealarmonthedevicewentoff,signalinganevenhighertemperature.Andthenthepilotannouncedexcitedly,“Thereareclamsouthere!”AsAlvindrewnearer,CorlissandEdmondweretreatedtotheirfirstglimpse

of the “Rose Garden,” a strange oasis in this submarine desert, as they laterdescribedit.Theyhadfoundthehotsprings,thehydrothermalvents,andtherewaslifeeverywhere:clams,mussels,tubewormsandmore.Andthesewerenotjustanyclamsbutghostlywhite,giantfoot-long(30cm)clams,aswellassix-inch (15 cm) mussels. Waving in the currents all around them were denselypackedsnakeliketubewormsupto3½feet(1m)long.Theywereattacheddeepwithin thecrevicesand sported red flower-bud-like tips.The lights fromAlvinilluminatedanduncoveredthisovergrowndeep-seagardeninallitswonder.Corliss and Edmond’s first thought on seeing the bizarre, monstrous-sized

creatureswasthattheyhadstumbleduponaprimordialecosystemfarremovedfrom time and certainly never before seen by humans. Perhaps it dated backmillionsofyears tosomelostworld.As thenewshit thescientificcommunitythrough Nature, Science, New Scientist and The New York Times, the buzzechoed the excitement generated up to a hundred years earlier by the deep-ocean, living-fossil search.But thesewerenot fossils, livingorotherwise.Thetubeworms and most of the other dominant animals were probably recent inorigin—less than100millionyearsold.Theywereyoungandalive. ItprovedthatthereareamazingsecretsoftheEarth’sbiologicalandgeologicalhistorytobefoundindistinctcorners,ridgesandtrenchesoftheworldocean.Theprocessof revealing themwould cast vital light onmarine biology,microbiology andvarious subdisciplines of earth science. The textbooks would have to be

rewritten.Life at the hydrothermal vents appeared to bend all the previous rules. The

animals herewere not slow-growing, asweremost of the deep-sea fauna, butfast-growing, fueled by some extraordinary energy source.While Corliss andEdmondsensedthis,theyhadnoideahowtheseanimalscouldthrive.At50to68 degrees F (10–20°C), the water was warm compared with the 36-to 39-degree-F(2–4°C)temperatureofmostofthedeepsea.Andamazingly,thewaterwas loaded with toxic hydrogen sulfide.Alvin gathered a few samples of thetubeworms and mollusks for biologists onshore, and the basic story soonemerged.WhatCorlissandEdmondhadfoundwasthefirstecosystemonEarththat didn’t get its energy from the sun, from photosynthesis. The basis of thefoodwebwasnotphotosyntheticorganisms.Butwhatwasit?When biologists began to dissect the giant tubeworms—creatures with no

mouthsordigestive systems—theyexperiencedanoverpowering stench.Morethan one researcher found that the foul odor could clear the lab of all thoseuninitiated to the deep, allowing for hours of undisturbed study. In fact, thetubewormswerefullofbacteriathattheywere,ineffect,feedingon.Theclamsand mussels had bacteria in their tissues too. Other animals at the vent alsoappearedtobelivingwith,orpossiblyon,bacteria,filteringthemicroorganismsfromthewaterorgrazingonthebacterialfilmontherocks.In theearly1980s,graduatestudentColleenCavanaugh,nowaprofessorof

biology at HarvardUniversity, first proposed that the giant tubeworms obtaintheir food from bacteria living within their cells. Through a process calledchemosynthesis, the bacteria transform methane and sulfur, among otherinedibles, intoorganicmoleculesuponwhich the tubeworms feed.Around thesame time,HolgerW. Jannasch of theWoodsHoleOceanographic Institutionand David Karl of the University of Hawaii at Manoa were looking at ventbacteria.Theywereable to showexperimentally that thesebacteriadependonhydrogensulfideandotherformsofsulfur,thusrevealingthevitallinkbetweenthe bacteria and the sulfur at the vents. Scientists began to realize that thesebacteria support an entire hydrothermal ecosystem. Instead of photosyntheticphytoplankton,theseso-calledchemosyntheticbacteriaprovedtobetheorganicbasisofthefoodwebinthehydrothermal-ventcommunity.Thehydrothermalventsstandasoneofthegreatdiscoveriesofthelate20th

century.Theearly reports trumpetedbacteria livingat 480degreesF (250°C),tubeworms belonging not only to new species but to new phyla and thedependenceof theecosystemonchemosynthesis.Infact, themaximumknowntemperaturehabitat for amicroorganism is about240degreesF (115°C),withtheoretical limits of up to 300 degrees F (150°C), but the hottest vent

temperature has recently beenmeasured at 765 degrees F (407°C). The gianttubeworms,bizarreandunclassifiableastheyfirstseemed,haveprovedtobeakindofannelidworm.Todate,despiteearlyindicationsofpossiblenewphyla,none have been confirmed from the vents. Finally, the dependence onchemosynthesisismorecomplicatedthanfirstenvisioned.Ventanimalsalsoneed thesunandphotosynthesis.Thevarious tubeworms,

clams,musselsandotherventanimalsareaerobic;thatis,theyneedoxygen,asdo all large multicellular organisms. The oxygen they obtain from seawatercomesfromphotosynthesis.Further,even though theorganicbasisof thefoodwebischemosynthesis,orchemosyntheticbacteria,thechemicalenergyusedbythebacteriacomesfromoxidationofsulfide.Still,strangespecieswerefoundatthehydrothermalvents,livinginanewtypeofecosystem.At first, the discovery of the unlikely hydrothermal-vent ecosystem was

thoughttobearareoccurrence.Weretheremoreventsouttherewiththesameordifferentanimals? In thewakeofAlvin’s1977success,newexpeditionssetout to search all along thevolcanicmidocean ridgewhere tectonicplatesmet,firstintheNorthPacificandthenintheNorthAtlanticandIndianoceans.Alvinwasindemandnowmorethaneverbefore.Scientistsandtechniciansscrambledfor shipandsubmarine time,andmanywereprepared to spendChristmasandotherholidaysatsea.Ashardasitwasforabiologisttobeawayfromfriendsand lovedonesat such times,beingonAlvinor the supportingship,gatheringsamples of strange newworms,mussels and shrimp, not tomention bacterialmicrobes,wasafairsubstitutefortraditionalcelebrations.

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Deep-seaventshrimp(Rimicarissp.)werediscoveredintheDragonVentFieldintheIndianOceaninNovember2011.Livingsymbioticallyintheirgillchambersarebacteriathoughttoprovidefoodfortheshrimpeitherdirectlyorthroughtheirwasteproducts.Thebacterialikethehottemperatures.

R

FartherAlongtheRidgeandBackinTime

ESUMINGOURjourneyalong theworld’s longestmountain range,we follow the East Pacific Rise north of the equator and theGalápagos Islands as it heads toward Mexico. This portion of the

midocean ridge is prime country for hydrothermal vents. In 1979, scientistsdiscoverednewhydrothermalvents1,800miles(2,900km)northalongtheridgeinMexicanwaters, near themouth of theGulf ofCalifornia.After seeing thewidely publicized photographs of the Rose Garden on the Galápagos Rift,scientists were surprised at how different these vents looked. Here, toweringchimneylike structures, nowknown as “black smokers,” spewedout clouds ofsuperheatedwaterladenwithchemicalsattemperaturesoftypically660degreesF (350°C)—750degreesF (400°C)or higher following an eruption.As at theGalápagosRift,coldseawaterflowedintocracksintheoceanrift,whereitmethot basaltic lava and became superheated, picking up sulfur, iron, copper andzinc.Buttheblacksmokerswerenewer,superhotvents.Asthishotwatermergeswiththecoldoceanwaterat36degreesF(2°C),the

mineralsinthehotwaterprecipitateintochimneylikestructures,someofwhichgrowattherateofupto12inches(30cm)perday.Thehotwaterandchemicalspouring out of these structures are rich in copper sulfides, and as the sulfidedepositsprecipitate,thewaterturnsblack,givingtheappearanceofblacksmokerisingfromachimney.Hencethenameblacksmokers.Scientistssaythatamere30blacksmokerscangeneratethesameenergyper

hourasthatproducedbyalargenuclear-powerreactor.Every10millionyears,avolumeof seawater equal to that of theworld ocean passes through the blacksmokers and vents on themidocean ridge.Thus the chemistry of the ocean isprofoundlyinfluencedbythechemicalspouringoutoftheblacksmokers.

Thefullfloweringofahydrothermalventproducesabundanttubeworms(Riftiasp.)upto3½feet(1m)long.Grazingamongthefleshytubewormsarebrachyurancrabsandapinkisheelpout,amemberoftheZoarcidaefamily.

In2012,theWoodsHoleOceanographicInstitution’sremotelyoperatedvehicleJasonprobedtheexplosionoflifealonganunderwatermountainchainknownastheMid-CaymanRise,atthePiccardVentFieldintheCaribbeanSea.Atmorethanthreemiles(5km)deepandcoveredinanemonesandshrimp,thePiccardventshaveprovedtobethedeepestknownhydrothermalventsintheworld.

Alivingmassofventshrimpswarmsaroundahydrothermal-ventfield.AstheheatandmineralspourforthfromEarth,lifeherecanbecomesodenselypopulatedthattheventopeningsandrocksareobscuredfromview.

The sight of black smokers looming out of the inky darkness transforms asubmarine cruise into a surreal experience, and the researchers had to keepremindingthemselvesthatthestructureswerenotalive,norweretheymonsters.Infact,noclams,musselsortubewormswerefoundontheblacksmokers—thesmokersaretoohot—butashortdistanceaway,therewaslife.Thetemperatureinsideablacksmokercomparedwiththetemperatureafewfeetawaycandifferby more than 750 Fahrenheit degrees (416 Celsius degrees), the greatesttemperaturedifferentialanywhereonEarthacrossthisshortadistance.Whereelsecouldoneevenfindsuchhottemperatures?Atthesurface,water

boilsat212degreesF(100°C),butasthepressureincreasesatdepthfrom1to218atmospheres,theboilingpointalsorises,toamaximumcriticaltemperatureof 705 degrees F (374°C). In the deep sea at 1½ miles (2.4 km) down, thisprevents the water from boiling, allowing it to become superheated instead.Insulatedbysomuchcoldwateraroundthehotwater,however,Alvinwasableto travel among the black smokers, probing and studying in relative safety,barringafull-scalevolcaniceruption.Manymorehydrothermalvents,aswellas lushoases,havebeendiscovered

ontheoceanbottomsince1979.ScientistshaveassignedthemnameslikeClamAcresandHole-to-Hell.Mostofthesehydrothermal-ventsitesareinthePacific,butin1985,twositeswerefoundalongtheMid-AtlanticRidgeatTAG(Trans-AtlanticGeotraverse) and Snake Pit. Twomorewere found in 1992 at LuckyStrike and Broken Spur. The vent animals in the Atlantic differ considerablyfromthoseinthePacific.Inplaceofthegiant tubewormsandclams, therearemoremussels,whiteeel-likefishandshrimpwithhighlymodifiedeyesontheirbacksthatcandetectdimsourcesoflight.Andthereareblacksmokersheretoo.In 1988, some surprising findings were made in the deep trenches, or

subduction zones, of thewestern Pacific, notably in the JapanTrench and theMariana Trough, near theMariana Trench.Hot springswere discovered thereandplentyoflife.Themostconspicuousresidentsfoundwereanewfamilyofsnails—the first ever snails with chemosynthetic bacteria in their gills. Otherunusual species were recorded too, but about half were members of generaalreadyknownfrom the ridges in theeasternPacific, some5,000miles (8,050km)away.So thereweredeep-sea“monsters”allalong—peoplehad justbeenlookingforthewrongkindsofmonsters.Insteadofmonstrositieswithtwoheadsor giant mouths and stomachs the size of school buses, even more bizarrecreatures reside in the deep—animalswith nomouths and no anuses, animalsthatarefueledbybacteriaanddon’trelyentirelyonthesun.Hydrothermal vents have been described as oases in the desert. The deep

seafloorandmidoceanridgesarenotdevoidoflife(andneitheraredeserts),but

the vents are so richwith spectacular biomass that the contrastmakes such acomparisoninevitable.As scientists discover additional hydrothermal vents and return to known

sites, theyhavebeguntorecord the lifehistoryofahydrothermalvent.Likeatropical rainforest, a savannaoranyothercommunityofplantsandanimals, ahydrothermalventhasitsowncycle.Andtounderstandthestrangeanimalsthatlivehere, it isnecessary to followahydrothermalvent frombirth through fullfloweringtodeath.

Aburningquestionis:Howdovent-communityanimalswithsuchdistinctivelifestylespassontheirgenesand

managetoturnupagainwhenthenextventopportunityarisessomemilesaway?

The birth of a hydrothermal vent is a cataclysmic event in which largeamountsofheatandmineralsarebelchedfromthecenterof theEarth.Withinhours or days, the chemosynthetic bacteria and the various animals begin toappear, although where they come from is still a matter of conjecture, eachfinding its preferred niche between the extremes of cold seawater and the hotchimney and, most important, fixing its position “chemically.” The animalsgrow rapidly, with the clams reaching full size in four to six years, buteventually, theventbegins to turndormant, and the steady sourceofnutrientsforthechemosyntheticbacteriadriesup.Since the various clams, tubeworms andmussels cannotmoveon, theydie.

Finally, the last signs of a vent site are often pieces of clamshells and burnt,brokenworms that resemble the remnantsof amidden site, the last clambake.By dating the shells and other materials from the vent sites, scientists haveestimatedthatthelifecycleofadeepwater-ventcommunityontheEastPacificRise ison theorderof severaldecades.This isveryshortcomparedwithventfieldsontheMid-AtlanticRidge,someofwhicharethoughttobehundredstothousands of years old, equivalent to time scales for certain land-based forestcycles.Withinseveraldecades,aventsiteinthePacificcouldgofromvirtuallynolifetobecoming,atitspeak,oneofthedensestassemblagesoflife,withthehighest biomass (weight of living things per unit area) onEarth, then back to

littleornothingagain.Ofthemorethan700speciesofventlifediscoveredsofar,thelifecyclesof

only a handful of highly specialized species have been observed. A burningquestion is: How do vent-community animals with such distinctive lifestylespassontheirgenesandmanagetoturnupagainwhenthenextventopportunityarises some miles away? In active areas, particularly in the Pacific, thehydrothermal vents and gardens may occur as frequently as everymile or soalongthemidoceanridge;theAtlanticappearstohavefewerventsandgardens.Butintheslow-movingdeepsea,evenamilecanbeaformidabledistance.Mostventanimalsreproduce,freelysheddinglargenumbersofgametes(eggs

orsperm)intothewatercolumn.Here,thegametesmeet,theeggsgetfertilizedandtheembryosdevelopintodriftinglarvae.Thiszooplanktonapparentlyexistsinsufficientnumbers,survives longenoughand travelsoncurrents farenoughthatthespeciesitselfsurvives.Perhapsthecurrentsthatsometimesrunalongthebottomoftheriftvalleyscarrylarvaetothenewestpotentialsites.Buthowdothey travel for miles and miles? According to American hydrothermal-ventbiologist Cindy Lee Van Dover, the present thinking is that long-distancedispersal does take place, but it is probably on the order of a fewmiles, notthousandsofmiles.“Wethinkthepopulationsmoveaboutfollowingastepping-stonemodel,” she says, “with larvae reaching some ‘distant’ site, reproducingand then sending their propagules one step farther and so progressing a longdistance over generations, rather than within a single generation.” There hasbeen a suggestion that carcasses fromwhales dying at sea and sinking to theseafloormayfunctionpartlyasstepping-stonesbetweenvents.Thisexplanationmightapplytoafewlarvalspecies,butmostoftheseenvironmentsshareonlyasubsetofspecies.Awhalecarcasswouldalsoformitsownmini-ecosystemthatcould support unique species. Whatever the strategies for dispersal, theextraordinaryfact is thatasoneventdiesalong themidoceanridge,another isseeminglyborn,andnewlifeappearsrapidlyafterthehotspringsdevelop.

♦

Restingonthebottomoftheseaatdepthsof3,300to8,200feet(1,000–2,500m),withitsheadslightlyraised,thedeep-sealizardfish(Bathysaurusferox)waitsforitsfishordecapodprey,deadoralive,todriftwithinreach.Itscoloringcanbebrown,blackornearlywhite,anditssuccessatpredationmaydependon

beingabletoblendinwiththeoceanfloor.

Thisdeep-seasquatlobster,orgalatheidcrab,foundcrawlingonacoralseamountintheIndianOceaninDecember2011,hasunusuallylongarms.Thesecrustaceanshavealsobeenobservedinlargenumbersaroundhydrothermalvents.ItisyettobeconfirmedwhetherthisspeciesisfromthegenusGalatheaorMurida.

A

BlackSmokersandNewLife-Forms

T THE NORTHERN end of the Gulf of California, the midoceanridgecomesashoreonthewesternNorthAmericancontinent.Asidefromislandsthatrangeinsizefromtinyvolcanicislets totheisland

ofIceland,it istheonlytimethemidoceanridgemeetsamajorlandmass.Theresults arewidelyknown,discussed and feared.For the ridge extendshalf thelengthofCalifornia,alongthefamousSanAndreasFault,beforeitmovesouttoseaagainoffMendocino.Fromthisperspective, it iseasy toseewhyaspreadingmidoceanridge, the

boundary of two plates meeting or, rather, diverging in California, has thepotential to cause some problems. In fact, over geological time, the problemswill get a great deal worse before they get better. On the California coast,everythingwestofthefaultlineisitselfheadingwest.TheoceanwilleventuallyspillinfromtheGulfofCalifornia,creatinghavoconascalethathomeownerswho worry about losing a foot of property every few years have yet toappreciate.Inotherwords,westernCaliforniaisbecominganisland.Ofcourse,Iceland,on theMid-AtlanticRidge, isalsosplitting in two,but slowlyenoughthatvolcanicactivityrepairstherift.InthePacific,theplatesaremovingapartthreetimesfaster.Atsomefuturedate,thisnewislandstateoftheUnitedStatesmightbecalled“IslaL.A.”(IslandoftheLostAngels)afterits largestcity,nodoubttobelinkedtothemainlandbyever-lengtheningbridges.Backouttosea,nearMendocino,ourfinaldeep-seastopistheJuandeFuca

Ridge. The hydrothermal vents on this part of the midocean ridge werediscoveredbeginningin1983,andtheareahasbeenpopularwithAmericanandCanadianscientificresearchersbecauseofitsrelativeproximitytothewestcoastofNorthAmerica.Whenthelargestblacksmokerintheworldwasfoundherein1991,thenotorietyoftheJuandeFucaRidgewasfixed.Thesizeofa13-storybuilding, it measured 148 feet (45 m) tall and a massive 40 feet (12 m) indiameter.ItisnosurprisethatscientistscalleditGodzilla.

Blacksmokersformwhencoldseawaterflowsintoseafloorcracksandmeetshotbasalticlava.Carryingelementsofsulfur,iron,copperandzinc,thesuperheatedwateremergesfromtheseafloorandprecipitatesintochimneylikestructuresthatcangrowattherateofafoot(30cm)perday,surpassingsixfeet(2m)inaweek.

Ghostlywhiteshrimpandanemonestrytomakealivingoncoolingblacksmokers.Hottestwhenitfirstforms,ablacksmokereventuallybeginstocool.Evenso,itisextraordinarilyhot.Thetemperatureinsideablacksmokercanbeupto750Fahrenheitdegrees(416Celsiusdegrees)higherthanthatofthewaterjustafewfeetaway.ThisisthegreatesttemperaturedifferentialanywhereonEarthacrossashortdistance.

Superheatedwaterinachemicalcoppersulfide“soup”—typically660degreesF(350°C)—billowsoutofblacksmokers.Asthesulfidedepositsprecipitate,thewaterturnsblack,lookinglikeblacksmokeemanatingfromafireintheEarth’scrust.Infact,thereisneithersmokenorfire.Still,30blacksmokersarecapableofgeneratingthesameenergyperhourasthatproducedbyalargenuclear-powerreactor.

In the late 1990s, geologists and biologists in various disciplines workedtogethertoplotanassaultontheblacksmokersoftheJuandeFucaRidge.Theirgoalwastosnagafewsmokersandbringthembacktotheshipboardlab,“aliveandsmoking.”OneofthoseleadingtheeffortwasJohnDelaney,atall,beardedmarine geologist at the University of Washington, in Seattle. On a well-documentedexpeditionaboardtheThomasG.ThompsonandtheJohnP.Tullyinthesummerof1998,theteamsetoutonthe180-mile(290km)journeytothehigh-rise vents. Delaney was accompanied by, among others, John Baross, aUniversity of Washington microbiologist interested in the building-blockconditionsoflife.The precise destination was the Mothra Vent Field of the northernmost

EndeavorSegmentoftheJuandeFucaRidge.Theteamhadbeenthereseveraltimesinpreviousyears,andDelaneyhadhelpedmaketheareaoneofthebest-mapped pieces of seafloor in the world. They knew exactly where the blacksmokerswere;theyhadevenwhimsicallynamedsomeofthemforScottishfairyspirits.Providedthestructureshadnotgonecoldandtoppledoverintheinterim,theywouldbe standing there,waiting. Journalistshadcomealongon someofthe earlier expeditions. This time, however, the team was accompanied by aBBCfilmcrewthatwaspreparingaspecialdocumentaryonthe“volcanoesofthe deep” with American public television WGBH/Nova. The AmericanMuseumofNaturalHistorywascosponsoringtheexpedition,partlyinhopesofobtainingarealblacksmokertodisplayinitsHallofPlanetEarth.Afteryearsofplanning and a considerable funding investment, the scientists and filmmakerswereeagerforsuccess.As with so much deep-sea work, the success of the biology depends on

thoughtful engineering. In this case, the challengewashow to sever anup-to-750-degree-F(400°C)pieceofheavyyetsurprisinglyfragilerock,secureittoagrapplingdeviceandraiseit1½miles(2.4km)throughthewatercolumnbeforeattempting themost awkward and difficult step of all: lifting it at fullweightfromthewateranddepositingitonthedeckoftheboat.Orchestrating this engineering feat was the responsibility of LeRoy Olson.

Fourblacksmokerswouldbecutdownwithchainsawsmodifiedforunderwateruse.ButOlson’smain jobwas to scale backDelaney’s expectations.At first,Delaneywanted20-foot-high(6m)smokers.HardlyGodzilla,butwhenOlsondid the calculations, he realized thatDelaney’smini-monstersmightweigh60tons(54,430kg)each.Delaneywaspersuadedtogofor10-to14-foot(3–4m)smokers—stillaformidablechallenge.To manage the hard and delicate work of cutting down the smokers and

securing thembefore hauling them to the surface,Delaney and his colleagues

used a Canadian remotely operated vehicle named ROPOS. On the first day,however, thechain sawscouldn’tpenetrate theold smoker theyhadchosen totest their technique.Then camebadweather, duringwhich itwas too risky tolaunch the equipment or to try to pull up anything.After three days of roughseas,conditionsfinallyimproved.SendingROPOStothebottom,Olsonandhisteamtriedtoretrieveanactivechimneytheyhaddubbed“Phang.”Itbrokeintopieces.Theycontinuedtoattempttosecureatleastasectionofit.Thistime,thechainsawsandthegrapplingdeviceworked.Afteranhourandahalfofdelicatemaneuvering, Phangwas brought to the surface,with the top portionmissing.Whenitwasloweredtothedeck,itbrokeintothreeparts.Nevertheless,itwasabeginning.Thescientistsgatheredaroundthesternoftheship,pleasedwiththeirfirsttrophy,despitethefactthatitwasinpieces.Unfortunately, Phang turned out to be a dead smoker. It contained no

microbes,nolifeatall.Still,itwasvaluableforthegeologists,anditmadetheprospectofraisingtheotherthreesmokerstheyhopedtobringhomethatmuchmorerealistic.After twomore days of equipment trouble,Olson andDelaney argued over

themeritsof thechainsawversussimplyattachingaharnesstothenextblacksmoker,“Roane,”andpulling,inthehopesthatitwouldbreakoffbeforethelinesnappedor thewinchcollapsed.Since theexpeditionwas runningoutof time,theydecidedtotryDelaney’ssuggestion.Withastraining12,000pounds(5,550kg) of tension on the line, engineer Olson agreed to go up to 20,000 pounds(9,100kg),butnomore.Justwhentheywereabouttogiveupandcuttheline,theblacksmokerbrokefree.Roanecameup in twosmallpieces,but itwas“alive”andfullofmicrobes.

The internal temperaturewas 380 degrees F (194°C), a little cool for a blacksmokerandthusasignalthatitwashalfalive.Apessimistmighthavesaid“halfdead,”butitwasthefirstchimneytobebroughtupwithlifeinitscoolerparts—magicmicrobes forBaross and his students.At last, themicrobiologistswereable to get down to work, and they raced against time as the smoker rapidlycooleditsheelsontheopendeckoftheship.Theirsubjectprovidedastunningfirstglimpseoflivingbacteriainsidea“fresh”hotsmoker.On thenextand lastdayof the recoveryportionof theexpedition, the team

managed topullup twoevenhotterblack smokers. “Finn” fell apart as itwasliftedfromthewatertothedeck,but“Gwenen”remainedintact,althoughalittleon the small side, at 4½ feet (1.4m) tall. Still, thiswashot, fresh life. Itwasevenabitgooeyinside.Thegooprovedtobechalcopyrite,acopper-ironsulfidematerial.An exuberant Baross commented to the filmmakers: “The one thing you

always think about when you go into these environments is that you arepotentially going to make a new discovery on this cruise or on this dive. Itsomehowwouldneversurprisemetoseesomething,ananimal,thatwe’veneverseenbeforeorthatwethoughtwasextincttensofbillionsofyearsago.”Baross paused for an instant on theword “billions,” and you could see the

wheels turning inhishead—tensofmillionswasnotquite right,while tensofbillions would be off the scale. He went ahead and said “tens of billions,”knowingthatEarth itselfhadformedless than5billionyearsagoand that lifebegananestimated3.5billiontoperhaps4billionyearsago.ButtheAmericanpenchant for hyperbolemade the salient point: Thiswas exciting stuff. Thesemicrobeswouldprovideextraordinaryresearchmaterialsandnumerousprojectswell into the 21st century. They would be the essential pieces for the modelmicro-smokerthatBarosswouldbuildinhislabattheUniversityofWashingtontostudytheconditionsthatprobablycreatedlife.TheBBCandNovahadafilmin thecan.TheAmericanMuseumofNaturalHistoryhad itsprize too—albeitnot quite as big a prize as it had anticipated.Nonetheless, itwas a real blacksmoker.

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A

LifeAmongtheArchaeans

T THEEND of our imaginary 46,000-mile (74,000 km)midocean-ridge journeyalong themountainsof theworldocean, theEarthweonceknewhasbecomeasignificantlysmallerplace.Yetthereisstill

so much to be revealed and understood. Scientists estimate that as little as 1percent of the world-ocean floor has been mapped. John Delaney and otherresearchershavebeenworkingtodevelopanext-generationarrayofinstrumentsand to plan the infrastructure for a global collaboration to set up long-termmonitoring and studies of the deep ocean.Themidocean ridge, aswell as thedeepest trenches, will be the site of considerable future work through thiscenturyandbeyond.Harvard’sEdwardO.Wilson,whohasenthusedabouttheextraordinarydiscoveriesofspeciesdiversityinthedeepocean,hassaidthatifhewerestartinghiscareerasabiologisttoday,hewouldstudythenewfrontierofmicrobes—toparaphraseWilson,thelittlestuffthatreallyrunstheworld.ThemostexcitingexpeditionsonPlanetEarthforscientistsarenowthesearchesanddiscoveriesofsomeofthetiniestorganisms.What exactly are these microbes? “Microbes” and “microorganisms” are

termsused todescribecreaturessosmall that theycannotbeseen individuallywithoutamicroscope.Theyaresingle-cellorganisms,millionsofwhichgroupedtogether could pass through the eye of a needle. In fact, more microbes arepresentonaperson’shand than therearehumansonEarth.Withoutmicrobes,plantscouldn’tgrow,garbagewouldn’tdecay,wecouldn’tdigestourfood,andlifeasweknowitonthisplanetwouldbeimpossible.Mostofthecommonmicrobesweknowarebacteria,butmicrobesarenotjust

bacteria. At the vents, wemay discovermore forms ofmicroorganisms, eachwithitsownstory.Andsotheage-oldsearchformonstersof thedeepseahasled,bya longandcircuitous route, to thisquest formicrobesand to thatmostfundamentalofallpilgrimages:thesearchfortheoriginoflifeitself.MicrobesrepresenttheoldestformoflifeonEarth.Thereisthetantalizingpossibilitythat

someof themicrobesbeing studied todaymayyet retain thecharacteristicsoftheearliestlife-forms.Todate,microbefossilscanbedatedbackmorethan3.5billionyears,toatimelongbeforetheeraofthedinosaursandfloweringplants,whenEarthhadoceansthatsometimesreachedtheboilingpoint.AccordingtoBaross,thereisagoodchancethatmicrobiologistsmayfindmicrobeswithsomeof the samegenetic characteristics as thoseof the first lifeonEarth.Studyingthemmayprovideinsightsintotheearlyhistoryofourwaterplanet.Barosscallsit the search for “genetic fossils.” Of course, there are potential economicpayoffs,too,thatdrivethescientificeffort.So-calledmicrobeprospectingisthesearch for exotic enzymes that can survive high temperatures or high-aciditylevelsorhavedevelopednewwaysofmakingenergy.SaysBaross:“It’sawholeworldofnewmicroorganisms.”

“Seastraw,”cellsofphotosyntheticcyanobacteria(Trichodesmiumsp.),formfilamentscalledtrichomesthatstaytogetherintheroughly0.08-inch(2mm)coloniesseenhere.WoodsHoleOceanographicInstitutionresearchersfound

thatcyanobacteriacolonieshelpphytoplanktongrowbyfertilizinglow-nutrientareasoftheoceanwithnitrogen.

Inmanyways,thehottestfindatthedeep-seaventshasbeentheunmaskingofoneparticularmicrobecalledarchaea.Itisnotabacterium,althoughscientistsoriginally took it for one. At first, it was considered an “archaebacterium.”Americanmicrobiologist andbiophysicistCarlR.Woese first championed theuniquenessofthislife-formbeginningwithhisworkin1977andculminatinginaproposalin1990foranewclassificationschemeforalloflife.Archaeansareperhaps unassumingmonsters, but scientists nowmostly agree that they are adistinctlineageoflifeonEarth.Humanslastrecognizedatotallynewbranchoflifeinthe19thandearly-20th

centuries, when the conventional division of living organisms into animals orplants began to expand to three, four and, finally, five kingdoms toaccommodate fungi, bacteria and protists, which include the algae, amoebas,slimemoldsandprotozoa.Until the end of the 20th century, alongwith the common use of the five-

kingdom scheme, scientists divided life into just two overall domains: theeukaryotes (animals, plants, fungi and certain unicellular organisms, such asparamecia)andtheprokaryotes(alltheremainingmicrobes).Underthissystem,thearchaeanswere lumped into theprokaryotesalongwithbacteria.However,Woese’s proposal, now widely accepted and increasingly verified, elevatedarchaeans to a new status: a third domain of life. Under the new system, thethreebranchesaretheEukarya,BacteriaandArchaea.To put it another way, archaeans are as different from bacteria, both

geneticallyandbiochemically, as theyare fromelephants—orhumans for thatmatter.Andso,justbeforethedawnofthe21stcentury,humanshadsuddenlystumbleduponatotallyunknownlife-formatthebottomoftheseaandinotherextreme hot, cold, pH and salty environments. The archaeans thus took theirplacealongsidemightybacteriaandtherestoflifeonEarth.Therightfulplaceof this new life-formwas confirmed by the sequencing of the genome for anarchaean foundathydrothermalvents in thePacific.ThearchaeanwasnamedMethanococcusjannaschii,forthelateHolgerW.JannaschoftheWoodsHoleOceanographicInstitution,thescientistwhofirstisolatedthechemosynthetic—vent microorganisms and realized that they were special. This was the

ultimatescientifichonor—tohave the firstsequencedstrainofanentirelynewbranchoflifenamedafteryou.Archaeanshavebeendubbed“life’sextremists,”or“extremophiles”(literally,

lovers of the extreme). From the start, they kept turning up in hard-luckenvironments, including hot springs, geysers, oil wells, frozen polar seas andhighly alkaline, acidic or saltywater conditions inwhich fewother organismscouldsurvive.Archaeansnotonlysurvivebutthriveattemperatureshigherthan

anyotherknownorganismcantolerate.Thecurrentrecordhightemperatureforan archaean environment is a cool 252 degrees F (122°C).Nor are archaeansbotheredbyhighlevelsofradioactivity.Yet theycanalsoliveunder“normal”conditions among the drifters, part of the plankton, in the open ocean, wheretheyappeartobebothabundantanddiverse.Asagroup,archaeansare,infact,astonishinglywelladaptedtolifeonEarth,nomattertheconditions.Most surprising is that this microbe, once considered rare and an isolated

phenomenon,isnowestimatedtooccupy20percentofthebiomassonEarth.In2012, scientists ledbyAndrewThurber atOregonStateUniversity announcedthat theyhadproved,forthefirst time, thatotheranimalscananddoconsumearchaeans,Thisimportantfindingmeansthatarchaeansarepartofthefoodwebintheocean.Alreadyknowntoconsumethegreenhouse-gasmethane,archaeansare eaten by worms living at deep-sea cold seeps in the North Pacific offnorthernCalifornia,inOregonandinCostaRica.Theseworms,fromthefamilyDorvilleidae, appear to use their teeth to scrape archaeans off rocks. WhenThurberandhiscolleaguestriedtotraceconsumptionofarchaeansthroughlipidtypes and other mechanisms, they found nothing, because the chemicals andproteins broke down inside the worms. The only way the scientists coulddocument eatingwasby tracing the isotopic biomarkers from themethane thearchaeansconsumed.It would be valuable enough if archaean research led to biotechnological

advances in medicine, renewable energy and environmental cleanup andprovided clues to the earlyhistoryofourwaterplanet.Yet archaeans are alsoprovingtohavearoleintheecosystemservicesofnitrogencyclingandasthemainmechanismforkeepingmarinemethaneoutof theatmosphere.Thedeepoceanhaslargeamountsofmethane,andarchaeansconsumeitbeforeitreachesthewatercolumn.Thisdoesmoretofightglobalwarmingthanall theFortune500companiescombined.The classification of archaeans is a new field. Analysis of the archaean

genome has focused on uncovering the genes that archaeans share with otherlife-forms and distinguishing the genes that are separate. Their evolutionaryhistoryisindependentofanyotheranimalsthathavebeenstudied.Sofar,thereare four named phyla, but there may be many more. Archaeans replicateasexually in a processknownasbinary fission.Scientists disagreeonwhetherdifferent archaeans should be considered separate species. From the point ofview of appearance and DNA findings, it would seem that there are separatespecies, but it remains unclear whether gene transfer is prohibited. Only asscientistscharacterizemanymorearchaeanswill theybeabletopiecetogetherthearchaeans’lifehistoryaswellastheirevolutionaryhistory.Itwilltaketime

beforescientistscanagreeonwhetherarchaeans,aswellasbacteriaandothermicrobes,deservespeciesstatus.Perhaps themostunexpectedoutcomeof thehydrothermal-ventwork is that

geologistswhosimplysetouttoinvestigateseafloorfissuresarenowinleaguewithmarinebiologistswhojustwantedtolearnaboutgiantclams,musselsandtubeworms and how they made a living so far away from sunlight. Thesescientistsarenow,inturn,workingwithmicrobiologistswhoneverdreamedofgoingtoseaorstudyinglifeontheoceanfloor.Invariouscountriesthroughoutthe world, “archaea centers” have become part of university biologydepartments,whereresearchersengageinculturingandcharacterizingarchaeansand their peculiar cellular molecular biology. As such partnerships conductresearch into the origin and evolution of these new life-forms, their work islaunchingdebatesaboutthepossibilityoflifedevelopingonotherplanets.Itisamazingtoconsiderthattheseorganismsformingthisnewlineageoflife,thesetinyseacreatures,werediscoveredinthecrevicesoftheEarth’smoltenmagmachamber,onemightsayattheveryGatesofHell.Todate,onlyafewtinypuzzlepiecesofthisnewarchaeanworldhavebeen

studied. Compared with the eukaryotes and bacteria, archaeans have a lot ofcatchinguptodo.Whatwedon’tknowgreatlyexceedsoursliverofknowledge.Whoknowswhatwildridethearchaeansmayyettakeuson?

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Thesebacteriahelptofuelanentireecosysteminthedeepsearemotefromthesun.Thebacteriafoundintubewormscombinewithoxygenfromtheseawaterandhydrogensulfidefromtheventfluids.Thebacteriathenoxidizethehydrogensulfidetoproduceenergy.

PARTFOUR

Previous page: A male killer whale (Orcinus orca), swims through the coldwatersoffKristiansundandNordmøre,Norway,returningeverywinterinsearchofherring.

I

CountingtheCitizensoftheSea

NALIFETIMEoflookingatthesea,Aristotle(384–322BC),theworld’sfirstmarinebiologist, identified some180marine species, anumber thatincludedcrustaceans,echinoderms,mollusksandfish.Andsothenaming

andcountingbegan.By1749,the42-year-oldpioneersystematistLinnaeus,whosebirthnamewas

CarlvonLinné,declaredtherewereabout2,000fishesandafewhundredothermarinespeciesdividedamongtheplants,worms,amphibiansandtetrapods.Asfounderofthebinomialsystemofnamingspecies,Linnaeushadbythengivennames tomostof them.Widelyknownand respected forhisSystemaNaturaeseries, he proudly declaredwhat he considered to be the absolutemeasure ofdiversity,consistingof“26,500speciesoflivingbeingsintheworld.”Linnaeus stopped counting far too soon, but he knew that identifying and

classifyingspecieswasthefirststep.Ifhumansareevertolearnmoreabouthowthesecreatureslive,whattheirhabitatneedsareandwhattheycontributetothelargestecosystemsintheworld,it’sessentialthatweknowwhotheyare.From 1872 to 1876, marine zoologist Sir Charles Wyville Thomson

commanded the British ship HMS Challenger on a mapping and collectingexpeditionthatlastedmorethanthreeyears.Theworldwidevoyageresultedinthe discovery of 4,717newmarine species,manyofwhich lived below1,800feet (550 m), a depth at which early-19th-century British naturalist EdwardForbes, who had focused only on European waters, contended no life couldexist.Thomson’svoyagewasa turningpoint.Until the late1800s,museum-based

scientists received specimens collected from afar and evaluated and catalogedthem.AftertheChallengerExpedition,scientistsbegangoingtoseatodotheirowncollecting,armedwithnewknowledgeaboutmarineanimals.Thenumberofnewspeciesdiscoveredandidentifiedexploded,andthesheerdiversityoftheworld’screaturesbegantorevealitself.

In1959,Anglo-AmericanzoologistG.EvelynHutchinson,consideredoneofthe fathers of modern ecology, puzzled over the underlying logic of speciesdiversity.“Whyaretheresomanykindsofanimals?”heasked.Theanswerlaypartly in the extraordinary diversity of habitats on Earth, which Hutchinsonconsideredmainly land-based.He estimated theremight be about onemillionspecies globally, of which 75 percent were insects. Even then, the “bestinformation”wasthatonlyatinyproportionofallspecieslivedintheocean,nomatterthatlifehadstartedintheseaandthatweliveonawaterplanet.

Formallydescribedin2013,thisdeep-seaseacucumber(Laetmogonebilletti)livesonthesteepslopesoftheMid-AtlanticRidge.Manyspeciesofthesedetritus-recycling“earthwormsofthedeep”areidentifiedbythenumberandshapeoftheirossicles—smallbonystructuressituatedwithinthedermalskin

layerthatappearaslightishdots.

ItisJanuaryinGerlacheStrait,intheAntarcticPeninsula.Alargekillerwhale(Orcinusorca)eyesabite-sizedWeddellseal.ThisAntarcticecotypeoforcas,knowntofeedonmarinemammals,createswavestowashsealsofftheicefloesandintothewater,wheretheycanbereadilysnatchedup.

Showingwhythisspecieswasoriginallycalledthe“whalekiller”(invertedlaterto“killerwhale”),anAntarcticorcaharassesamatureminkewhale,preventingitfromdivingtoescape.OneecotypeofAntarctickillerwhalefeedsmainlyonminkewhalesandtheoccasionalsouthernelephantseal.

Whether Hutchinson was aware of ichthyologist John E. “Jack” Randall isunclear.Inthe1950s,Randallstartedhislongcareerseekingoutandidentifyingmarinespecies,anundertakingthatcontinuestoday.Overmorethan60yearsofdedicatedoceanprospecting,Randallhasclockeduparecord680validmarinespecies—morethananyothertaxonomistinhistorysinceLinnaeus.Most of the big marine mammals were identified in Linnaeus’s time, with

certain clarifications and separations of species determined as whale researchintensifiedinthe20thcentury.Yetthenewspeciesbeingdiscoveredtodayarenot just fish and the odd invertebrate. Since 2002, three new beaked whalespecies in the Pacific and Indian oceans have been named based on newlydiscoveredorreclassifiedmaterials.TheforgottenDeraniyagala’sbeakedwhale(Mesoplodonhotaula)was resurrected as recently asFebruary2014, thanks toDNAsamplingoffleshandbonesrecoveredinthewesternPacific.Howcanwhalespecies remainundetectedandundiscovered in theocean in

viewoftheirsizeandneedtosurfacetobreathe?Mostofthe22beakedwhalespeciesdiscoveredtodatelivefarfromland,diveforanhourormoreatatimeand generally elude human attempts to find, much less identify, them. Mostbeakedwhale speciescannotbepositively identifiedat sea.A researchermustfind a male skull on a beach, because in beaked whales, only the male hasdiagnostic teeth thatcanbeused tomakeapositive identification,andinmostcases,thiscanonlybeachievedbycloseexamination.Beakedwhalescientists,suchasJamesMeadoftheSmithsonianInstitution,contendthattheremaywellbeafewmoreundiscoveredbeakedwhalespeciesoutthere.Whale,dolphinandporpoise (cetacean) taxonomist William Perrin, who has had a new beakedwhale species named after him, has estimated that one to fivemore cetaceanspeciesremaintobefound.Asdiscoveriescontinuetobreak,geneticworkonwhales,dolphinsandmany

otherfishandinvertebratespecieshasclarifiedsomeofthespeciesdesignationsmadebytraditionalzoologists—thosewhohavedefinedspeciesbasedmainlyonskulls,with particular reference to the teeth.The external body shape remainsimportant for identification as well, but genetics has the power to adjust andsometimesrewritepreviousfindings.Geneticworkmaysoonsplitseveralwell-knownwhaleanddolphinspecies,suchasthekillerwhale.ThereareNorthPacificfish-eating“resident”killerwhales,marine-mammal-

eating “transient” killer whales and the “offshore” shark-eating killer whales;there are three ecotypes of Antarctic killer whales living, respectively, onAntarctic toothfish, penguins and minke whales. There are potentially moreecotypes of orcas in other oceans.AlongwithAmerican researcherRobert L.Pitman,Netherlands-born illustratorUkoGorterhasproducedaposterwithno

fewer than 10 ecotypes or forms of orcas—five in the southern hemisphere,mainlyaroundtheAntarctic;andfiveinthenorthernhemisphere.Atleastsomeof these, andmaybemost of them,may turn out to be separate species. Eventhoughkillerwhalesfromdifferentecotypesmayliveinoverlappingareasandpassoneanotherintheseafromtimetotime,theydonotassociateorexchangesounds.Theyhavecompletelydistinctdialectsandseemtotreatoneanotherasseparatespecies.Thusbesidesgeneticevidenceanddifferentphysicalfeatures,thereisalsostrongculturalevidence—widelyvaryingeatinghabitsanddialects—fuelingtheargumentforsplittingthekillerwhalespecies.Awardinganimals“species status” provides the basis for recognizing their conservation needs.Evaluatingdifferencesinageofmaturity,numberofoffspring,growthrateandsizeofbreedingunitgivesconservationbiologiststhetoolstheyneedtoassessthevulnerabilityofaspecies.Inthelate1990s,JesseAusubelofTheRockefellerUniversityandtheAlfred

P. Sloan Foundation, inNewYorkCity, andmarine scientist FredGrassle ofRutgers,TheStateUniversityofNewJersey,metupforabeer.OneofthefirstquestionsAusubelaskedGrasslewashowmanyspecieshefiguredlivedinthesea.Grassleistheauthorofaslimchapteronoceandiversitythatappearedinavolumedetailingthethenup-to-dateUnitedNationsEnvironmentProgramme’sGlobalBiodiversityAssessment.Grasslerepliedthatnobodyknew,eventothenearestpowerof10,andthathewasembarrassedtoadmittherewasnolistofwhatcouldbefoundintheseathatcouldbeusedevenasavalidstartingpointforcounting.Grassle’s revelation toAusubel led to the ideaofaproject thatwouldcount

“allthefishesinthesea.”Itsoonexpandedtoanambitiousundertakingtocounteverythinginthesea!Whatcouldbesimplerorstrongerintermsofengagingthepublic,thefundingbodiesandthesupportinginstitutionsthantheideaoftryingto findand identifyall theocean’sanimals?As thesharedpassionaround thisideabegantopickupmomentum,theAlfredP.SloanFoundationofferedabigmoneycommitmentof$75million(U.S.)tofundwhatwouldbecomea10-yearproject (2000–2010).Universitiesandoceanographic institutionspledged shipsandshiptime.ItbecameknownastheCensusofMarineLife,andthegoalwasto evaluate and assemble everything that was known about the diversity,distributionandabundanceoflifeintheocean.Atworkshopsandmeetings,asscientists and policy-makers from many countries began planning a globalproject, it became clear that it was going to have to be a multidisciplinary,multinational,multimillion-dollar,multiple-year effort.After 60 someyears ofNASA’s funding the American space program and sprawling governmentdefensebudgetsfor“appliedscience,”itwasabouttimethatBigSciencepaidat

leastatokenvisittothedeepocean.Itwouldbecomemorethantoken.Thefinalpricetagwouldbe$650million(U.S.).

♦

InNovember2011,thisunidentifieddeep-seaseaurchinwasfoundonacoralseamountintheIndianOcean.Itusessuckersonitsfeettograbfood,thenscrapesawaypieceswithitsteethandtucksthemintoitsmouth,locatedontheundersideofitsbody.Manyoftheseseafloor“porcupines”arearmedwithpoisonousspines.

poisonousspines.

T

TheCensusofMarineLife

HEYEAR2000markedthebeginningofadecadeofdiscovery.Intheclosingyearsofthe20thcentury,expeditionstothedeep-seaventsintheRoseGarden,ontheGalápagosRift,aswellasClamAcres,Hole-

to-Hell,SnakePit,LuckyStrike,BrokenSpurand theMothraVentField,hadbegun toopenupanewworldwithnewanimalsandecosystems.Since2000,however,researchershavediscoveredmorenewventsintheSouthPacificandasfarnorthastheArctic,wherenoventswereknownbefore.Researchershaveloggedevenhottervents,atupto765degreesF(407°C),andeverdeepervents,downtothreemiles(5km)belowthesurface.Andtheyhaveuncoveredmanynewspecieslivingineachventfield.Deep-sea hydrothermal-vent explorations represented only a part of the

CensusofMarineLifework. Inall, some2,700scientistsand their supportingteamsfrom80countriesworkedon17projectareasorganized into threemaincategories:OceansPast(whathaslivedintheocean),OceansPresent(whatdoesliveintheocean)andOceansFuture(whatwillliveintheocean).Canadian marine ecologist Paul Snelgrove, who had been Fred Grassle’s

doctoralstudentandwhoseworkinitiallyfocusedonsedimentaryecosystemsonthe sea bottom, reported on the Census work in his bookDiscoveries of theCensusofMarineLife:MakingOceanLifeCount(CambridgeUniversityPress,2010).Snelgrove isnowaprofessor atMemorialUniversityofNewfoundlandand is the director of the Canadian Healthy Oceans Network. As he becamemoreandmoreinvolvedintheCensusofMarineLife,Snelgrovemovedupanddown the water column, branching into other ocean ecosystems and projectareas.According to Snelgrove, Oceans Past attempted to get a baseline for

measuringlossofdiversityandotherecosystemchangesintheocean.Themostobviousof thesewas thesevere reduction incommercial fishstocks.This losscouldbedemonstratedbythesubstantialdeclineinmaximumfishsizesdecade

bydecadeandbysucheventsastheextinctionofthegreatcodfishingindustryontheGrandBanksofNewfoundlandby1992.Most projects, however, fell under the category of Oceans Present, with

further subdivisions into geographic realms, global distributions and animalmovements.Researchersspentsometimeinthewell-studiedareasaroundNorthAmerica and the eastern tropical Pacific. They spent a lot of time on thecontinentalshelvesoftheArcticandAntarctic.While42percentoftheocean’scontinental shelves are in polar waters, these regions are comparatively lessstudied thanare temperate and tropical shelves.The researchers lookedon themap for areasnotwell represented indatabanks, inanattempt tomoveawayfromcoastal,surfaceandshallowwatersandintotheunknownoff-the-shelfandoffshorefarreachesanddepthsoftheocean.Theyknewthattheoceanwasanimpossiblybigplaceandthattheycouldnothopetograspthefullextentofthediversityofitsinhabitants,yettheywantedtocoverasmuchoceanaspossible.Onehigh-profileproject, theTaggingofPacificPredators (TOPP), followed

sharks, tuna, turtles, seabirds, marine mammals and other apex predators todiscoverwheretheytravelandhowtheyusetheocean.Thiskindofresearchcanfacilitate the identification of the critical habitat and migratory corridors ofanimalpopulations.LedbyStanfordUniversityprofessorandmarinebiologistBarbaraA.Block,TOPP researchers tracked sooty shearwaters as theymovedfromthefarsouthernwatersoffNewZealandtotheBeringSeaintheArctic,asif in pursuit of an endless summer. They trailedwhite sharks fromCaliforniainto thedeepPacific,halfway toHawaii.The sharksconvergedat amidoceanspotdubbedtheWhiteSharkCafébeforereturningtocoastalCaliforniatocatchmarinemammalsintheeasy-to-accesscoastalsealandsealioncolonies.TOPPfollowed leatherbackand loggerhead turtles thatbreedandhatchoff Indonesiaand elsewhere in thewesternPacific, then navigate thePacific as juveniles tofeedonabundantjellyfishofftheCaliforniacoast.TOPP foundclustersofhot spots in theCaliforniaCurrent,where abundant

nutrientupwellingsfuellargezooplankton,fishandsquidpopulations.Becausethehotspotscreatenumerousniches,theanimalsdonotneedtosimultaneouslycompete for the same food. The species either have different diets from oneanotherorhuntatdifferenttimes,seasonsordepths.Block and her colleagues suspected that the observed patterns of predator

distributionwereindicativeoftrade-offsbetweenthewatertemperaturesthatthepredators or their prey preferred, as well as access to areas of higherproductivity.TOPP’soverallfinding,asSnelgroveputit,wasthat“speciesoncethoughtto

wander indiscriminately have well-defined kitchens, bedrooms, hallways and

nurseries.”These“livingspaces”seemtobefairlyfixed.Thekitchensarealsoconsistently found in the same areas. Still, the study did find that with somespecies,oceanchanges,suchasadelayinseasonalupwellings,caninfluencethelocationofthekitchenandeventhemealoptions.OfftheCaliforniacoast,Californiasealionsnormallystayclosetohomeon

coastalrocks,takingexcursionsthatarenomorethandaytrips.Yetwhentheirusual home-based food supplies of squid and anchovies are scarce, they areprepared to travel up to 300miles (480 km) offshore and switch their diet tosardinesandrockfish.Thussealionsmayhavesomebuilt-inflexibilityintheirfeedinghabits thatwill give theman advantage if climate change affects theirfoodsupplies.Butifoceanchangesforcesealionsandotherspeciestotraveltounpredictable locations, it maymake lifemore complicated for designers andmanagersofmarineprotectedareas(MPAs),whowillhave toexpandexistingMPAsorcreateflexibleMPAnetworks.

Resemblingadelicatepinkflower,thisjellyfishlikesiphonophore(Athorybiarosacea)isonlyaninchwide(2.5cm).Itisacarnivorouscolonialanimalthatcatchesitspreywithstingingcells.ItwasfoundnearthesurfaceoftheSargasso

Seain2006byscubadiversonaCensusofMarineZooplanktoncruise,partoftheCensusofMarineLife.

Fiveofthe12CensusprojectsintheOceansPresentgroupfocusedonthedeepsea:abyssalplains,hydrothermalventsandcoldseeps,midoceanridges,continentalmarginsandseamounts.TheseprojectswerealmostguaranteedtouncovermanynewspeciesandtoresultinpotentialScienceandNaturecovers.Atminimum,theywouldproducegreatmaterialsforbloggers.Themandate ofOceans Futurewas tomonitor and use the vast amount of

information being obtained by Oceans Past and Oceans Present. In the late1980s,HarvardprofessorEdwardO.Wilsondreamedofadaywhentherewouldbe “an electronic page for each species of organism on Earth, availableeverywhere by single access on command.” The Internetwas young then andaccesstoitlimited.ThespeciespagesoftheEncyclopediaofLife(www.eol.org)fulfill Wilson’s dream, providing links to published and gray literature(information that lies outside the realm of published books and journals) andtherebyreducingtheneedfortime-consumingliteraturesurveysandrequeststofar-flunglibrariesbeforeresearchcanbeundertaken.Along with the Encyclopedia of Life, additional Census partner projects

included the World Register of Marine Species (WoRMS), a database oftaxonomic information on marine species (www.marinespecies.org), and theOceanBiogeographicInformationSystem(OBIS),adatabaseopentothepublictoaggregateandmakeavailabletheworld’sknowledgeaboutmarinespeciesonmapsforconservationandplanningofprotectedareas(www.iobis.org).Even with these tools, however, the biggest bottleneck in all biodiversity

researchand the limiting factor in theCensuswork, asSnelgroveexplains, is,wasandwillremaintaxonomy.“Thenumberofparataxonomists—thosewithsomewhatlimitedknowledgeof

taxonomy—has grown,” says Snelgrove, “but the number of really skilledprimarytaxonomistshasremainedflatandisdecliningasexpertsretire.Soeventhoughthenumberofauthorsoftaxonomicpapershasincreased,mostofthoseauthors are those who helped collect the material and have little capacity todescribenewspecies.”The reality is thatweneedmanymore taxonomists foreverybranchoflife.For some years after Linnaeus’s time, describing a specieswas amatter of

turning up something never before seen and then awarding a name to thatfinding. The name typically reflected the place or situation in which thediscoverywasmade,honoredadepartedcolleagueoranoldloveinterestorwasawhimsicalchoicerelatedtoapersonalimpressionofthespecies.Thesedays,thefindingandnamingareoftenonlythewell-separatedstartand

endoftheprocess.Themoresignificantandtime-consumingworkisevaluatingthe external and internal hard and soft anatomy of the potential new species.

Traditionally, thiswas based on an evaluation of the body shape and skeletonand focused on the skull parts, with strong emphasis on the teeth. Today, itincludes DNA analysis and a careful comparison to the genetic profiles ofrelated species, including those which are alive today and those which havebecomeextinct.Inthisway,thetaxonomistbeginstouncovertheevolutionaryhistory,thephylogeny,ofthespecies.Onlywhenthetaxonomistcanshoehornaspeciesintoitsplaceintheuniverseofspeciesthatliveorhaveeverlivedonourplanetcanwesayaspeciesistrulyidentified.Although complete information is never available, taxonomists work with

whattheyhave,uncoveringdisjunctpiecesofknownspeciesandtryingtofitthemissing species into a plausible place. They startwith class and phylum—theeasy stuff—thenmove on to order, suborder and genus. It can take dedicatedbiologists10yearsormoretodothenecessaryhistoricaldetectivework,whichincludescorrespondingwithmuseumsaroundtheworldandattendingmeetingsorworkshopswithotherspecialistsbeforetheycanputanametoanewspeciesorsplitanexistingspeciesandelicitthenecessarysupportfromcolleagues.Toshortcut the identificationprocess, theCensusofMarineLife recognized

that itwould requirenewgenomics technologies to identifyspecies,especiallydown to the microbe level. Early on, the Census encountered the work ofevolutionarybiologistPaulHebertoftheUniversityofGuelph,inCanada,whowaspioneeringamethodfor identifyingspeciesbasedona tinyDNAsnippet.Heberthypothesized that the first648unitsofacertaingenecouldbeused toidentify every species. Soon dubbed “DNA barcoding,” the technique wasnamedafter theuniversalproductcodethatdistinguishescommercialproducts,from books and batteries to cereal, at the checkout counter. DNA barcodingenables rapid identificationof a species thatmight differ frommale to femalebut has the sameDNA barcode, for example, ormight superficially resembleanotherspeciesbutpossessabarcodethatwouldindicatetwodifferentspecies.ButmanytaxonomistswereunhappywithHebert’sshortcut,sayingthat this

wasnotproper taxonomy.Darwinhadsaid thataspecieswaswhatagroupofexpertsdeterminedandagreedwasaspecies.Thegroupofexpertsthatincludedthe taxonomists for the various groups of ocean species was not at all inagreement.Still,DNAbarcodingwasadoptedforuseaspartoftheCensus,anditproved

tohavesubstantialvalue,evenifnew-speciesstatuscouldnotbeawardedbasedonbarcode identityalone.Recognizinganewspeciesmust stillbearguedandagreeduponby theexpert taxonomists forparticulargroupsoforganisms.Butwithsome90,000marinespecies logged intocomputers, thisprocesshasspedupidentificationsofspecieswhiletheyarebeingcollectedatsea.

Through the Census of Marine Life decade of discovery, some 540 oceanexpeditionswerelaunchedtoexplorethedistribution,abundanceanddiversity,orrichness,ofspeciesintheocean,andtheresults,althoughslowatfirst,begantoaccrue.Inall,theseexpeditionsandtheworkthatleduptoandfollowedfromthemcost$650million(U.S.)andresultedin30millioncollectedsamples.Thatworksouttoalittlemorethan$20persample.With somuchwork sprawlingover theknownandunknownocean,Census

scientists realized thatgettinganoverviewof thehugescopeandextentof thework,muchlesscommunicatingittothepublic,wouldbeachallenge.That was where Paul Snelgrove came in. Toward the end of the Census,

Snelgrovewas given the task of pulling together all the diverse and extensiveresults.Themore than2,600scientificpapers thathadcomeoutof theCensusby then were one thing, but these would be read only by specialists in eachdiscipline. The project needed to report on the work in an accessible,interdisciplinaryway to all participating scientists and funders, as well as thegeneralpublic.Snelgroveretiredtohisofficetoreadthepapers,sendfollow-upe-mails and talkwith colleagues topreparehis synthesis.Thiswork led tohisbookDiscoveriesoftheCensusofMarineLife:MakingOceanLifeCount.AspartofaTEDtalkinEdinburgh,Scotland,inJuly2011,Snelgroveshared

theoverviewoftheCensusparticipants,whohadbeendeeplydismayedbythestate of commercial fish populations and the degradation of nearshoreecosystems.Yetatthesametime,hesaid,theCensushadrevealedextraordinarydiversity,withmanynewandsurprisingspecies,andhadshown“howtenaciouslifeisintheoceans.”That tenacity includes the diversity of animals at the hydrothermal vents,

whichflourishinconditionsmostofuswouldconsidersimilartolivingonthesunnysideofMercury.Buttheseanimalslivelargelyindependentlyofthesunandphotosynthesis.TheCensusturnedupaspeciesthoughttohavegoneextinct50millionyearsago—theJurassicshrimp.ItwasdiscoveredaliveandwelloffthecoastofAustralia.TheCensus also discovered a newbigfin squid, sometimes called the long-

armsquid,inthedeepwatersabovetheMid-AtlanticRidge.PlacedinthegenusMagnapinna, the bigfin squid is one of the ocean’s strangest and least-knownsquid. At 22 feet (7m) long, it is one of the larger new species encounteredduringtheCensus.Itsarmsandtentaclesareallthesamelength,whichisuniqueforsquid;theygrowupto20timesthelengthofthemantle.Theappendagesarepoised perpendicular to the squid’s body, giving the impression of “elbows.”Finally, it has huge fins that represent about 90 percent of the length of itsmantle. Still to be named, the squid is considered a fifth species in the genus

Magnapinna. Researchers speculate that it may hunt by dragging itsextraordinarilylongarmsandtentaclesacrosstheoceanfloor,snatchingitspreyfromtheseafloor.Noadultbigfinsquidhaseverbeen recovered,although theAlvin submarine is thought to have photographed one in October 2000 in thenorthernGulfofMexico.

FoundintheSargassoSeabyWoodsHoleOceanographicInstitutionresearchersduringtheCensusofMarineZooplankton,theseloops,chainsandspheresarecommonplanktonicanimalscalledcolonialradiolarians.Atabouthalfaninch(1cm)inlength,eachshaperepresentshundredsofsingle-cellanimalsembeddedinajellylikesubstance.Theydriftwiththesurfacecurrentsandcanphotosynthesize.Notably,theyarepredatorsofothersmallplankton.

This deep-sea soft coral (Anthomastus sp.),whichmay be a new species,wasfoundinDecember2011onacoralseamountintheIndianOcean.Itliveswithasymbiotic (commensal) bristleworm,orpolychaete, oneof themarine annelidworms.

Newtoscience,thescaly-footgastropod,orseasnail,livesonthehydrothermal-ventchimneysoftheDragonVentField.ItwastentativelyidentifiedaChrysomallonsquamiferumandistheonlyknownanimaltouseironasadefense.Ironsulfidearmorstheshellandthescalesonthefoot,servingtoprotecttheseasnailfrompredatorsandfromthehightemperaturesofthehotwater.Notethatapolychaetewormislivingonthegastropod’sfootinasymbioticrelationshipknownascommensalism,believedtobenefitthewormwithoutharmingthesnail.

Thisviewoftheopenshellofadeep-seamussel(Bathymodiolusindica)revealsanewspeciesofcommensalpolychaetescalewormlivingwithin.ThesemollusksformpartofthecommunitythatlivesaroundchimneysandblacksmokersattheDragonVentFieldintheSouthwestIndianOcean,whichwasexploredinNovember2011.

How could such creatures have beenmissed before? The answer is simple.Researchers had not spent enough time in the deep waters where this animallives.Evenifabigfinsquidhadbeenfoundstrandedonabeachorpulledupbyafisherman,theeventwouldgounrecordedwithoutasquidspecialistonhandtomakeanidentification.In 2010, toward the end of the Census decade, Snelgrove announced that

researchershadsofarfoundsome6,000newspecies in theoceanandthat thecurrentestimatesofdiversitywereapproximately226,000species.Thatdidnotinclude bacteria, archaeans and other mostly single-cell microbes. SnelgrovereportedinhisTEDtalkthatscientistsbelievetheyknowroughly9percentofthe species in the ocean. “Thatmeans 91 percent, even after the Census, stillremaintobediscovered.Andthatturnsouttobeabouttwomillionspeciesonceall is said and done. So we still have quite a lot of work to do in terms ofunknowns.”In an attempt to further refine the estimates of the total number of ocean

species known and yet to be known, environmental biologistWardAppeltansand117colleaguescompiledadetailedpaperinDecember2012inwhicheachauthorreportedonthecurrentstatusofdifferentspeciesgroups.Appeltansandhiscolleaguesreviewedallpreviouspredictionsofthediversity

ofoceanspecies,which ranged from300,000 tomore than10millionspecies.They considered the huge problem of synonyms—species burdened with avariety of scientific names that, in fact, all describe the same species. TheAppeltansetal.paperreportedabout170,000knownsynonyms.The giant squid, for example, had been assigned up to 21 species names

because so many researchers had been in such a rush to have their namesattachedtopapersthatdescribedthisultimatecreatureofthedeep.Inthe1980s,giant squid researchers reduced that number to nomore than three species. In2013,geneticresearchrevealedthatthereisonlyonespecies,Architeuthisdux,theoriginalgiantsquid,whichnowreignssupreme—andalone.Mostexcitingofall,Appeltansandhiscolleaguesconcludedthatasmanyas

20,000specieshadbeendescribedinthe10yearsoftheCensus—2,000ayear,or5½aday—morethanthreetimesthenumberSnelgrovehadconcludedwhenhehadsynthesizedthework2½yearsearlier.Theexpertsdeterminedthatthereweresome58,000to72,000speciesstillawaitingformalstudyanddescription.Manyofthesewouldlikelybenewspeciestoo.“Morespeciesthaneverbeforearebeingdescribedannuallybyanincreasing

numberofauthors,”wroteAppeltansetal.Examiningthevariousestimatesandtakingpredictionsfromeachofthespeciesexperts,Appeltans’groupestimatedthat thereare482,000 to741,000speciesyet tobediscovered.Thismakes the

absolute diversity of the ocean somewhere between roughly 700,000 and onemillion species.While this estimate is far lower than Snelgrove’s twomillionandFredGrassle’soriginal10million,futuremarinebiologistsandtaxonomistsneverthelessfaceamajorundertaking.Atthecurrentrateofnewdiscoveryandtaxonomicassignmentof2,000per

year,thetaskofcatalogingalltheocean’sbiologicaldiversitycantheoreticallybeexpectedtolastafurther240to370years.Withthelowerdiversityestimate,thiswouldtakeusmidwaythroughthe23rdcentury;withthehigherestimate,itwouldbeclosetotheendofthe24thcentury.ButAppeltansandhiscolleaguesaremoreoptimistic,hintingintheirpaperthatcurrentidentificationmethodscanaccelerate,inwhichcase“mostspecieswillbediscoveredthiscentury.”The truth is, no one knows the true extent ofmarine diversity—researchers

havebeenfaroffinthepast.Andthereareevenbiggergapsamongthemicrobesthat Appeltans’ group did not consider. While bacteria, archaeans and othermostly single-cell organisms may not be considered species as such, theirdiversity is yet to be grasped. InSnelgrove’sTED talk, he hinted at the greatunknownsrelatedtomicroberesearch.HeshowedabacteriumthatwaspartofmatsfoundoffthecoastofChile.“ThesematscoveranareathesizeofGreece,”said Snelgrove. “And this particular bacterium is actually visible to the nakedeye.But you can imagine the biomass that it represents. The really intriguingthingaboutthemicrobesisjusthowdiversetheyare.Asingledropofseawatercould contain 160 different types ofmicrobes.And the oceans themselves arethought potentially to contain as many as a billion different types. So that’sreallyexciting.Whataretheyalldoingoutthere?Wedon’tknow.”Microbeshavebeencalculatedtomakeup90percentofthetotalbiomassin

the sea. Microbes extend even into the seafloor, with some found livinghundreds of yards below the bottom. This means that taken together, all thewhales,sharks, tunaandotherfishandthemanylargeandsmall invertebrates,includingallthesquidandtheextraordinarilynumerousjellyfish,representonly10 percent of the ocean’s biomass. Themost common form of life on PlanetEarthisnotHomosapiensorthecommonhouseflyoroneoftheantspeciesthathave colonies in the millions. Nor is it the ubiquitous copepod. The mostcommonlife-formisamicrobecalledalphaproteobacteria.The next few generations of marine biologists and conservationists have

before them what may be the last great exciting era in the discovery of ourplanet’slife.Let’shopesomeofthemcantellstoriesascompellingasthosetoldbyEdwardO.Wilson,EdieWidder,SylviaEarle, JamesCameron,CindyLeeVan Dover, Paul Snelgrove and Richard Ellis, all of whom have brought tovibrant life the current deep-sea underwater rogue’s gallery of big and small

creaturesofthedeep.TheCensusofMarineLifehasbeenagoodbeginning.Keentokeepupthe

momentum,Snelgroveandhiscolleagueshaveputtogetherafollow-upprojectcalledLifeinaChangingOcean.Whiletheirinitiativehasyettocommandthelevelofparticipation,interestandfundingthatthe10-yearCensusenjoyed,itisastartinbuildingonthesuccessesofitsprecursor’slegacy.Meanwhile,oceanresearchingeneralanddeep-seainvestigationsinparticular

are accelerating, with new collaborations between scientists and institutions,some of which have grown out of the Census work and some of which areindependent. Deep-sea photographer David Shale, veteran of the BBC BluePlanet series, joined the November 2011 expedition to the Southwest IndianRidge(SWIR)withdeep-seabiologistsJonCopleyandAlexRogersaboardtheRRSJamesCook.AmonganumberofnewspeciestheyturnedupintheDragonVentFieldin

the Southwest Indian Ocean was a sea snail, referred to affectionately as thescaly-foot snail. Living on the hydrothermal-vent chimneys, the snail is oftenfoundinthecompanyofpolychaeteworms,whicharesometimesattachedtoit.Ithasaspecial footcovered inarmorlikescales,perhaps toprotect it fromtheextremelyhotwaterandhydrogensulfidesteamingoutofthevolcanicseafloor.Itswork-boot-likeprotectionmayalsomakethesnailunappetizingtopredators.Asithappens,thescaly-footsnailhadbeenfound10yearsearlierontheCentralIndianRidgebutnotdescribed scientifically.The sea snailhasbeengiven thenameChrysomallonsquamiferum,andthetypespecimenwillbeassignedtotheSouthwestIndianRidge.Shalephotographedanothernewspecies livingbeside thescaly-footsnailat

theDragonVentField:theYeticrab(Kiwasp.SWIR),namedforitspatchesofsetae, or bristles, used to collect chemosynthetic bacteria that it is thought toingestasahandyfoodsource.(Yeticrabsofvariousspecieshavebeenturningup at other vents too, but this one has yet to receive its full scientific name.)Therewas also a smooth snail, or gastropod, from an entirely new genus andspecies (Gigantopelta aegis). Aswell, a new red scalewormwas found livingcommensallywithinthemusselBathymodiolusindica.Althoughithasnotbeenformally described yet, this scaleworm is being called Branchipolynoedracovermis. At the same site, a new species of white free-living scaleworm(Branchinotogluma lancellotti) was discovered. The scientists continue to sortoutothersuspectednewspecies,suchasstalkedbarnaclesandseacucumbersoftheChiridotagenus.Wholehostsofstrangenewhydrothermal-ventspecieshavebeenfoundatthis

ridge and others. None of these creatures has employed bioluminescence, as

havethemesopelagicanddeep-seafish,oracoustics,likethewhales,toengagetheirworld.Theventspecieslivebytherulesofanotherworld.The 2011 Southwest Indian Ridge expedition also investigated the nearby

seamountsCoral,MelvilleBank,MiddleofWhat,SapmerandAtlantis.There,manynever-before-photographedspecieswerediscovered,someofthemnewtoscience, such as a species of Acanthogorgiidae coral from a family of coralknowninEuropeanwaters.The2011SouthwestIndianRidgeexpeditionwasoneofaseriesofSouthern

Ocean expeditions from 2009–2011 led by Alex Rogers, a professor ofconservationbiologyattheUniversityofOxford,joinedvariouslybyateamofresearchers from theBritishAntarcticSurvey, theWoodsHoleOceanographicInstitutionand theU.K.universitiesofSouthampton,BristolandNewcastle.Akey area of exploration was the East Scotia Ridge, near Antarctica. Censusscientists had already shown that deep-sea octopods were using the SouthernOceanasagateway to theAtlantic,Pacificand Indianoceans.Rogersandhiscolleagueswanted to test the theory thatcrabs,clams,shrimp,snailsandotherspecies in the hydrothermal-vent communities might likewisemove from oneventtoanother,acrossandbetweenoceanbasins,viatheSouthernOcean.Forseveralweeks,Rogers’teamemployedavarietyofmethodstoexplorethe

region and was surprised to find a community of unique species—apparentlyendemic to the site. As the team reported: “These included huge densities ofanother newYeti crabwhich has been namedKiwa tyleri, peltospiroid snails,limpets, stalked barnacles, anemones, sea spiders and octopus. The findingsindicatedthattheAntarcticrepresentedadistincttypeofventcommunityfromelsewhereandthattheexpectedlinkagestootherventsystemswerenotpresent,possiblybecauseoftheextremelowtemperaturesofthewaterssurroundingthevents.”Sometimes,disprovingahypothesiscanbeevenmoreexciting thanproving

it.

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Amotherandcalfhumpbackwhale(Megapteranovaeangliae)stayclosetogetheronthebreedinggroundsoffTonga,intheSouthPacific.

F

FindingaPlaceforOceanCitizenstoLive

ORNEARLY 20 years, most of myworking hours have been spenttrying to identify and protect habitats in the sea forwhales, dolphinsand other marine life. For me, this work started even earlier, with

effortsinthe1980stoprotecttherestingareasandrubbingbeachesoforcas,orkiller whales, off northern Vancouver Island, in the North Pacific. In thecompany of fellow researchers and conservationists, I spent 10 summerswithseveral pods, or family groups, of killer whales, and we came to know theirhabits and favorite habitats. When MacMillan Bloedel Ltd., then Canada’slargest logging company, announced that it was going to boom logs in thepreciselocationwheremostoftheorcasgathered,weputasideourday-to-daywork to let the world know what was about to happen. We succeeded inprotectingapieceoforcahabitatatRobsonBight.Later,itbecameclearthatweshould have demanded a much larger area, with stronger managementprovisions.Backthen,weweren’tthinkingbigenough.Oureffortstoprotectwhaleanddolphinhabitathavesinceexpandedtoevery

sea, fromtheMediterranean to thegreatRossSea inAntarctica. Inaddition toconservation campaigns, I have commissioned and participated in researchprojects and expeditions, helped produce documentary films, engaged ininterviewswith video and print journalists and linked upwith two round-the-worldsailingracestobringattentiontotheneedformarinehabitatprotection.Ihave delivered two editions ofMarine Protected Areas forWhales, DolphinsandPorpoises(2005and2011),alongwithnumerouslectures,blogs,tweetsandarticlestoadvancetheworkofcreatingandimplementingeffective“homesforwhalesanddolphins.”Thisworkisstillinitsinfancy.

Aristotleobservedandwroteaboutdolphins,probablyinreferencetotheshort-beakedcommondolphin(Delphinusdelphis),whichwasoncefoundinlargenumbersinthewatersoffGreece.Today,thisspeciesiscriticallyendangeredthroughouttheMediterraneanSea.OnestrongholdistheAlboranSea,inthewesternMediterranean,whichhasbeenproposedasaprotectedareaforD.delphisandsevenotherwhaleanddolphinspecies.

Ihavefocusedonhabitatconservationforwhalesanddolphinsbecausetheyare charismatic sentinel species that inspire popular public campaigns on theirbehalf,thusbringingprotectiontoawiderangeofspeciesthatsharetheirlargehabitats.Tethered to thesurfaceby theirneedtobreatheandvisiblypresentatthetopofthefoodchain,whalesanddolphinsofferuscluesaboutthehealthofoceanecosystems.Inasense,theyrepresentthemanydifferentspecies,knownand unknown, that together play a role in creating the natural functions andservicesuponwhichtheoceansandourplanetdepend.My concerns, and those of my colleagues, embrace the big picture that

includesthelittlestuff;thatis,allthecomplexlyinteractingpiecesthatmakeupanecosystem.Asweare learning, thegreaterour ignoranceaboutaspecies,ahabitatoranecosystem—andhowtheyall fit together—thebiggerwehave tothinkandthelargertheareaweneedtosetaside,ifonlyasahedgeagainstthatignorance.Unfortunately,manypolicy-makersandpoliticiansdonotrecognizeeither the value or the limitations of scientific research, much less their ownignoranceaboutit.With its immensevolume, theocean representsmore than99percentof the

living space on Earth. The deep-sea and pelagic, or open ocean, ecosystems,suchasthosethatsupportwhalesanddolphins,extendforgreatdistancesacrossthe surface of the sea aswell as into its depths.An extraordinary diversity ofanimalsandecosystemsisyet tobediscoveredandunderstood.Thoseprofiledinthisbookarejustthebeginning.Asextensiveas theocean is, it isa fluidworld,ever inmotion.Weneed to

appreciate this tograsp thenatureofoceanecosystemsand tounderstandhowanimals exploit them.Manymarinemammals, fish and seabirds, for instance,feed in areas where nutrient-rich water upwells to the surface, fueling theexplosionsofphytoplanktononwhichzooplanktonandfishdepend.Theseareasoffoodabundancechangefromyeartoyearandevenwithinaseason,asoceancurrents,temperaturesandsalinitiesvary.Theecosystemsthatsupportwhalesanddolphinsextendfarinland.Notonly

do somedolphins live in estuaries, freshwater lakes and rivers, but their prey,suchassalmon,migratesupriversanddeepintoforests.Duringmyyearswithfish-eatingresidentorcasalongtheBritishColumbiacoast,Istoodinthemiddleof salmon-rich estuaries towatch these fish spawn andwonderedwhether theloggingupstreamwouldaffecttheirhealthandleadtotheirdecline.Today,BritishColumbia’s coastal salmon runs are approximately halfwhat

theywereattheirpeak,beforeintenselogging,dammingandfishingtooktheirheavytoll.Hasthereducedfoodavailabilityaffectedkillerwhales,alteredtheirtravelpatterns,forcedthemtoexpandtheirrangeandlimitedtheirreproductive

success?Towhat extent are salmon farms and the increasing noise from shiptrafficandhydrocarbonexplorationcontributingtoecosystemdecline?Multiplefactorsareresponsibleforthesouthernkillerwhalecommunity’sbeingdeclared“endangered,”butfoodsupplyandthechallengesoffindingandcatchingpreyinalessthanhealthyenvironmentappeartobepartofthestory.In 1999, with Russian marine mammal biologist Alexander Burdin, I

cofoundedtheFarEastRussiaOrcaProject,anongoingRussianresearchprojectthatstudiesorcasandothermarinemammalsfromtheKamchatkaPeninsulaandtheKomandorski(Commander)Islands,intheRussianFarEast.Eachdayinthefield,weencounterseaotters,harborseals,northernfurseals,Stellersea lionsandup tosixspeciesofsalmon.Allare foodformammal-eating transientandfish-eating resident killer whales. And all these species live together ininterdependentrelationshipsthatextendalongthebeachesandrockyshorelinesand into estuaries and up rivers. If the river basins become polluted, theshorelinedevelopedandtheriversdammedforhydroelectricpower,thesalmoncannotspawn. If thewaterqualitydeclines, the impactseventuallyshowup intheopensea,andthewholeecosystemstartstodegrade.By 2007,we had already begun to notice intense localized fishing in some

areas aroundKamchatka that appeared to have altered orca travel patterns. In2008,ourRussian team took its long-term research from theopenunprotectedwatersalongthecoastofKamchatkatothelargestmarineprotectedarea(MPA)inRussianwaters,theCommanderIslandsStateBiosphereReserve,justbeyondthefarwesternendoftheAleutianIslandschaininAlaska.Atthesametime,weexpandedourworktoincludeotherspeciesofwhalesandthelargerecosystem.Our goal is to gather detailed data on this ecosystem in its relatively pristineconditionthatcanserveasabaselineagainstwhichwecanmeasurethedeclinewemayseehereandinotherareasoftheArcticwatersinthefuture.Forthemostpart,thekillerwhales,humpbackwhales,Baird’sbeakedwhales,

Dall’s and harbor porpoises, fur seals, sea otters and other species in theKomandorski Islands have healthy-sized populations and remain relativelyundisturbed.Ourtaskistotrytoquantifyhowalltheseanimalsusetheirhabitat.Whichhabitatsare important for feeding,breeding,nursing, raisingyoungandothersocialpursuits?Ifwecangainsomepredictiveabilityfortheseandothermarinemammal populations in theNorthPacific, perhapswe can define theirimportant habitats and determine the level and extent of protection needed topreservetheirecosystems.At theWorldParksCongress inVenezuela in1992, I submitted apaperon

MPAs for whales, dolphins and porpoises to assess the status of and try toimagine the long road ahead forwhale habitat conservation. I presented three

casestudies:Scammon’sLagoonforgraywhalesinMexico;RobsonBightforkillerwhalesonVancouverIsland;andtheIndianOceanWhaleSanctuary,ano-hunting zone for all whales established by the International WhalingCommission.At that time, therewere only a few dozen areasworldwide thataimedtoprotectwhalehabitat.Whilehundredsofpapersonmarinethemeswerepresented at the conference, only one other paper mentioned whales anddolphins.Not even one paper raised the need for largeMPAs.Back then, theonlyMPAofanysizewasAustralia’sGreatBarrierReefMarinePark.Jumpingto thepresent,wefindsome570existingMPAsthatprotectwhale

anddolphinhabitatsinthewatersofmorethan100countries.Anadditional138areas have been proposed.Even so, these areas identify only a fraction of thewhale habitats in the sea. It’s a start, butwe still can’t be certain thatwe areprotectingthemostimportanthabitats.ThestoryforallMPAsintheoceanissimilar.Asof2014,therearemorethan

7,000MPAsforawiderangeofspeciesandecosystems.Thatmaysoundlikeanencouragingnumber,butintermsofthesurfaceareaprotected,itislessthan3percent of the ocean. It’s a longway from the 12 percent that is protected onlandandthe“10percentby2020”minimumtargetforMPAsthatwasagreedtoby more than 100 countries at the Convention on Biological Diversity inNagoya,Japan,in2010.ThreepointsaboutMPAsmustbeconsidered.Thefirstisthequestionofhow

many of the 7,000MPAs actually exist only on paper.AllMPAs start out asideas, andmany are still in the early stages of the process. Inmost cases,weshouldnotjudgetooharshly.Ittakestimetobuildsupportforgoodconservationincommunitiesaswellascountries.ButitiscriticalthatthosepaperMPAsthatarenotyet functioninggetunderway. It takesnotonlyadeterminedeffort toforgeanengagedcommunitybutdedicated funding to implementmanagementplans to ensure that the existing areas become effective. Even more work isrequiredtodesignandimplementthemanymoreMPAsneededtoensuregoodmarineconservation.Secondly,nearly all designatedMPAs todate are located innationalwaters

within 200 nauticalmiles (370 km) of the coast, andmost are within just 12nauticalmiles(22km).That’sthecontentiousareaoftheoceantoday,butasweexploitournationalwatersforoilandgasandtidalandwindpower,expandourrecreationalactivitiesandexhaustourfishstocks,theareaofourconcernmustextendfartherandfartherfromshore.Theocean’sfrontieristhehighseasoutsidenationalwaters,whichmakeup

morethanhalfoftheocean’ssurface.Thisglobalcommons,currentlylargelyafree-for-all, consists of the least protected ecosystems on Earth, saved from

intenseexploitationonlybyrelativeinaccessibility.Yetthehighseasarealreadybeingcrisscrossedbyshippingtraffic,andlinesarebeingdrawnonmapsbyoilandgascompanies,thefishingnationsoftheworldandconservationistswhoarehopeful thatsomepartof theglobalcommonscanbekepthealthy.Atpresent,thereareabout50designatedMPAsonthehighseas,representinglessthanone-fifthof1percentoftheocean’ssurface—atinyfractionofwhatisnecessarytoensureeffectiveprotection.There issomegoodnews too.A legalmechanismforestablishinghigh-seas

MPAs is making its way through the United Nations. Meanwhile, theConventiononBiologicalDiversity is taking the lead inascientificprocess toselect“ecologicallyorbiologicallysignificantareas”(EBSAs),regionbyregion,throughouttheworldocean.TheInternationalUnionforConservationofNature(IUCN) is also proposingmarine Key Biodiversity Areas (KBAs) worldwide.TheInternationalCommitteeonMarineMammalProtectedAreasandtheIUCNMarine Mammal Protected Area Task Force are working with researchersaround the world to help identify marine mammal habitats through a newdesignation:ImportantMarineMammalAreas(IMMAs).Themostextensivepelagicandhigh-seasoceanworktodatehascomefrom

BirdLife International,whichhasmappedover2,000confirmed,proposedandcandidatemarineImportantBirdAreas(IBAs)acrossthebreadthoftheoceans,includingmorethan40high-seasmarineIBAs.Theseincludeseabirdbreedingcolonies, foragingareasaroundbreedingcolonies,nonbreedingconcentrations,migratory bottlenecks and feeding areas for pelagic species. As whales anddolphinsoftenfeedtogetherwithseabirdsneartheoceansurface,somemarineIBAsmayalsobeIMMAs.The Fisheries Centre at the University of British Columbia (UBC) and, in

particular, UBC’s Sea Around Us Project conduct independent research onfisheries and on the wider problems of ocean conservation. In a 2007 paper,fisheries economistRashid Sumaila and his colleagues at the FisheriesCentreanalyzedthecostsandbenefitsofmarinereservesonthehighseas.Theyfoundthatclosing20percentofthehighseastoallfishingwouldmeanalossofonly1.8percentofthefishingcatchandadecreaseinprofitsofabout$270million(U.S.)peryear.Butthebenefitswouldfaroutweighthecosts.AsSumailaandhiscolleagueswrote: “The international communitycouldbenefit substantiallybysecuringinsuranceagainstextinctionsandthelossofthespectacularmarinediversity in the high and deep seas, while protecting many market andnonmarketvaluesforthebenefitofbothcurrentandfuturegenerations.”

Wehaveexploredperhaps1percentofthedeep-sea

Wehaveexploredperhaps1percentofthedeep-searealmandknowlessaboutthespeciestherethanaboutthoseinanyotherhabitatonEarth.Yetdespiteour

ignoranceoftheserichecosystems,‘thethreatstotheircontinuedexistencearenumerousandgrowing.’

In addition to MPA solutions, Barbara Block and her colleagues in theTagging of Pacific Predators (TOPP) project have recommended ecosystem-basedmanagementtoprotectlarge-predatorhabitatwithintheCaliforniaCurrentLargeMarineEcosystem,whichextendsfromthenationalwatersoftheUnitedStates and theMexican PacificCoast into the high seas. TOPP also proposedthataconservationcorridorbeextendedacrosstheNorthPacifictransitionzonetocover“keyecologicalforaginghotspotsandmigratorycorridorsthatlinktheeastern and western Pacific basins for transoceanic migrants. Without anaggressive effort to zone and effectivelymanage these resources, the predatorpopulations they support will decline and the biodiversity of this open-oceanwildernesswillbeirreplaceablylost.”Finally, we should remember that work on marine conservation focuses

mainlyon thewell-studied surfacewatersof the sea andon large, charismaticspecies.Thechampionsofmarineconservationarealmostexclusively,ineffect,focusing on the protection of mammal, bird and fish species living in thetopmostwaters, the skin of the ocean.Even so, the sea bottom is given someconsideration. Since 2004, for example, the Deep Sea Conservation Coalition(DSCC), led by policy advisor Matthew Gianni and others, has worked toaddresstheissueofbottomtrawlingonthehighseas,whichissodestructivetobenthichabitats. In fact, theDSCChassucceeded inobtainingasuccessionofUnitedNationsresolutionsandisworkingtoputthemintobetterpractice.Thisleavesthemiddlewatersbetweenthesurfaceandtheseabed,whichcomprise90percent of the living space on Earth. This vast space is almost completelyneglectedintermsofprotectionmeasures.AccordingtoUniversityofSheffieldmarineecologist andRoyalSocietyResearchFellowThomas J.Webbandhiscolleagues,thedeeppelagicoceanis“biodiversity’sbigwetsecret.”In 2009, Monterey Bay Aquarium Research Institute biologist Bruce H.

Robison alerted the scientific community of the need to thinkmore about theneglectedlayersoftheocean.“Thedeepoceanishometothelargestecosystems

on our planet,” hewrote. “This vast realm containswhatmay be the greatestnumber of animal species, the greatest biomass and the greatest number ofindividualorganismsinthelivingworld.”According toRobison,we have explored perhaps 1 percent of the deep-sea

realmandknowlessaboutthespeciestherethanaboutthoseinanyotherhabitatonEarth.Yetdespiteourignoranceoftheserichecosystems,“thethreatstotheircontinued existence are numerous and growing,” said Robison. “Conservingdeeppelagicbiodiversityisaproblemofglobalproportionsthathasneverbeenaddressed comprehensively. The potential effects of these threats include theextensiverestructuringofentireecosystems,changesinthegeographicalrangesofmanyspecies,large-scaleeliminationoftaxaandadeclineinbiodiversityatallscales.”Robison emphasized the need for baseline studies and carefully designed,

effective MPAs, which have thus far focused on surface waters and benthichabitats.Theboundaries ofMPAs sketchedout on the surfaceof the seamayimply protection that extends to the seafloor, but without amanagement planthat specifically addresses the challenges of mid-to deep-water speciesconservation,theMPAisliterallyonlyskin-deep.Robison’spleacameafterhisownyearsofstudytounderstand“theplanet’s

largest animal communities, composed of creatures adapted to a fluid, three-dimensionalworldwithoutsolidboundaries.”This isscientificwritingarguingfortheveryfutureofthescientist’swork.Athree-dimensionalapproachtotheprotectionofanecosystemissomething

of a novel concept in a world of largely two-dimensional thinking.Whenweproposea land-basednationalparkoramarine reserve,we rarelyconsider theair above the ground or the sea below the surface. Yet the reality is, oceanconservation must be not only three-but four-dimensional, in that it mustincorporate the element of time aswell. For conservation towork in the everfluidflowingocean,wemusttalkaboutprotectingoceanspeciesandecosystemsaswellastheseasonal,cyclicalandsometimesevenephemeraloceanprocessesthat create the conditions for such abundant, diverse life in the sea. Theseprocessesaretime-dependent.Theystartfromthegreatcurrentsoftheseaandthe ocean fronts and themassive upwellings, driven by force ofwind, currentand geography, that bring small organisms to the surface to feed the greatwhales,andtheyextendtothegreattonguesofwatercrawlingalongthebottomoftheseabeforeeventuallyrisinginthewatercolumn.Thuswhenitcomestooceanconservation,wewoulddowelltoconsiderafour-dimensionalenterprise,withemphasisonthethirdandfourthdimensions.Working with colleagues in several IUCN commissions and task forces, I

have learned much about the inner workings of ocean conservation. Whenconservation solutions are devised, the main focus is on the species that arethreatened, followed by the ecosystems to which they belong. Of course,priorities are needed, and species that are endangered, vulnerable or nearthreatened, according to IUCN Red List ratings, require immediate attention.However, the largest number of species in the ocean, even among suchcomparatively well-known groups as the marine mammals, sits firmly in theIUCN“DataDeficient”category.Thesespeciesdeserveasmuchattentionasthethreatenedcategories, largelybecausewehavesolittle informationaboutthemthatweareunableeventoratethem.There is also thematter of species that the IUCN rates as “LeastConcern.”

They,too,deserveaplaceinthesea.Unlesswecanprotectthehabitatofspeciesinlargelyunaffectedecosystems,wewillneverknowhowtheseecosystemsaremeant to function.Without proactive conservation of these pristine areas, wewill have troublewith restoration ecology in the future for areas that becomeheavily utilized to extract fish, minerals, oil and gas. The first job of awatchmakerpreparingtorepairatimepiece,asEdwardO.Wilsonhassaid,istosave all the pieces and keep them safe. But what if we don’t even know theidentity of all the pieces? Given the huge number of unknown and unnamedspecies in the sea, that’s the situation we’re facing, and we must proactivelyprotectthisunknowndiversity.Theonlywaytodothatisbysettingasideverylarge marine habitats—substantial portions of the sea—and guarding them sothattheyremainasnever-to-be-touchedoceanwilderness.Astheocean’sexpanseissystematicallyexploredandresourcesareextracted,

it’swellpastthetimeforsuchthinkingandplanningtoentertheboardroomsofoil and gas companies and other industries and to become part of discussionswithgovernments,fishingfleetsandtheworld’snavies.Becausepiecebypiece,aoncepristineoceanisbeingdismantled.

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Twomaturemalekillerwhales(Orcinusorca)surfaceintheshadowofKamchatkavolcanoes.In2013,long-termphotoIDandacousticandhabitatresearchofkillerwhales—partoftheFarEastRussiaOrcaProject(FEROP)foundedbyauthorErichHoyt—ledtotheacceptanceofthesoutheasterncoastal

watersofKamchatkaasanEcologicallyorBiologicallySignificantAreaundertheConventiononBiologicalDiversity.

ThesunglintsofftheprotrudingfrontteethofasurfacingmaleBaird’sbeakedwhale(Berardiusbairdii).ARussianresearchteam,sponsoredbyWhaleandDolphinConservation(WDC)andledbyauthorErichHoyt,isconductingthefirstin-depthstudyofthesocialstructureofBaird’sbeakedwhalesintheirdeep-waterhabitatintheCommanderIslandsStateBiosphereReserve,Russia’slargestmarineprotectedarea.

Herventralpouchfullofkrillandwater,afemalebluewhale(Balaenopteramusculus)rollsonhersidetoexpelwaterbeforeswallowinghercatch.BluewhalesintheeasternNorthPacificenjoythebenefitsofmarineprotectedareasthatincludesomeoftheirfeedinghabitatalongthePacificCoast,fromCaliforniatoMexico.In2012,followingeffortsbyWhaleandDolphinConservation(WDC)andotherconservationgroups,specialbluewhalehabitatattheCentralAmericanDomewasdeclaredan“ecologicallyorbiologicallysignificantarea.”

Theseby-the-windsailors(Velellavelella)arejellyfishrelativesthatareoftenblownenmasseintoshallowwaterorontobeaches.Typicallylessthanthreeinches(7.6cm)long,eachV.velellaisahydroidcolonyuntoitself,containinghungrypolypsthatfeedonplanktonandsupporttherestofthecolonial

organism.

T

DecidingontheKindofOceanWeWantorLifeAmongtheJellyfish

HERE IS JUST one problem with Robison’s plea for acceleratingbasic researchandcreatingMPAs, theeffortsbyPaulSnelgroveandWardAppeltanstofindandevaluatemorespecies,andwithWilson’s

commentaboutsavingallthepieces.Partsoftheoceanarebeingdegradedandpulledapartfaster thanwecanstudyorsavethem,muchlesscountthem.Thelife-givingoceanitselfischanging.And,atthesametime,somethingismovinginandtakingover.Soundominous?It’shappening.In the 1950s, at the age of five, I began visiting the seaside on annual

vacationswithmy family. I bodysurfed thewaves,worried aboutwhatmightpinchorbitemytoesunderwater,sidesteppedthejellyfish,layinthesunand,intheevenings,rodeontheamusementparkridesandatefastfoodandicecream.ThelocationwasAtlanticCity,NewJersey,butitcouldhavebeenanynumberofoceanresortsoneithersideoftheAtlanticorthePacific.Morethananythingelse,thefreshsalt-airsmelloftheAtlanticOceanasmy

familynearedthecoastyearafteryear,travelingseveralhundredmilesfromourinlandhome,ledmetomakeafirmresolvethatwhenIbecameanadult,Iwouldnever livefarther thanafreshoceanbreezeandaseagull’scryfromthecoast.Fornearlyallof the40someyearssinceI lefthome, Ihavekept that resolve,livingvariouslyalongtheeastandwestcoastsofCanadaandtheUnitedStatesand inScotland andEngland.During this time,my relationship to the seahasdeepened.WhenIwasn’tlivingandworkinginsomecoastalcommunity,Iwasout on the sea on one of many expeditions to study whales and dolphins inCanada, Russia and Japan. There have been a variety of oceanographyexpeditions, suchasan invigoratingwintercruiseof theNorwegian-GreenlandSeaoneMarchwhen,dayafterday,wehadtobreakthroughmeter-thickice.I

oncecalculated that I hadhappily endureda totalof at least30months at seasincethatfirstsummerstudyingkillerwhalesoffnorthernVancouverIslandinmyearly20s.IhavetraveledfarfrommychildhooddaysattheseasidewhenIwoulddodge

thejellyfishandworryaboutpinchingcrabsorbitingfish.Instead,Iseekoutthepinchers,thebitersand,forthatmatter,thestingers—although,ofcourse,mostseacreaturesposenoharmatalltohumans.Idohavemyfavorites,andItrynottojudgethemasbadorgoodonthebasisofwhethertheyarecapableofcausingnagging or severe pain to humans and even death. Causing harm to theenvironment isadifferentstory.Jellyfisharediverse in theirownlittlenarrowplanktonic world; they have their own supporters. In their own jellyfish way,theycanbewildlyexoticorgaudilybeautiful.Lonejellyfishfloatingthroughthegloomofthemesopelagicordeepseasarebeaconsoflightandlife.Butjellyfishin large numbers choking the sea are, more than any other group of marineanimals,visibleindicationsofproblems—redwarningflagsofserioustrouble.Oneofmygreatpleasuresthesedaysisapocketfieldguideto20,000known

deep-seaspecies,whichIcarrywithmeeverywhere.Containingtheequivalentofthousandsofpages,itisnotabookbutanoff-linephoneappcalledDeepSeaID, developedbyLondon’sNaturalHistoryMuseum. It’s basedon theWorldRegisterofDeep-SeaSpecies (WoRDSS),which is, in turn,partof theWorldRegisterofMarineSpecies(WoRMS)builtbytheCensusofMarineLife.Deep Sea ID puts the deep sea in your pocket—a handy version of the

Encyclopedia of Life that focuses on the deep. It is mainly a resource forresearchersworkinginthefield,labworkerswhoneedfastaccesstotaxonomicinformationandamateurenthusiasts,butanyonecanuse it.By itsverynature,thisfreeappwillneedconstantupdating,butevenadramaticexpansioninthenumberofoceanspecieswillstillbeaccessiblefromasingleapponaphone.LookingmorecloselyatthevastnumberofspeciesrepresentedinDeepSea

ID,Iamastonishedbyhowfewhavebeenphotographed.Atpresent,only350high-resolutionphotographsdepictindividualspecies.The20,000DeepSeaIDentries feature taxonomic information and are neatly classified in evolutionarytrees,butmanylackcompleteprofiles—notonly is thereadearthofphotosorillustrations,buttherearenocommonnamesorspecificdatathatwouldenabledeep-sea enthusiasts who are not also deep-sea specialists to appreciate whattheyarereading.Suchistheadventureoflivingonthefrontiersofknowledge!Turning to the jellyfish pages of Deep Sea ID, I marvel at this creature’s

delicatebeauty,itsdiaphanousmembrane,itselegantthoughsometimesdeadlytentacles(thatfeaturewhichcanbedeeplyalluringtocuriouspredators)anditspassiveyetominouslie-in-waithuntingstrategy.ButIstoptoreflect.Therange

of species included is not great in the totality of the deep sea; it’s a sliver ofwhat’sonoffer.Butwhatiftheseweretheonlypagesinmyapp?Whatifallthenonjellyfish pages simply said “Critically Endangered” or “Extinct” andwereessentiallyofhistoricalinterestasrecordsofanoceanthatoncewas?Researcher Lisa-ann Gershwin has spent a long time thinking and writing

about jellyfish and the current state of the sea. As one of a handful ofworldjellyfish experts, she is in an unusual position: Gershwin is working with amarinespeciesthatisclearlyinitsascendancy.Unlikeabeakedwhalespecialistwhomust travel farout to sea forweeksormonthsata time,exercisinggreatpatienceinthehopethathisspeciesappears,oracolossal-squidauthoritywhomayneverhaveseenhersubjectinthewild,Gershwindoesn’thavetolookfarwhenshegoestowork.Andshewillneverbeoutofwork.Butshedoesn’tseejust jellyfish. Every day in the field, Gershwin notes the evidence of humanimpactonthesea,fromlocaloverfishingtoglobalwarmingatthelargestscale.InherbookStung!OnJellyfishBloomsandtheFutureoftheOcean,shepaintsapicture of wide expanses of the ocean “flipping” to a jellyfish-dominatedecosystem.

TheSargassoSeaCensusofMarineZooplanktoncruisein2006turnedupthisstrangecolonialjellyfishlikesiphonophorefromtheRosaceagenus.Multipleunitscompriseasiphonophore,eachspecializedforafunctionsuchasswimming,feedingorreproduction.Somesiphonophoresgrowverylarge,withtentaclesmeasuringupto164feet(50m)long.

Foundthroughouttheworldocean,themoonjellyfish(Aureliaaurita)sometimesseemstobetakingovertheocean.Itfeedsonplanktonicmollusksandcrustaceans,tunicatelarvae,youngpolychaetes,protozoans,diatoms,fisheggsandothersmallorganisms,aswellasgelatinoushydromedusaeandctenophores.Boththelarvaeandadultshavenematocyst-coveredtentaclestocapturepreyandprotectthemselvesfrompredators.

Ajuvenilemackerelhidingbesidethisjellyfishisabouttoloseitsshelterbecauseofahungrygreenturtle(Cheloniamydas)goingafterthejellyfish.Seaturtlesandotherjellyfishpredatorsareonthedeclinethroughouttheworldocean.

Massivejellyfish“blooms,”saysGershwin,areturningupinagrowingnumberofareas.In2011,UniversityofBritishColumbiamaster’sstudentLucasBrotzexamined data for 45 of the world’s 66 LargeMarine Ecosystems and foundjellyfishonthe increase in31of them.JustasGershwinhas,Brotzdiscoveredstrongcorrelationsbetweenjellyfishbloomsandhumanactivities.Jellyfisharereproducing fast and furiously. In most areas, there are simply fewer of itsnatural predators—loggerhead sea turtles, filefish and various other fish. Butjellyfish don’t have many predators, and in some ways, as Gershwin says,jellyfish themselves can be considered a top predator.That’s because jellyfishpacka“doublewhammy”—theypreyonawidevarietyofothermarinespeciesandoutcompetethemaswell.Theynotonlyeatthepreyoffishbutalsofeedonthefishlarvaethemselves,limitingrecoveryofcommercialorotherfishstocksthat are in trouble. Jellyfish-dominated ocean ecosystemswill be hard to turnaround.“Once jellyfishgaincontrol through thisdoublewhammyofpredationandcompetition,”saysGershwin,“theyareabletokeepcontrol.”What controls jellyfish if not predators? Gershwin explains that control of

jellyfish populations comes mainly from bottom-up forces like temperature,salinity, foodsourcesandavailabilityofspace.Butwithoutpredatorsandwithdiminishing competition from decreasing populations of othermarine species,“jellyfish populations can bloomwithout restraint,” she says. “Because of thejellyfish’s low metabolism, the total biomass of a jellyfish bloom can quitequicklyandeasilyovertakethetotalbiomassofotherspeciesinanecosystem.”Meanwhile, as I write this, jellyfish continue to spread, slowly but surely

winning the battle for space in the sea. Jellyfish grief certainly abounds.Gershwindevotesthreelongappendicesofherbooktodetailincidentsinwhichjellyfisharoundtheworldhavealreadyinterferedwithtrawling,desalinationandpower-plant operations, leading to emergency shutdowns. I witnessed one oftheseinlateJune2011,whentheTornessnuclearpowerstationreactors,afewmiles fromwhere Iwas then living in Scotland, had to be closed down for acouple dayswhen the stationwas literally besieged bymoon jellyfish. It tookfishermenfromthreetrawlerstoclearthewaters.OthereventsatnuclearpowerstationsintheUnitedStates,SouthKorea,Japanandothercountrieshavebeencausedwhenjellyfishhavecloggedthecooling-systemfiltersorseawater-intakepipes,sometimesresultinginplantsbeingshutdownformorethanaweek.While jellyfishmaybean irritationforoceanswimmers,surfersandsailors,

the potential for their unleashing much greater havoc is substantial. Theirpresence can affect the economies of ocean beach communities around theworld,andjellyfishmayalsohaveabigimpactontheworldfoodsupplyandonthefuturehealthofoceanecosystems.

To a greater extent than any other species or group of organisms, jellyfishmoveinwhenthebalanceof theseaisupset,whenthewaterstarts tobecomewarmer and more acidic, when too many fish and other marine species areremovedfromanecosystemandwhenthereislessoxygeninthewater.Intoomany scenarios, jellyfish then proceed to take over, and the few remainingpredatorfishandseaturtlesarenotenoughtostemthetide.Therangeofvariousjellyfishspeciesalreadyextendsfromshallowwaterstothedeepseaanddowndeep through the water column. They can live in warm and cold waters.Throughout the world ocean—make it hotter, colder, more acidic, subject tohigherpressure,withorwithoutlight—therearejellyfishreadytosettleinandcallithome.Even the Antarctic is not safe. During the hydrothermal vent expeditions

along thesubantarcticEastScotiaRidge in2009–2011,AlexRogerspulledupevidenceofplasticpollution inhis samples.At theGlobalOceanCommissiondebateatOxford’sSomervilleCollegeinNovember2013,Rogersspokeaboutthe worrying situation with the ocean: “We are seeing evidence of climatechangeallover theoceans,everywherewego.And this ismanifested in threeways.Oneistemperature,theotherisacidification,andthelastistheloweringofoxygenlevelsinthesea.”Rogers cited a 2013 study in the journalNature Climate Change that had

compiledmore than 1,700 long-term observations of a wide variety of oceanspecies, from algae to polar bears. The resulting paper, ominously entitled“Globalimprintofclimatechangeonmarinelife,”reportsthat80percentofthespeciesstudiedareshiftinginrange,populationandbehavior—plantandanimalplankton have the greatest shifts—and that these shifts are precisely whatscientistshavebeenanticipatingasaresultofclimatechange.Inoneway,itisgoodthatplanktoncangowiththeflow,quiteliterally,movingfarthernorthandsouthtowardthepolesastheseawarms.Butthereisasignificantrepercussion.The timing that brings migrating seabirds, fish and blue whales to feed onzooplanktonmaybeoutofsync.Manyanimalsareonatightschedule.Iftheydon’t gain nutrition and put on weight after their long migrations and beforebreedingorotherlifeevents,theirproductiveyearsandeventheirlivesmaybeover.Someareabletomodifytheirbehavior;otherscannoteasilyadaptandmaybeheadedformuseumsandthefossilrecord.Thingsareshiftingwithin thezooplanktonworld too. In theAntarctic, there

are shrinking krill populations due to overfishing and the reduced habitat foryoungkrillalongtheedgeofthenowmeltingseaice.Thisdeclinehasledtoanecosystem in which populations of copepods are increasing and replacing thekrill. Copepods are key to many food webs around the world, but in the

Antarctic, krill represent the fundamental species. Everything from penguins,seabirds, big fish, seals and the great recovering whale populations of theAntarctic depends on krill. It’s also true that some fish, birds and at least onewhalespecies, therightwhale,prefercopepods,butinthewild,coldwatersoftheAntarctic,aricherfoodsourceisneeded,andkrillaremorethan100timesthesizeandnutritionalcontentofcopepods.ItalsohappensthatAntarcticcopepodsareaperfectdietaryfitforAntarctic

jellyfish.Thejellyfisharearriving,reproducinglikecrazyandspreading.Iftheymanage to dominate the Antarctic ecosystem, the vast penguin and seabirdcolonieswill start to gohungry.Seals and evenwhalesmaybecome lean andeventually emaciated. Some of these species live here year-round, and others,such as the humpback,minke and seiwhales, travel here fromgreat distancesspecifically to eat. A few lean years could change Antarctic seas even moreprofoundly than did the intensivewhaling of themid-20th century that led tocrashesofSouthernOceanfin,blueandotherwhales.Can anything coexistwith jellyfish?Microbes can, of course. In fact, some

archaeanmicrobeswilldowellinthesortofhot,acidicseaswherejellyfishmaypersist.Certainmicrobesarealreadydeveloping relationshipswith jellyfishbyprovidingthemwithlight,awayforthejellyfishtodrawpreyorthetoocuriousintoitstentaclelair.Then there are algae. Gershwin paints the future ocean picture in terms of

speciesvisible to thenakedeye:“Nocoralreefs…nomoremightywhalesorwobblingpenguins.Nolobstersoroysters.Sushiwithoutfish.Intheirplace,weshall see blue-green algae, emerald-green algae, golden algae, flashing bluealgae,redtides,browntidesandjellyfish.Lotsofjellyfish.”What is changing theocean?Actually, it isnot the jellyfishand it’snot the

microbes.Forthemostpart,itisyouandme,notjusthumanswhogotoseaorlivebytheseaorusetheseaasagarbagedump,butallhumanswhodependontheseaforsomeoftheirprotein,theirenergy,theirtransportationandeventheirsenseofwonder.Iftheoceanwereabletoreboundbyreplacingwhatweremove(fish and other species) orwhat is destroyed by industry (habitat for fish andotherspecies),whatwe’redoingmightbeacceptabletosomeextent.Butwearepushing thenaturalcapacityof theocean towithstandour insults, andanothergroupofspecies—thejellyfish—isjumpingintothegapandtakingadvantageoftheseaandofusbecauseofouractionsandinactions.What kind of ocean do we want? Jellyfish to greet us when we go out to

swim, dive, surf, sail, watch whales, catch fish or dine on a seafood platter?Instead of whale-watching tours, jellyfish-watching tours? An ocean full of“jellyfish wonder”? An ocean no longer able to supply food, no longer

productive?Anacidbathnolongerabletoabsorbtheincreasinglevelsofcarbondioxidefromtheatmosphere?Jellyfishsushiandjellyfish-and-chipjointsalongthe beach—is that all the oceanmeans to us?Or dowewant towork for anoceanwithbiologicalmarvelslivinginhealthyecosystemsthatwecanproudlyshowtoourchildrenandtheirchildren?Oneday,wemaybeabletohireasubmarine, likearentalcar,andvisit the

depths.Perhapsthenwewillreallyappreciatewhatit’slikeinthe99percentofthe seawecan’tvisualize.Whenvisitingournearest seaside town,alongwiththelureofswimming,sunbathingandamusementparkrides,theremightbeanopportunityfortheadventuroustotakearealtripunderthesea.Let’shopethatwhen this time comes, there will be more to see than jellyfish. Biodiversitydoesn’tsimplygiveusthemostinterestingocean.Biodiversityequalsahealthyocean.

♦

Movingintotroubledwatersanddisplacingotherorganisms,moonjellyfish(Aureliaaurita)eventuallymakeitdifficultforotherspeciestosurviveandreproduce.

H

Epilogue

OWMANYMOREdeep-seacreatureslurkinandamongtherocksandsedimentsinthetrenchesandinthewatercolumnaboveremote,undiscovered portions of the abyssal hills and plains? Besides the

millions ofmicrobes yet to be found, therewill probably be somemegafaunatoo.Sincewehavestudiedlessthan1percentoftheoceanfloorandevenlessofthewatercolumnfromtheseafloor to thesurface layers,wehavemuchyet tolearn. But no matter how diverse the spectrum of species, we have genes incommonwitheverymarineorganism.Inthisway,wesharethemysteryoflifewithallthecreaturesofthedeep.OnamuchyoungerPlanetEarth,withperhapsasinglerudimentarycontinent,

archaeansandotherprimitivelife-formsmaywellhavearisenonthemarginsofthe superheatedwater surrounding a deep-sea vent. The deep oceanmaywellhavebeentheearliestlaboratory,thefirstprovinggroundforlife.Andsowejourneytothebottomoftheseainsearchofourselvesaswell.I am reclining on the back of a fishing boat northeast of the Dominican

Republic.Iamonawhaletrip,butthewhalesarenowheretobefound,andmythoughts, like this rattling boat, are drifting. The fierce tropical sun fights topenetrate the low haze off the coast. A fewmiles out, themorning sea turnslively,butnotyetuncomfortable.Thecaptainshoutsoutourcoordinates:19°55'N, 65°27'W.We are almost there. I have been waiting for thismoment, themoment when I can say I am directly above the deepest part of the AtlanticOcean: thePuertoRicoTrench,more than fivemiles (8km)deep. It isnotasdeep as Challenger Deep, in the Pacific, but it is less visited and even lessknown.Attheprescribedmoment,thecaptainshutsdowntheengines,andweslideto

aslowrockingstop.Thesoundofthewaveslappingagainstthesidesoftheboatwouldbeenoughtosendmetoapeacefulsiestaonmostdaysinthetropics.Butonthisoccasion,Ican’tchasetheideafrommymindofbeingsoclosetooneof

thedeepestpitsoftheocean.And then it hitsme. Itwould be so easy to be the first person to touch the

bottom here. Unlike a trip to the moon, which costs millions of dollars andrequires years of training, or summitingMount Everest, which demands bothfinancingandmountain-climbingskills,avisittothePuertoRicoTrenchatthismomentwould be simply amatter of tying on a fewweight belts and gentlyrollingoffthedeckoftheboat.Itmighttakeafewhours,butIcouldbeonthebottombysuppertime—thefirsthumantoreachthehadaldepthsunassisted.TheseacucumberswouldgreetmeasIarrived,andwewouldsoonbejoined

bytheoddstarfishandmaybeacrabortwonewtoscience.ThenIwouldstrollalongthesubductionzonewithmylittleentourageandperhapsstumbleupontheremnantsofahotvent.ProddingtheemberswithKingNeptune’sstaff,Icoulduncover new species of mussels, eyeless shrimp and hardy archaeans. Thiswonderful fantasywould be “rapture of the deep,” not at all the condition ofnarcosis to which Cousteau referred—a consequence of diving too deep—buttruerapture.Myfantasyissoonshatteredbytherealityofhowcloseandyethowfarthe

hadaltrenchesremain.Reachingthebottomofthetrenchesiseasy.Thetrickisgettingthereandbacktothesurfacealive.Evenwithsubmarines,thetechnologicalchallengeofgettingtothebottomof

theseahasprovedattimesmoreelusivethanspaceshuttleflights,spacestationvisits and moon landings. It took a great deal of determination for JamesCamerontoachievehisdreamed-ofdescent toChallengerDeep.Butsomeday,wewilldevelopthetechnologynecessaryforhumanstoexplorethemiddleanddeeplayersof thesea, justaswedonowonthesurfaceof theseawithcruiseships.ItcoulddevelopliketheplannedspaceflightsforwhichRichardBransonandothersarealreadysellingtickets.Thedeepisstill the lastfrontier,yetoneday, I believe we will take holidays there, perhaps to escape the heat andhumidityof the city, toget back toour evolutionary roots in the seaor togetawayfromthepressure,asitwere,oflifeatsealevel.For the foreseeable future, however, it is but a journey of the imagination,

informedbyscienceatthefrontiers.Inourimagination,wecanswimorspeedinexorablytothebottomandexploreeverylayer.Withourimagination,wecanrenewthebondwithouroceanicEarthanditsdeep-seacreatures,theseafromwhichourspeciescame.Wecanconsiderourrelationshiptothearchaeans.Wecanlistentothescientistswhotellus thesegreatstories,andinthedecadestocome,thedeepoceancanhelpusrediscoverthemysteriesandunlockthesecretsofourownwaterplanet.Thisistherideofourlifetimefornow,aswewaitfortechnologytogiveustheactualridetothebottom.

Then,disruptingmyreveries,asinglejellyfish, idlyridingthecurrent,driftsintoview.Atfirst,itisjustone.Itridesthewavesboldly,displayingitscolors.Butbehindit,Iseeawholeflotillaofjellyfish.Andminuteslater,downbelow,jellyfish are illuminated in the water column. They are all the same, like anadvancingarmy—mindless,relentlessand,finally,menacing.Arethesethetruemonstersofthesea?Onethingforsure,ifthejellyfishdotakeovertheocean,the traditional“monsters” thatweallknowandlove, fromsharksandsquid towhales,willbeconsignedtothemargins,ifnotthescrapheap,atthebottomofthesea,tobecomepartoftheooze.Thegreateraofcreaturesofthedeepwillbemostlyover.Within10minutes,thejelliesareallgone,carriedawaybythecurrenttodo

theirbusinesselsewhere.Atthesametime,thestrainsofanancientmelody,anorchestraofcellostestingthevibratoontheloweststring,filterupthroughthewater and the underside of this resonant wooden boat, like the strains of afamiliarsong:thesweetestsongofthedeepbluesea.Amassive femalehumpbackwhale adornedwith aheavycropofbarnacles

chargesupfromthedeepblackandintostreakyblueview,smashingtherippledsurface.Rearingherhead,sheshootsherblowskyward,drenchingallofusandsuckinginabiteofatmospherebeforedippingbelow.There’sscarcelytimetocatchahumanbreath.Halfaminutelater,sheemerges,allofher,allatonce,astone’sthrowfromtheboat—afullbodybreachofinstantjoy.Now,that’smyocean.

♦

Inaleaping,flyingexpressionofpureexhilaration,ahumpbackwhale(Megapteranovaeangliae)seizesthemoment.

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AuthorBiography

ErichHoythasspentmostofhis lifeonornear thesea,workingwithwhales

anddolphinstolearnabouttheirdailylivesandtoprotecttheirhabitat.Hehaswrittenbooksonmarinewildlife,ants,insects,protectedareasandothernaturalhistorysubjects.CurrentlyaResearchFellowwithWhaleandDolphinConservation(WDC)in

England, Hoyt leads theWDCGlobal Critical Habitat/Marine Protected AreaProgramme.Healsoco-directstheFarEastRussiaOrcaProjectinKamchatka.HoytisamemberoftheInternationalUnionforConservationofNature(IUCN)Species Survival Commission’s Cetacean Specialist Group and co-chairs theIUCNMarineMammal ProtectedAreasTask Force.He has been aVannevarBush(KnightScience)FellowattheMassachusettsInstituteofTechnologyandhastwicebeennamedasaThurberHouseWriter-in-Residence.Hoytistheauthorofmorethan20books,includingOrca:TheWhaleCalled

Killer. His work has been translated into 15 languages and published in 25countries. The first edition of Creatures of the Deep won the OutstandingNonfiction Book of the Year Award for 2001 from the American Society ofJournalistsandAuthors.In2013,hereceivedtheMandyMcMathConservationAward from the European Cetacean Society for his body of work on marineconservation.Hoyt lives in England with his wife SarahWedden, a biomedical research

scientist,andtheirchildrenMoses,Maddie,JasmineandMax.

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