traveling treasures 2016 – the power of poison
TRANSCRIPT
TravelingTreasures2016–ThePowerofPoisonSnakeandButterflycaseTimberrattlesnake(Crotalushorridus)
Lightmorph
LikeothersnakesinthefamilyViperidae,timberrattlersarepitvipers.Thismeanstheyhaveheatsensitivepitorganslocatedbetweenthenostrilsandtheeyes.Theyaresensitivetoradiantenergyandcandistinguishveryslightchangesintemperature.Theirmainfoodsourceissmallmammalsbutalsoeatbirds.Thepreyiskilledwhenbittenbecausethesnakeinjectsvenom.Theythenswallowthepreywhole.
RangeandHabitat:TimberandcanebrakerattlesnakeshaveawidedistributionintheeasternUnitedStatesbutthespeciesisabsentfrommostofFlorida.Thissnakeoccursinawidevarietyofterrestrialhabitatincludinglowlandcanethickets,high
areasaroundswampsandriverfloodplains,hardwoodandpineforests,mountainousareas,andruralhabitatsinfarmingareas.Theytypicallybecomereducedinnumbersinhighlyurbanizedorareasofhousingdevelopment.
TheOrianneSocietyTimberRattlesnakeFactSheethttp://www.oriannesociety.org/sites/default/files/fact-sheets/Timber%20Rattlesnake%20Fact%20Sheet.pdfFirsthandaccountofaTimberRattlesnakebite:http://www.venomousreptiles.org/articles/345?venomsid=f065e3fa57ac4a0dabcdb000f3c3b09cBandedkrait(Bungarusfasciatus)
Habitat:Livesinandaroundwetlands,openforests,agriculturallandshavinglow
vegetationandopenwaterbodiesetc.Strictlypreferswetsurroundingforits
activities.Usuallyfoundinplainsoflowtomoderateelevationsbutinmanypartsof
itsrangeitsfoundinelevationupto5000ft.
Snakevenomscontainamultitudeofbiologicallyactivetoxinsthatworktogetherforthecaptureofprey(takealookattheTablelistingthevarietyoftoxinsfoundinthevenomofthemany-bandedkrait).Theireffectsincludepro-andanti-bloodcoagulation,neurotoxicity,mycotoxicity,nephrotoxicity,cardiotoxicityandnecrotoxicity(localtissuedamage).Amongstthese,theneurotoxinsplayakeyroleinimmobilisingpreythroughparalysis,disorientationanddepressedrespiration.
Venomsoftencontaindifferentneurotoxinsthatworksynergisticallytocripplethenervoussystem.Neurotoxinscanbeclassifiedaccordingtotheirsiteofaction:pre-synapticneurotoxinsblockneurotransmissionbyaffectingacetylcholinetransmitterrelease;post-synapticneurotoxinsareantagonistsoftheacetylcholinereceptor.Togethertheseneurotoxinseffectivelyblockskeletalneuromusculartransmissionbycripplingreceptors,whileatthesametimeactingtodestroyanyneurotransmitterthatmightcompetewiththetoxinforreceptorbinding.Venomsoftencontainseveralpost-synapticneurotoxins,eachwithahighaffinityforanicotinicreceptorsubtype-inthiswaythevenomcancrippleasmanyreceptorsaspossible.Thepost-synapticneurotoxinsarefoundonlyinelapidsandseasnakes(Hydrophiidae).Inthemany-bandedkraitpicturedabove,apre-synaptictoxinisb-bungarotoxin,whilepost-synaptictoxinsarea-andk-bungarotoxins.
CentralAmericancoralsnake(Micrurusnigrocintus)
It ranges from southern Mexico through Central America (except Belize) to northwestern Colombia, and the westCaribbean. It is mainly found in lowland rain forest, lowland dry forest, thorn forest, lower montane wet (or moist) forest, and lower montane dry forest, usually at elevations up to 1,300m.[1] The Central American coral snake's venom contains a strong neurotoxin, causing neuromuscular dysfunction.[1]Coralsnakesaresmall,vibrantlycolored,highlyvenomoussnakes.Theyhavethesecond-strongestvenomofanysnake(theblackmambahasthemostdeadlyvenom),buttheyaregenerallyconsideredlessdangerousthanrattlesnakesbecausecoralsnakeshavealesseffectivepoison-deliverysystem.
Hasmainlypotentneurotoxicvenomwhichcanbeinjectedthroughapairofgrooved,upper,fixedfrontfangs.Duetothesmallsizeoftheirmouths,coralsnakebitestohumansusuallyoccuronafingerortoe,andusuallyduringattemptstocatchthesnake.Thisspeciesisabundantthroughoutmostofitsrange,andisthemaincauseofcoralsnakebitesofhumanswithinitsrange.Monarchbutterfly(Danausplexippus)Butterflyidentificationchart:
MonarchbutterfliesareknownfortheincrediblemassmigrationthatbringsmillionsofthemtoCaliforniaandMexicoeachwinter.NorthAmericanmonarchsaretheonlybutterfliesthatmakesuchamassivejourney—upto3,000miles(4,828kilometers).Theinsectsmustbeginthisjourneyeachfallaheadofcoldweather,whichwillkillthemiftheytarrytoolong.Fatteninglarvaebecomejuicy,colorfulcaterpillars,thencreateahardprotectivecasearoundthemselvesastheyenterthepupastage.Theyemergeasbeautifully
colored,black-orange-and-whiteadults.Thecolorfulpatternmakesmonarchseasytoidentify—andthat'stheidea.Thedistinctivepatternwarnspredatorsthattheinsectsarefoultastingandpoisonous.
Butterfliesthatemergefromchrysalides(pupastate)inlatesummerandearlyfallaredifferentfromthosethatdosoduringthelongerdaysandwarmerweatherofsummer.Thesemonarchsareborntofly,andknowbecauseofthechangingweatherthattheymustpreparefortheirlengthyjourney.
Onlymonarchsborninlatesummerorearlyfallmakethemigration,andtheymakeonlyoneroundtrip.Bythetimenextyear'swintermigrationbegins,severalsummergenerationswillhavelivedanddiedanditwillbelastyear'smigrators'greatgrandchildrenthatmakethetrip.Yetsomehowthesenewgenerationsknowtheway,andfollowthesameroutestheirancestorstook—sometimesevenreturningtothesametree.
It’sthedependencythatMonarchshaveonMilkweedsastheonlyfoodsourcefortheircaterpillarsthatmakesthisrelationshipsonoteworthy.Monarchs,likemanyspeciesofinsects,haveevolvedtospecializeintheirlarval(inthiscasecaterpillar)foodsourceinordertogainprotectionfrompredatorsthroughthechemicalstheyingestfromtheplantstheyeat.Milkweedscontaincardiacglycosides,whicharetoxictomanyspeciesofbirdsandmammals.Plantshaveevolvedthesechemicalstoprotectthemselvesfrombeingeaten,astrategythathaslargelybeensuccessfulfortheplants.Plantsareallaboutsurvivingandreproducing,tofurtherthecontinuedexistenceoftheirspecies.
Suchaplanforprotectionisnevercompletelyfoolproof,however.Monarchs,alongwithsomeotherinsectspecies,haveevolvedtobeabletodigesttheseplantsandsequesterthetoxinsintheirbodies,makingtheinsectunpalatableatbestandtoxicatworsttoanyoneinexperiencedenoughtoattempttoeatthem.Asaremindertobirdormammalpredatorswhosamplesuchaninsectandsurvivetoeatanothermeal,insectswiththesetoxinshavealsoevolvedtohavebrightwarningcolors,aneasytoremembersignaltopredatorstobewarebeforeattemptingsuchamealagain.InexchangeforthisprotectionobtainedfromeatingMilkweeds,Monarchsaregamblingthatthisfoodsourcewillcontinuetobeavailable.Withoutit,Monarchswon’tsurvive.