1OUR OCEAN PLANET

OUR OCEAN PLANET

SECTION 6 – TEMPERATE SEAS

2REVISION HISTORY

Date Version Revised By Description

Aug 25, 2010 0.0 VL Original

36. TEMPERATE SEAS

6. TEMPERATE SEAS

46. TEMPERATE SEASTemperate seas lie between the tropics and the polar regions. These are cool green waters that are highly productive and immensely rich in algae, plant, and animal life.

Summers are warm and winters cold but there is rarely permanent sea ice in temperate waters. Water temperatures range from 4°C-20°C (39°F-68°F).

The algae and plant life that makes these seas green comes from chlorophyll found in several organisms namely:

1. Plankton Phytoplankton – plant and algae plankton Zooplankton – animal plankton2. Marine Algae/Seaweeds Green Brown Red

The rich algae and plant life base gives rise to large numbers of zooplankton (e.g. copepods), herbivorous invertebrates (such as sea urchins and molluscs), and herbivorous fish. These primary consumers are preyed upon by other invertebrates (e.g. jellyfish, horseshoe crabs), fishes (e.g. sturgeons), birds, and mammals (e.g. sea otters and sea lions).

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6.1 PLANKTON

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6.1 PLANKTONPlankton is a general term used to refer to a variety of tiny animals and plants that are found drifting about in the ocean.

There are two main types of plankton, namely, phytoplankton (plant plankton) and zooplankton (animal plankton). They are usually microscopic in size although some can be quite large (a couple of meters in diameter).

Each year, between spring and autumn, plankton numbers increase dramatically to form huge populations. These planktonic blooms are critical to vast numbers of invertebrates, fish, birds and mammals, since plankton is one of the most fundamental and important sources of food in the ocean.

6.1.1 PhytoplanktonPhytoplankton (plant plankton) can use sunlight to transform carbon dioxide and water into carbohydrates through a process called photosynthesis. Phytoplankton are, therefore, producers and form the base of the ocean’s food chain.

There are several types of phytoplankton varying greatly in size and shape:

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1. CyanobacteriaCyanobacteria are the smallest of the phytoplankton and are tiny single-celled organisms that have blue and green pigments. This gives them their common name – the blue-green bacteria or blue-green algae.

2. DiatomsDiatoms are beautiful single-celled algae with two glass-like halves and spines and ribs radiating from them. There are over 6,000 species of diatoms, and they are often the most numerous phytoplankton in temperate waters.

3. DinoflagellatesThe dinoflagellates have both plant and animal characteristics in that they are able to photosynthesize food (like plants) but can also move using flagella (like animals). Their bodies are made of cellulose and they can produce bioluminescent light.

4. ProtozoansProtozoans are single-celled animals. However, some protozoans contain symbiotic algae which are able to photosynthesize food. Protozoans such as foramniferans have shells made of calcium carbonate while radiolarians have shells made of silica.

Important!Each year, 6 billion tonnes of microscopic algae, such as diatoms, grow in the world’s oceans producing nearly 50% of the world’s oxygen – a by-product of photosynthesis.

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REFERENCES & FURTHER READINGByatt, Andrew, Fothergill, Alastair and Holmes, Martha, The Blue Planet: Seas of Life, Chapter 4, DK Publishing Inc., (2001), ISBN 0-7894-8265-7

Interesting!The word plankton comes from the Greek word “planktos” which means “drifter” or “wanderer”.

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6.1.2 ZooplanktonZooplankton (animal plankton) feed on phytoplankton or other zooplankton. There are several types of zooplankton, namely:

1. CopepodsCopepods ("oar feet") are small, shrimp-like crustaceans with T-shaped antennae that swim in seas, lakes and ponds. These are the primary consumers of phytoplankton. They have a hard exoskeleton, legs for swimming and gathering food, a segmented body, and jointed appendages. Most copepods are less than 1 mm (0.04 in) long but a few oceanic species are over 1 cm (0.25 in) long. These arthropods have one simple eye in the middle of the head which can only differentiate between light and dark. There are two pairs of antennae; one pair is long and one pair is short. Female copepods produce clusters of eggs that she carries in one or two egg sacs that are attached to her abdomen. Like all crustaceans, copepods molt their exoskeleton as they grow. There are 10 orders and over 4,500 species of copepod. A few orders are free-swimming (using their legs) but many are parasites (of fish).

Copepods are adept at catching and eating phytoplankton including cyanobacteria, diatoms and other tiny, single-celled organisms in the water. Maxillae, maxillipeds and antennae push food towards the mandibles (jaws) for processing.

Important!Copepods are probably the most numerous animal on the planet forming 70% of the total zooplankton.

Interesting!The collective name for a group of plankton is a “swarm”.

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Free-swimming copepods are a component of zooplankton and are very important in the food web since many animals feed on them including mussels, fish and fish larvae, squid, sea birds, and mammals (such as baleen whales and certain seals).

2. MeroplanktonMeroplankton is the collective name for the tiny eggs and larvae of animals that spend part of their life in the plankton before maturing. In summer, the sea will be full of eggs, larvae and young invertebrates. The young of crustaceans (e.g. crabs, lobsters & shrimps), echinoderms (sea urchins & sea stars), molluscs, and fish are among the huge variety of organisms that spend their first weeks of life as plankton. Many meroplankton are herbivores. In time, they will change in appearance and, if the larvae are fortunate, they will survive to adulthood.

3. Cnidarian LarvaeOther zooplankton include free-swimming cnidarians such as jellyfish. For example, moon jellyfish primarily feed on copepods and can consume thousands in a day. These jellyfish form swarms so dense that the water can appear pinkish-white from the air. In contrast, lion’s mane jellyfish feed on copepods, meroplankton, other jellyfish, and fish, but do not tend to form swarms.

Zooplankton is, in turn, preyed upon by other animals, ranging from other invertebrates and small fish to the giants including planktivorous sharks (e.g. whale and basking sharks) and baleen whales (e.g. humpback and blue whales).REFERENCES & FURTHER READINGhttp://museumvictoria.com.au/crust/copbiol.html - Copepodshttp://en.wikipedia.org/wiki/Plankton - Planktonhttp://www.enchantedlearning.com/subjects/invertebrates/crustacean/Copepod.shtml - Copepods

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6.2 MARINE ALGAE / SEAWEED

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6.2 MARINE ALGAE / SEAWEEDSeaweeds are marine algae and, although they are found virtually worldwide, most of the world’s 10,000 species of seaweed exist in temperate water. The smallest can be planktonic or found growing in sand or inside an animal’s shell or body. The most familiar, however, are probably the large seaweeds which are often found on rocky coasts firmly attached to a hard stable substrate.At the base of the seaweed is a clump of entwined growths, called a holdfast, which anchors the seaweed to the substrate. From the holdfast, a long stem called a stipe extends upwards which supports a series of leaf-like fronds (or “blades”) in which most photosynthesis occurs. In the largest seaweeds, the fronds are buoyed by gas-filled bladders called pneumatocysts. The specific colours and forms of seaweed depend on their habitats and combination of pigments. Generally, however, there are three types of marine algae – green, brown and red.1. Green AlgaeGreen algae get their colour from the green pigment chlorophyll. They are about 6,000 species of green algae but most are not found in the ocean. The marine species are commonly found in temperate rock-pools. They are generally small and many are filamentous resembling thin green hair. One of the most common is sea lettuce, which is found in rock-pools and around the bases of larger seaweeds. Sea lettuce is often eaten by small invertebrates.

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2. Brown AlgaeThere are about 1,500 species of brown algae varying from yellowish to deep brown. They range from simple filamentous algae to the largest seaweed of all – the giant kelp (Macrocystis spp.) which may grow to more than 45 m (150 ft) in length. Although giant kelp superficially resembles a tree, it is quite different. For example, kelp has no roots. Kelp does anchor itself to the bottom of the ocean floor but the anchoring system (“holdfast”) does not take in nutrients from the soil like plant roots do. The stipe and blades of the kelp are very flexible and cannot stand upright unaided. As a result, kelp has tiny air bladders at the base of each blade to help it float and grow toward the surface of the water where sunlight is most plentiful.

3. Red AlgaeRed algae are the most numerous of the marine algae and consist of about 4,000 species. They contain chlorophyll but the green colour is masked by a red pigment called phycobilin. They are usually small and tissue-like, and encrust rock pools or grow on larger brown seaweed stipes. They can be a variety of colours from pink to purple. Some red algae deposit thick calcium carbonate (the same material coral is made from) around their cells walls. These coralline red algae are tough enough to grow in the rocky surf zone.

Interesting!Seaweed is an integral part of human life. Kelp, sea lettuces and red algae are dried, steamed, and cooked in a variety of dishes. The thin black sheets covering rice and raw fish in sushi is made from red algae Porphyra. Alginates from brown seaweed are used to give ice cream its smooth texture. Agar, from red algae, is used in cake icings, as a clarifying agent for beer and as a growth medium for micro-organisms studied by scientists.

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6.2.1 Kelp ForestsKelp provides the physical substrate and habitat around which kelp forest communities are built. Organisms supported by kelp forests include sea urchins, sea stars, sea anemones, clams, and tunicates. These organisms are preyed upon by larger animals such as fish and octopuses. Sea otters and sea lions also eat sea urchins, clams and octopuses. These mammals may, in turn, be preyed upon by large sharks, such as the great white shark.

Kelp forest ecology studies focus on understanding bottom-up and top-down trophic processes – the relationships between organisms and their place in the food chain.

Bottom-up processes are generally driven by abiotic conditions required for primary producers to grow (such as the availability of light and nutrients). For example, the occurrence of kelp is frequently related to oceanic upwelling zones which provide unusually high concentrations of nutrients to the local environment. This allows kelp to grow and support herbivores which, in turn, support consumers at higher trophic levels.

In contrast, top-down processes are those in which predators limit lower level prey species through feeding on them. In the absence of predation, the lower level species would flourish. For example, in Alaskan kelp forests, sea otters control populations of herbivorous sea urchins through predation. When sea otters are removed from the ecosystem (for example, by human activity), sea urchin populations are released from predatory control and grow dramatically. This leads to increased herbivore pressure on local kelp stands.

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Deterioration of the kelp itself results in the loss of the physical ecosystem structure and subsequently, the loss of other species associated with this habitat. In Alaskan kelp forest ecosystems, sea otters are the keystone species that mediate this trophic cascade. In Southern California, kelp forests persist without sea otters and the control of herbivorous sea urchins is instead mediated by other predators including lobsters and large fishes. The effect of removing one predatory species in this system differs from Alaska because there are other predators that can continue to regulate sea urchins. However, the removal of multiple predators can effectively release sea urchins from predator pressure and allow kelp forest degradation. While sea urchins are usually the dominant herbivore, others include sea stars, isopods, kelp crabs, and herbivorous fishes. In many cases, these organisms feed on kelp that has been dislodged from substrate and drifts near the ocean floor. If there is enough drift kelp, herbivorous grazers do not exert pressure on attached plants. Many studies in Southern California have demonstrated that the availability of drift kelp specifically influences the foraging behavior of sea urchins. Drift kelp and kelp-derived particulate matter have also been important in subsidizing adjacent habitats, such as sandy beaches and the rocky inter-tidal areas.

REFERENCES & FURTHER READINGhttp://www.nmnh.si.edu/botany/projects/algae/classification.htm - Algaehttp://www.usc.edu/org/seagrant/Education/Kelp/WhatIs.html - What is kelp?http://en.wikipedia.org/wiki/Kelp_forest - Kelp foresthttp://www.amonline.net.au/factsheets/kelp.htm - Kelp fact sheethttp://news.nationalgeographic.com/news/2006/09/060906-octopus-video.html - octopus/sharkByatt, Andrew, Fothergill, Alastair and Holmes, Martha, The Blue Planet: Seas of Life, Chapter 4, DK Publishing Inc., (2001), ISBN 0-7894-8265-7

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6.2.2 Kelp Forest Life

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KELPKelp is a brown seaweed. Perhaps the most widely-recognized species are the giant kelps (Macrocystis spp.) although there are numerous other types. Macrocystis pyrifera grows to over 45 m (150 ft) long. The stipes (or stems) are unbranched and each has a gas bladder at its base. When a large number of giant kelp grows together, as they do off the coast of California, they are collectively known as a “kelp forest”.

SEA OTTERSea otters are long, sleek and furry marine mammals. They are the largest member of the weasel family and are about 1.2-1.5 m (4-5 ft) in length and weigh 20-45 kg (45-100 lbs). Sea otters have webbed hind feet and smaller front feet. They eat a variety of invertebrates including crustaceans (crabs, lobsters and shrimps), bivalves (clams, mussels and abalone) and echinoderms (sea urchins and sea stars). They also eat octopus, squid and fish. Underneath each front arm is a pouch of loose skin that temporarily stores food and rocks collected during dives. Floating on their backs, sea otters rinse and hammer open prey with a rock they keep in their pouch. They are the only mammal (besides primates) known to use tools.

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CALIFORNIA SEA LIONCalifornia sea lions have a pair of small external ears. They swim using their fore-flippers like oars while their hind flippers are not used. On land, their hind flippers can be turned forward under body and used for movement. There are about 160,000 California sea lions and they are found off the coasts of California, Mexico and the Galapagos islands. They eat fish and molluscs (e.g. octopus and squid).

GREAT WHITE SHARKThe great white shark is considered a large and dangerous shark. They spend much of their life in the open ocean but will move into coastal waters seasonally to hunt for sea lions and seals. It has a heavy body, large head, and pointed snout, with large triangular teeth with serrated edges. Its body is slate blue or leaden grey above and dirty white below. It can reach a length of 7.9 m (26 ft) but is usually less than 4.9 m (16 ft). The great white shark is a member of the Mackerel Shark family and was probably made infamous through the movie “Jaws”.

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OCTOPUSThe octopus is a cephalopod (an unshelled mollusc) that inhabits several different ocean habitats. Octopuses are characterized by their eight arms (not tentacles) which usually have suction cups on them. Unlike most other cephalopods, the majority of octopuses have almost entirely soft bodies with no internal skeleton. They have neither a protective outer shell (like the nautilus) nor any vestige of an internal shell or bones, (like cuttlefish or squids). A beak, similar in shape to a parrot's beak, is the only hard part of their body. As a result, an octopus can squeeze between narrow crevices. This is very useful when it is hiding from morays or other predators.

SEA ANEMONESea anemones are simple animals (cnidarians) that are often attached to the sea bottom. Sea anemones have cylindrical bodies that are surrounded by upward-facing tentacles. The tentacles have stinging cells on them which kill prey and move the food into a sea anemone’s mouth. The mouth leads into the body cavity which digests the food. A continuous current of water through the mouth circulates through the body cavity and removes waste. Sea anemones are found in cold and warm waters. Many are colourful, and large species can be 1 m (3 ft) in diameter.

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SEA STARSea stars (or starfish) are soft-bodied marine animals with five arms. Sea stars are echinoderms, a large group of invertebrates which include sea urchins, sand dollars, sea cucumbers and brittle stars. Sea stars typically live in the middle of a tidal range and can survive short periods of exposure to air as the tide retreats.

SEA URCHINSea urchins are echinoderms. They are round, spiny and herbivorous invertebrates that graze on algae and detritus from grass beds and rocky areas. Many sea urchins have long, sharp spines on their backs, which protect them from predators such as fish, crabs, moray eels and sea otters. However, their underside is often spineless and they are vulnerable to attack from that side if the predator can turn the sea urchin over.

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6.3 OCEAN LIFE

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6.3.1 Horseshoe Crabs

DESCRIPTIONHorseshoe crabs are an ancient species of invertebrates related to the trilobites. They are regarded as living fossils since they have stayed unchanged for more than 350 million years. Horseshoe crabs are not, in fact, true crabs (crustaceans) and are more closely related to spiders & scorpions (arachnids).

CHARACTERISTICSHorseshoe crabs have a hard chitin-based exoskeleton with 3 segments – prosoma (head), opisthosoma (abdomen) and telson (tail). They have 10 eyes, 5 pairs of jointed, pincered, walking legs and 1 pair of feeding pincers (chelicerae). They have light-blue, copper-based blood and breathe through “book gills” (thin plates located on abdomen).

SIZEMales are 18-23 cm (7-9 in) across the prosoma and 33-41 cm (13-16 in) in length (head to tip of tail). Females are typically 30% larger than males and are 23-31 cm (9-12 in) across the prosoma & 41-51 cm (16-20 in) in length (head to tip of tail).

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LIFESPANHorseshoe crabs take 8-10 years to reach adulthood and their lifespan is 20-30 years.

DIETHorseshoe crabs eat worms, mollusks and dead fish. They find prey along the sea bed and use their chelicerae to find & push food into their mouths.

REPRODUCTIONIn winter, horseshoe crabs move offshore and hibernate half-buried in ocean sediments. In spring, they move towards beaches to reproduce. A male hooks onto a female using his first pair of walking legs (“pedipalps”) & remains attached to her. The female then scoops out a shallow nest in the sand and lays 3,000 to 20,000 small jade-green eggs about 20 cm (8 in) into the sand. The male then fertilizes the eggs as she drags him over them. Young horseshoe crabs hatch in about 1 month. The mating season lasts from April through December.

DISTRIBUTIONHorseshoe crabs are found off the coasts of Japan, Hong Kong, Indonesia, the eastern USA (e.g. ME, NY, NJ & DE) and the Gulf of Mexico.

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USESHorseshoe crabs have several uses in medicine. An extract of horseshoe crab blood – Limulus amoebocyte lysate (LAL) – is used to ensure biomedical products (e.g. vaccines) are free of bacterial contamination. Horseshoe crab chitin is used in manufacturing chitin-coated suturing filament and wound dressing for burn victims.

THREATSHorseshoe crabs are threatened by shoreline development and habitat loss, pollution, their use as bait by conch & eel fisheries, and for their blood and chitin by the biomedical industry.

SPECIESToday, there are 4 species worldwide. Limulus polyphemus is found in the Northwest Atlantic Ocean, the other three are found in the Far East.

INTERESTING FACTSHave light-blue, copper-based blood (unlike humans, which have red, iron-based blood)Very important animals from a human perspective as they have several uses in medicineHost to numerous parasites – barnacles, blue mussels, slipper shells, bryozoans, & sponges

Although horseshoe crabs look formidable, they are harmless and do not use their pointed tail as a weapon but only to right themselves when they are turned over.

Horseshoe crabs are not true crabs – actually quite different in spite of general resemblance

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Horseshoe Crabs True Crabs

No antennaeNo mandiblesMultiple un-stalked eyesMoult by walking forward out of their shell

Have antennae1 pair of mandiblesStalked eyesTrue crabs back out of their shell when malting

12 legs (6 pairs) including 6 pairs of claws:1st pair (chelicerae) – for feeding2nd pair (pedipalps) – differentiate genderRemaining pairs are walking legs

10 legs (5 pairs) including 1 pair of claws

REFERENCES & FURTHER READING

http://www.horseshoecrab.org/

All about the horseshoe crab: natural history, anatomy, conservation & current research

http://www.ocean.udel.edu/horseshoecrab/index.html

University of Delaware Sea Grant College Program

http://www.dnr.state.md.us/education/horseshoecrab/

Maryland Department of Natural Resources

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6.3.2 Sturgeons

DESCRIPTION Large, primitive, bony fish Skeleton has large proportion of cartilage Head bony Long snout with a row of 4 barbels in front of mouth Mouth ventral and protrusible Adults have no teeth May have a spiracle above and behind eye 1 dorsal fin set far back Large bony plates (“scutes”) on body Heterocercal caudal fin (upper lobe longer than lower lobe) Long lived – 50–100 years Can take many years to mature–6-25 years depending on speciesSIZETo 6.1 m (20 ft) and more than 1,134 kg (2,500 lbs)SWIMMINGSwim with their caudal fin (tail) and form an “S” shape with their body and tailIsinglass – a gelatinous semi-transparent substance obtained by cleaning and drying the swim bladders of the sturgeon, cod and other fishes. It is used in the clarification of wines & beers and in glues & adhesives.

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SCALESFive rows of large bony plates (“scutes”) on body; (1 on back, 1 at middle of each side and 1 on each side of belly)Scutes better developed in young, virtually disappear in old individualsSkin between scute rows covered with smaller bony scales

TEETH Adults are toothless

DIETBarbels used to help detect bottom-dwelling preySlurp up prey with their protrusible mouthFeed on bottom-dwelling organisms – worms, mollusks & crustaceans

BREEDING & REPRODUCTIONAll sturgeons spawn in freshwaterSturgeon eggs/roe are highly valued as “caviar”Several species are anadromous (spending much of their life in the sea but moving to fresh water to spawn)

DISTRIBUTIONFound in rivers, lakes, bays and estuariesNorthern hemisphere – North America, Europe, Russia (Caspian Sea, Black Sea), Asia

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CAVIAR“Caviar” refers to the processed, salted eggs/roe of certain species of fish, most notably the sturgeon. Sturgeon caviar or true caviar is sold worldwide as a delicacy, and is usually eaten by itself or spread on toast or blinis (small, yeast-raised Russian buckwheat pancakes). Sturgeon eggs are round and vary in size from very small to pea-sized. Their colour can be off-white, gold, light grey, charcoal grey, or black.

Most of the world’s caviar today comes from sturgeons in the Caspian Sea, which is ringed by Azerbaijan, Iran, Russia, Turkmenistan, and Kazakhstan. The rarest and most expensive are marketed as Beluga, Ossetra, and Sevruga caviar, which come from the Great Sturgeon (Huso huso), Russian Sturgeon (Acipenser gueldenstaedtii) and Stellate Sturgeon (Acipenser stellatus) respectively.

Interestingly, the U.S. also had a history in caviar production. For most of the 19th century, the U.S. was the main producer of the world's caviar. Caviar was actually given away free with beer in saloons for the same reason salty peanuts are given away today. By 1910, however, lake sturgeons were so over-fished they were nearly extinct and American production was stopped. In 1925, the Caspian Sea fisheries began the commercial production we know today. Today, American caviar is mainly farmed and typically comes from the White Sturgeon (Acipenser transmontanus), Lake Sturgeon (Acipenser fulvescens) and Shovelnose Sturgeon (Scaphiryhnchus platoryhnchus).

The market demand and commercial value of caviar has resulted in the serious decline in sturgeon numbers worldwide, especially those from the Caspian Sea. Sturgeons take many years to attain maturity and the female sturgeon is killed in the process of extracting the eggs. Thus, in spite of some protection and alleviation of demand through sturgeon farming, most sturgeon species remain threatened or endangered.

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CLASSIFICATION

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STURGEON SPECIES

1. ATLANTIC STURGEON–ACIPENSER OXYRHYNCHUSLong snout, sharply V-shaped and upturnedViscera paleLabrador to Florida and N.E. Gulf of MexicoMostly in shallow waters of continental shelfEnters larger rivers to spawnCommercially important; seriously depletedTo 3.1 m (10 ft) in length

2. SHORTNOSE STURGEON–ACIPENSER BREVIROSTRUMShort snout, not upturned at tipShort barbelsViscera blackishNew Brunswick to N.E. FloridaMostly in river mouths, estuaries and bays but also enters open seaSeriously depletedTo 1 m (40 in) in length

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3. GREEN STURGEON–ACIPENSER MEDIROSTRIS23-30 scutes in midside row1-2 mid-dorsal scutes behind dorsal fin4 barbels nearer mouth than snout tipGrayish white to olive-greenBottom grubbingOften in brackish waterJapan to Northern BajaTo 2.1 m (7 ft) in length and 159 kg (350 lbs)

4. WHITE STURGEON–ACIPENSER TRANSMONTANUS38-48 scutes in midside rowNo mid-dorsal scute after the dorsal fin4 barbels closer to snout tip than mouthGrayish whiteSpawns in spring in fresh waterImportant commercially for flesh and eggs (caviar)Mainly in fresh water; occasionally moves to oceanCommon in large riversAlaska to Northern BajaTo 3.1 m (10 ft) in length and 181 kg (400 lbs)

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THREATS Pollution and environmental degradation Over-fishing – for eggs/roe, meat and swim bladders

CONSERVATION The World Conservation Union considers all but two of the world’s sturgeon and paddlefish species globally threatened. Consumer demand for caviar and the collapse of Russian law enforcement in certain areas have caused a boom in illegal poaching. Habitat destruction has also contributed to the decline of these fish.

IUCN classifies the Great/Beluga sturgeon (Huso huso) as Endangered. It is a protected species and its trade is restricted under CITES. The U.S. Fish & Wildlife Service has also banned imports of beluga caviar and other beluga sturgeon products from the Caspian Sea since October 7, 2005.

The World Wildlife Fund suggests not buying Beluga, Ossetra or Sevruga caviar, or caviar from the Caspian Sea region, which includes Russia, Kazakhstan, Turkmenistan, Azerbaijan and Iran.

Sturgeon and/or paddlefish farming may become a viable means of sustainable commercial caviar production. It is currently practiced in Spain, France, Uruguay and the U.S. (California).

Dwindling sturgeon numbers has also resulted in the creation of caviar-quality roe alternatives from other fishes, such as Paddlefish, Whitefish, Cod, and Salmon.

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REFERENCES & FURTHER READING

http://www.caviaremptor.org/"Caviar Emptor" strives to protect critically endangered beluga sturgeon and other threatened Caspian Sea sturgeon species (source of most of the world's caviar).

http://www.fishbase.orgExcellent source of information about fishes

http://www.worldwildlife.org/trade/faqs_caviar.cfmWorld Wildlife Fund information on caviar trade

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6.3.3 Sea Otters

DESCRIPTIONLong, sleek, furred, streamlined marine mammalsLargest member of the weasel family; 1.2-1.5 m (4-5 ft) long and weigh 20-45 kg (45-100 lbs)Webbed hind feet; smaller front feet; ears and nostrils close when underwater.Dense, luxurious, dark-brown fur; only marine mammal with almost no insulating fat

SPECIESOne species, Enhydra lutris, and two sub-species:

Enhydra lutris nerisis – Southern/Californian sea otter Enhydra lutris lutris – Northern/Alaskan sea otter

SIZESouthern sea ottersFemales 1.2 m (4 ft) in length & 20 kg (45 lbs) in weightMales 1.5 m (5 ft) in length & 30 kg (65 lbs) in weight

Northern sea ottersGenerally heavier and more robust; Males up to 45 kg (100 lbs)

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FURTwo layers; soft, warm, dense undercoat and outer coat of guard hairsDensest fur of any mammal – 500,000-1,000,000 hairs per sq. inchGroom fur with forepaws to keep the fur waterproofAlmost no layer of insulating fatOil spills cause the fur to lose its waterproofing capability causing the sea otter to get hypothermia and usually killing it

“POUCH”Under each foreleg and extending across the chest is loose skin which can act as a “pouch”. Sea otter may carry up to 25 sea urchins and a number of clams or stones in this pouch depending on their size.

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SENSESKeen senses – smell, hearing and sightCan see very well, both above and below water

TEETHPowerful jaws for crushingCompact molars with smooth cusps; canines are rounded and suited for crushing shellfishLook “cute and cuddly” but they are large carnivores – they can and do bite!

LIFESPANMale: 10-15 years in the wildFemale: 15-20 years in the wild

GROOMINGMay spend 11%-48% of daylight hours groomingExtreme flexibility allows them to groom all parts of their body

DIVINGDive to about 100 m (330 ft)Sea otters can hold their breath for 5 minutesMost dives are about 1-1½ minutes long

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DIETCarnivores (meat eaters)Eat crustaceans (crabs, lobsters, shrimps), bi-valves (clams, mussels, abalone), sea-urchins and snailsAlso eat octopuses, squid, and fishHunt for prey in the ocean and on the sea floorUse rocks to help crack open clams and abalone

High metabolism – eat 20%-30% of their body weight a day in the wild. This would be equivalent to a 68 kg (150 lb) human eating 14-23 kg (30-50 lbs) of food a day just to survive

BEHAVIOUREither solitary or in groups called raftsFemales avoid males outside breeding periodsSea otters segregate into male and female areasDiurnal – hunt, feed and groom during the daySleep and rest on their backs, usually anchored in kelpWrap themselves in mats of kelp to secure them from currentsTool use – underneath each front arm is a pouch of skin used to temporarily store food and rocks collected during extended dives to the bottom. Floating on their backs, sea otters wash and hammer or pry open prey with a favored rock they keep in their pouch. Only mammal, besides primates, known to use tools.

406.3 OCEAN LIFE

BREEDING & REPRODUCTIONPolygynous – one male may mate with several femalesMales reach sexual maturity at 5-6 years oldFemales come into estrus at 4-6 years oldBirths occur all year but peak in Jan-Mar and Aug-OctFemales give birth to one pup after a gestation period of 6-8 monthsCourtship is often very playful. Males and females swim and dive together with the male twisting and doing corkscrews in the water. The male will also swim face down and much more quickly than usual.Females may also have scars on their nose from the males’ habit of holding the females muzzles in their jaws during copulation.May be a period of delayed implantation during which the fertilized egg lies dormant – allows birth to be timed to when food is more plentiful or conditions are better.

PREDATORSGenerally only a few

Ocean:Killer whales; some sharks (great white) & birds (bald eagle)

Land:Bears and coyotes

416.3 OCEAN LIFE

INTERESTING FACTSBones can be pale violet from eating purple sea urchins and absorbing a chemical called “polyhydronaphthoquinone” from the sea urchin.

Fifth digit (“pinkie”) on the hind foot is the longest digit, unlike that of any other mammal.

Uses a rock as an anvil and hammers shellfish onto the rock to smash it open. Rare example of mammalian tool use.

Smallest marine mammal

Does not have blubber

Has little/no need to come onto land – all life functions can and are usually taken care of in water (i.e. breeding, birthing, mating, eating, resting, grooming, etc).

Considered to be a keystone species controlling the population of several invertebrates, which would otherwise grow unchecked.

426.3 OCEAN LIFE

CLASSIFICATION

436.3 OCEAN LIFE

HABITATShallow coastal waters of northern Pacific Ocean.

RANGELive along rocky northern Pacific Ocean coasts, bays and kelp beds. Historic range throughout the northern Pacific Ocean from Baja, California through Washington, British Columbia, and Alaska to the Aleutian Chain, Kamchatka, eastern Russia and northern Japan. Much sparser distribution today due to over-hunting of sea otters for their pelts.

POPULATION2,500 southern sea otters off the coast of California

27,500-52,500 northern sea otters in Alaska, Canada and Washington.

15,000 in Russia

446.3 OCEAN LIFE

THE GREAT HUNTBetween the 17th and 19th centuries, Russia was heavily involved in the sable fur trade. Peter the Great declared that Russia should have the monopoly in sable furs and that they should find new populations of sable to hunt. The Russians conquered Kamchatka, at the eastern edge of Russia, where they harvested sable and sea otter fur, and explored the northwestern Pacific looking for sea routes to North America.Vitus Bering, a Dane in the service of the Russian navy, was given the task of mapping the Arctic coast from northern Russia to the Americas. Bering’s 1741 expedition to North America returned with 900 sea otter pelts – enough to pay for the entire expedition and set what came to be known as the Great Hunt in motion. Subsequently, the Russians sent many ships to hunt sea otters, which depleted their populations in the Commander and Aleutian Islands. By 1776, the Americans and Europeans were also hunting sea otters and competing with one another for domination of the fur trade. By 1867, Alaska was almost completely depleted of sea otters. It wasn't until 1911 that an international treaty was signed to stop the hunting of sea otters and the Great Hunt was finally over.By that time, however, so few sea otters remained, many assumed they would become extinct. Indeed, all California sea otters were thought to be extinct into the 1900’s. In 1915, however, 32 sea otters were discovered at Point Sur in California. So fragile was this remnant population that biologists kept it secret from the public until the 1930's. This and other surviving groups would form the nucleus for the restoration of the sea otters.Since then, and under strict protection, both Northern and Southern sea otter populations have grown considerably but in some areas, their numbers are still precariously low (hence the Southern sea otters’ “Threatened” status). Today, new challenges threaten the sea otter’s existence, including pollution and habitat destruction.

456.3 OCEAN LIFE

THREATS• Hunting – almost driven extinct in the past; protected today• Oil spills & pollution• Habitat loss• Disease and medical problems• Gill net entanglement• Human-sea otter competition – sea otters can damage valuable abalone & shellfish farms

CONSERVATIONCalifornia (Southern) sea otters listed as “threatened” under the federal Endangered Species Act (ESA) and are fully protected under California state law. Alaskan (Northern) sea otters are “endangered”. All otters in the USA are protected under the US Marine Mammal Protection Act (MMPA). Canadian otters are classed as “threatened” by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC).

Even though they are protected, some threats have no boundaries:• Exxon Valdez spill in Prince William Sound, Alaska (1989) killed several thousand sea otters• Sticky crude oil causes water-logging of the coat & the animal quickly chills in the cold water• May also succumb to the toxic components in the oil itself

REFERENCES & FURTHER READINGhttp://www.marinemammalcenter.org/learning/education/teacher_resources/cleanseaotter.asphttp://en.wikipedia.org/wiki/sea_otter - sea otter species information, habitat, behavior, threats

466.4 ACTIVITIES

6.4 ACTIVITIES

476.4 ACTIVITIES

6.4 ACTIVITIES

6.4.1 Horseshoe Crabs

CORE ACTIVITY

(a) Colour the horseshoe crab olive and add the following labels to your picture:

Top View Head (prosoma) Eyes Eyes (second set) Flange Hinge Abdomen (opisthosoma) Spines Tail (telson)

Bottom View Mouth Flange Feeding pincers (chelicerae) Tail (telson) Walking legs Book Gills Anus

486.4 ACTIVITIES

496.4 ACTIVITIES

(b) What are some differences between a horseshoe crab and true crab?

Horseshoe Crabs True Crabs

(c) What colour is horseshoe crab blood?

(d) If you have to pick up a horseshoe crab, where should you hold it?

506.4 ACTIVITIES

ANSWERS

(a) Colour the horseshoe crab olive and add the following labels to your picture:

Top View Head (prosoma) Eyes Eyes (second set) Flange Hinge Abdomen (opisthosoma) Spines Tail (telson)

Bottom View Mouth Flange Feeding pincers (chelicerae) Tail (telson) Walking legs Book Gills Anus

516.4 ACTIVITIES

526.4 ACTIVITIES

(b) What are some differences between a horseshoe crab and true crab?

(c) What colour is horseshoe crab blood?Light-blue, copper-based blood (unlike humans, which have red, iron-based blood)

(d) If you have to pick up a horseshoe crab, where should you hold it?From the flange at the front of the head as though you were holding a bicycle helmet – not by the tail as you can snap it off!

Horseshoe Crabs True Crabs

No antennae No mandibles Multiple un-stalked eyes Molt by walking forward out of their shell

Have antennae 1 pair of mandibles Stalked eyes True crabs back out of their shell when molting

12 legs (6 pairs) including 6 pairs of claws: 1st pair (chelicerae) – for feeding 2nd pair (pedipalps) – differentiate gender Remaining pairs are walking legs

10 legs (5 pairs) including 1 pair of claws

536.4 ACTIVITIES

6.4.2 Sturgeons

CORE ACTIVITY

(a) Colour the sturgeon dark grey and add the following labels to your picture:

Scutes (plated “scales”) Pectoral Fin Caudal Fin (“tail”) Barbels (“whiskers”) Snout Eye

(b) What is caviar?

(c) Why are sturgeons endangered?

(d) Why is the gathering of caviar from sturgeons so detrimental to the population?

546.4 ACTIVITIES

ANSWERS

(a) Colour the sturgeon dark grey and add the following labels to your picture:

Scutes (plated “scales”) Pectoral Fin Caudal Fin (“tail”) Barbels (“whiskers”) Snout Eye

556.4 ACTIVITIES

(b) What is caviar?“Caviar” refers to the processed, salted eggs/roe of certain species of fish, most notably the sturgeon. Sturgeon caviar or true caviar is sold worldwide as a delicacy, and is usually eaten by itself or spread on toast or blinis (small, yeast-raised Russian buckwheat pancakes). Sturgeon eggs are round and vary in size from very small to pea-sized. Their colour can be off-white, gold, light grey, charcoal grey, or black.

(c) Why are sturgeons endangered?

• Pollution and environmental degradation• Over-fishing – for eggs/roe, meat and swim bladders

(d) Why is the gathering of caviar from sturgeons so detrimental to the population?

There are at least three reasons:

1. Gathering caviar (eggs) removes the next generation of sturgeons.2. The female sturgeon is killed in the process of extracting the eggs. 3. Sturgeons take many years to reach maturity and reproductive age

566.4 ACTIVITIES

6.4.3 Sea Otters

CORE ACTIVITY

(a) Colour the Sea Otter dark brown and add the following labels to your picture:

• Eye• Forepaw• Skin/Fur• Nostril• Hindpaw• Ear• Tail

(b) Name some of the sea otters most unusual features

576.4 ACTIVITIES

586.4 ACTIVITIES

(c) Sea otters are found along the coast of the North Pacific ocean. Label the map with the following places:

• California (CA), USA• Alaska (AK), USA• Canada• Kamchatka Peninsula• Russia• China

596.4 ACTIVITIES

ANSWERS

(a) Colour the Sea Otter dark brown and add the following labels to your picture:

• Eye• Forepaw• Skin/Fur• Nostril• Hindpaw• Ear• Tail

(b) Name some of the sea otters most unusual features• Bones can be pale violet from eating purple sea urchins• Fifth digit (“pinkie”) on the hind foot is the longest digit, unlike that of any other mammal.• Uses rocks as an anvil and hammers shellfish onto the rock to smash it open• Smallest marine mammal• Does not have blubber• Densest fur of any mammal – 500,000-1,000,000 hairs per sq. inch

606.4 ACTIVITIES

616.4 ACTIVITIES

(c) Sea otters are found along the coast of the North Pacific ocean. Label the map with the following places:

• California (CA), USA• Alaska (AK), USA• Canada• Kamchatka Peninsula• Russia• China