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Sea Otters - marine mammals - Unknown.pptx
- 2. • B i o l o g y • E c o l o g y • C o n s e r v a t i o n Photo: Joe Tomoleoni ”More than furry and cute”
- 3. Taxonomy F a m i l y S u b - F a m i l y G e n u s Mustelids (Mustelidae e) Weasels Otters (Lutrinae) Badgers Martens Wolverines Giant otter Lontra (4 species) Sea otter (Enhydra) Spotted-necked otter (Hydrictis) Lutra (2 species) African clawless (Aonyx) Asian small-clawed S u b - s p e c i e s Asian sea otter (Enhydra lutris lutris) Northern sea otter (Enhydra lutris kenyoni) Southern sea otter (Enhydra lutris nereis)
- 4. Distribution & population • Within 1km from shore • Historic population: 150,000 – 300,000 • <1% left after hunting between 1740-1911 • Alaska: 73,000
- 5. Adaptations encompasses all mammals whose survival depends entirely or almost entirely on the oceans, which have also evolved several specialized aquatic traits. M a r i n e M a m m a l
- 6. Diet
- 9. Life Cycle
- 10. T he nose knows
- 11. Keystone Species
- 12. T hreats & Conser vation
- 13. THANK YOU
Editor's Notes
- “Learn about the ecosystem role of sea otters as keystone species, maintaining kelp forest health. Explore their remarkable behaviors, from ingenious tool use to intricate social interactions, while understanding the conservation challenges these adorable marine mammals.”
- “Learn about the ecosystem role of sea otters as keystone species, maintaining kelp forest health. Explore their remarkable behaviors, from ingenious tool use to intricate social interactions, while understanding the conservation challenges these adorable marine mammals.”
- Family: The Mustelidae (/mʌˈstɛlɪdiː/;[2] from Latin mustela, weasel) are a diverse family of carnivorous mammals, including weasels, badgers, otters, martens, and wolverines. Otherwise known as mustelids (/ˈmʌstɪlɪdz/[3]), they form the largest family in the suborder Caniformia of the order Carnivora with about 66 to 70 species in nine subfamilies.[4] Sub-Family: Otters are carnivorous mammals in the subfamily Lutrinae. The 13 extant otter species are all semiaquatic, aquatic, or marine, with diets based on fish and invertebrates. Enhydra is a genus of mustelid that contains the sea otter and two extinct relatives. It is the only extant genus of the bunodont otters group, referring to otters with non-blade carnassials with rounded cusps.[1] Sea otters probably diverged from other otters during the Pliocene, approximately 5 mya.[2] They probably arose from the closely related Enhydritherium, a bunodont otter endemic to North America during the late Miocene and early Pliocene epochs.[1] Enhydra reevei, the oldest known species, has its origins in the Atlantic, suggesting this may have been where sea otters originated.[2] Fossil evidence indicates the Enhydra lineage became isolated in the North Pacific approximately 2 million years ago, giving rise to the now-extinct Enhydra macrodonta and the modern sea otter. Other genus: Lontra, 4 species of otters of the Americas. Lutra: European river otter Three subspecies of the sea otter are recognized with distinct geographical distributions. Enhydra lutris lutris (nominate), the Asian sea otter, ranges across Russia's Kuril Islands northeast of Japan, and the Commander Islands in the northwestern Pacific Ocean. In the eastern Pacific Ocean, E. l. kenyoni, the northern sea otter, is found from Alaska's Aleutian Islands to Oregon and E. l. nereis, the southern sea otter, is native to central and southern California.[22] The Asian sea otter is the largest subspecies and has a slightly wider skull and shorter nasal bones than both other subspecies. Northern sea otters possess longer mandibles (lower jaws) while southern sea otters have longer rostrums and smaller teeth.
- - three subspecies in different areas. Where we are sailing we will find the Northern Sea Otter. - live in coastal waters 15 to 23 metres (49 to 75 ft) deep, and usually stay within 1km of the shore. Individuals generally occupy a home range a few kilometres long, and remain there year-round. - They are found most often in areas with protection from the most severe ocean winds, such as rocky coastlines, thick kelp forests, and barrier reefs. Although they are most strongly associated with rocky substrates, sea otters can also live in areas where the sea floor consists primarily of mud, sand, or silt. Their northern range is limited by ice, as sea otters can survive amidst drift ice but not land-fast ice. - Their current distribution is fragmented, this is due to excessive hunting. Sea otters, whose numbers were once estimated at 150,000–300,000, were hunted extensively for their fur that started in 1741. “captain james cook first sailed into these waters in 1778. He left with otter pelts, which he sold for a huge profit in China. It wasn’t long before Russian fur traders also came looking for otter pelts, which they called soft gold. By 1910, less than a 1,000 sea otters were left from an original population over a quarter of a million. In Canada they were completely wiped out” By 1911, the world population fell to 1,000–2,000individuals living in a fraction of their historic range. The commercial harvest continued until sea otters gained protection in 1911 at the signing of a fur seal treaty between Russia, the US, Britain and Japan. Records for the total harvest are scarce, but fur traders likely killed close to a million sea otters during a century-and-a-half of exploitation in Alaska. - Population estimates made between 2004 and 2007 give a worldwide total of approximately 107,000 sea otters. Alaska Alaska is the central area of the sea otter's range. In 1973, the population in Alaska was estimated at between 100,000 and 125,000 animals.[111] By 2006, though, the Alaska population had fallen to an estimated 73,000 animals.[103] A massive decline in sea otter populations in the Aleutian Islands accounts for most of the change; the cause of this decline is not known, although orca predation is suspected.[112] The sea otter population in Prince William Sound was also hit hard by the Exxon Valdez oil spill, which killed thousands of sea otters in 1989. British Columbia Along the North American coast south of Alaska, the sea otter's range is discontinuous. A remnant population survived off Vancouver Island into the 20th century, but it died out despite the 1911international protection treaty. From 1969 to1972, 89 sea otters were flown or shipped from Alaska to the west coast of Vancouver Island. This population increased to over 5,600 in 2013. In 1989, a separate colony was discovered in the central British Columbia coast. It is not known if this colony, which numbered about 300 animals in 2004, was founded by transplanted otters or was a remnant population that had gone undetected. By 2013, this population exceeded 1,100individuals, was increasing at an estimated 12.6% annual rate,
- The sea otter displays numerous adaptations to its marine environment. The nostrils and small ears can close. The hind feet, which provide most of its propulsion in swimming, are long, broadly flattened, and fully webbed. The fifth digit on each hind foot is longest, facilitating swimming while on its back, but making walking difficult. The tail is fairly short, thick, slightly flattened, and muscular. The front paws are short with retractable claws, with tough pads on the palms that enable gripping slippery prey. The bones show osteosclerosis, increasing their density to reduce buoyancy. The sea otter propels itself underwater by moving the rear end of its body, including its tail and hind feet, up and down, and is capable of speeds of up to 9 kilometres per hour. When underwater, its body is long and streamlined, with the short forelimbs pressed closely against the chest Unlike most other marine mammals, the sea otter has no blubber and relies on its exceptionally thick fur to keep warm. With up to 150,000 strands of hair per square centimetre (970,000/in2), its fur is the densest of any animal. (in comparison, a human head has about 100,000 hairs??!?) The fur consists of long, waterproof guard hairs and short underfur; the guard hairs keep the dense underfur layer dry. There is an air compartment between the thick fur and the skin where air is trapped and heated by the body. Cold water is kept completely away from the skin and heat loss is limited. Sea otters spend much of their time grooming, which consists of cleaning the fur, untangling knots, removing loose fur, rubbing the fur to squeeze out water and introduce air, and blowing air into the fur (you might see them barrelrolling to do this). To casual observers, it appears as if the animals are scratching, but they are not known to have lice or other parasites in the fur. Having only returned to the sea about 3 million years ago, sea otters represent a snapshot at the earliest point of the transition from fur to blubber. In sea otters, fur is still advantageous, given their small nature and division of lifetime between the aquatic and terrestrial environments. However, as sea otters evolve and adapt to spending more and more of their lifetimes in the sea, the convergent evolution of blubber suggests that the reliance on fur for insulation would be replaced by a dependency on blubber. This is particularly true due to the diving nature of the sea otter; as dives become lengthier and deeper, the air layer's ability to retain heat or buoyancy decreases, while blubber remains efficient at both of those functions. Blubber can also additionally serve as an energy source for deep dives, which would most likely prove advantageous over fur in the evolutionary future of sea otters.
- But living in this cold water as a relatively ‘new’ marine mammal comes at a cost; sea otters have a metabolic rate two or three times that of comparatively sized terrestrial mammals. It is estimated they have to eat 25-38% of their own body weight in food each day to stay warm. And when you need to eat that much, you can’t be too picky. Sea otters feed on about 100 different species of mostly benthic invertebrates, including sea urchins, clams, mussels, scallops, worms, abalone, limpets, snails, and crustaceans. In some cases they might also eat fish, for example when their population is at carrying capacity and there might not be enough of the other stuff. Contrary to popular depictions, sea otters rarely eat starfish, and any kelp that is consumed apparently passes through the sea otter's system undigested. When pups learn the hunt, however, they often come of with bright-coloured starfish and pebbles, but they soon learn that this has little to no nutritional value. Most of its need for water is met through food, although, in contrast to most other marine mammals, it also drinks seawater. Its relatively large kidneys enable it to derive fresh water from sea water and excrete concentrated urine.
- - The sea otter is diurnal. It has a period of foraging and eating in the morning, starting about an hour before sunrise, then rests or sleeps in mid-day. Foraging resumes for a few hours in the afternoon and subsides before sunset, and a third foraging period may occur around midnight. - The sea otter hunts in short dives, often to the sea floor. Although they can hold their breath up to 5 minutes, dives are usually around 1 minute. - Being a relatively ‘new’ marine mammal doesn’t just come with the disadvantage of being cold and needing to eat a lot, but it also comes with the advantage of still having usable ‘hands’. Sea otters are the only marine animals that are capable of lifting and turning over rocks, which it often does with its front paws when searching for prey. When hunting for fish, it is the only marine mammal that catches fish with its forepaws rather than with its teeth. Fun Fact: One researcher spent days and days observing sea otter feeding behaviour. He observed hundreds of animals, and not once seen food items brought to the surface under the right forelimb, unless the quantity was too great for the left limb to accommodate. He therefore concluded that sea otters are right-handed! - And there’s something even more special about them: They are one of the few mammal species to use tools! To open hard shells, it may pound its prey with both paws against a rock on its chest. To pry an abalone off its rock, it hammers the abalone shell using a large stone, with observed rates of 45 blows in 15 seconds. Releasing an abalone, which can cling to rock with a force equal to 4,000 times its own body weight, requires multiple dives. - Under their forelimb they have a loose skin flap that forms a ‘pouch’ in which they can keep food, but also their favourite rock. - Favourite rock: Haley, D., ed. (1986). "Sea Otter". Marine Mammals of Eastern North Pacific and Arctic Waters(2nd ed.). Seattle, Washington: Pacific Search Press. ISBN 978-0-931397-14-1.OCLC 13760343 . (https://www.worldcat.org/oclc/13760343)
- Although sea otters can be playful and sociable, they are not considered to be truly social animals They spend much time alone, and each adult can meet its own hunting, grooming, and defense needs. Although each adult and independent juvenile forages alone, sea otters tend to rest together in single-sex groups called rafts. A raft typically contains 10 to 100 animals, with male rafts being larger than female ones. The largest raft ever seen contained over 2000 sea otters. To keep from drifting out to sea when resting and eating, sea otters may wrap themselves inkelp. The species exhibits a variety of vocal behaviors. The cry of a pup is often compared to that of a gull. Females coo when they are apparently content; males may grunt instead. Distressed or frightened adults may whistle, hiss, or in extreme circumstances, scream.
- Females become sexually mature at around three or four years of age and males at around five; however, males often do not successfully breed until a few years later (males have to fight for territory, young males usually lose this). Males have multiple female partners, typically those that inhabit their territory. When a male sea otter finds a receptive female, the two engage in playful and sometimes aggressive behavior. They bond for the duration of estrus, or 3 days. The male holds the female's head or nose with his jaws during copulation. Visible scars are often present on females from this behavior. Females are pregnant for 4 months, but gestation can sometimes last up to 12 months, as this species is capable of delayed implantation (as most seals). Births occur year-round, with peaks between May and June in northern populations. Birth takes place in the water, and typically only one pup is born. Twins happen in 2% of the births, but usually only one pup survives. Pups are born with their eyes open, already 10 teeth visible, and a thick coat of baby fur. They are nursed 4-12 months, and the mother produces a very fatty milk that resembles more the milk of marine mammals than of other mustelids. Pups stay at the surface while their mother dives for food. If it’s not sleeping, it will be crying. Females perform all tasks of feeding and raising offspring, and have occasionally been observed caring for orphaned pups. A mother gives her infant almost constant attention, cradling it on her chest away from the cold water and attentively grooming its fur. Mothers have been observed to lick and fluff a newborn for hours; after grooming, thepup's fur retains so much air, the pup floats like a cork and cannot dive. The fluffy baby fur is replaced by adult fur after about 13 weeks. Despite the mother’s impressive efforts, pup mortality is high,– by one estimate, only 25% of pups survive their first year. Mothers have been known to carry their pups for days after the pups' deaths.
- Photo ID of nose
- Sea otters, it turns out, are a classic example of how predators exert a strong top-down influence on an ecosystem.
- Conflict: Bad reputation because of competition. «raccoon of the sea». After 100 yeras absence people got used to harvesting urchins, clams and abalone, for which there is now a commercial demand. Although sea otters are protected, reports of people driving boats full-speed through sea otter rafts. West coast of Vancouver Island is remote and not monitored.