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Commonly Asked Questions

Appears in Georgia Aquarium's:
  • Sea Otters Habitat (Cold Water Quest)

Range / Habitat

  • Range:
    • Sea otter is found along coastal areas of the northern Pacific Ocean and the southern Bering Sea. Three separate sub species live along the coasts of Russia, Alaska, and California. Reintroduced populations in British Columbia and Washington state.
  • Distribution:
    • The southern subspecies lives along the central California coast from San Mateo County to Santa Barbara County. Historically, the range extended from Punta Abra Ojos, Baja California north to Prince William Sound Alaska.
  • Habitat:
    • Found in marine habitats with rocky or muddy sea bottoms and is frequently associated with kelp forests. Rarely ventures onto land.

Physical Characteristics

  • Size:
    • Adult southern sea otters are approximately 4 feet (1.2 m) in length. Adult males average 65 lbs. (29.5 kg) and adult females average 45 lbs. (20 kg) in weight.
    • A newborn southern sea otter pup is a buff color, 22 to 24 inches (55 - 60 cm) in length and 4 to 5 lbs. (1.8-2.3 kg).
  • Color:
    • The southern sea otter is dark to reddish brown in color with a lighter colored head, throat, and chest.
  • Body Composition:
    • It has a long, stout body with a short broad head and snout with thick whiskers on the cheeks.
    • The tail is short in comparison to those of other otters.
    • Webbed hind feet that can be spread wide like flippers are well adapted for swimming.
    • Forepaws are smaller with retractable claws and are used to groom, eat, and hold tools for breaking open prey.
    • Classified as a marine “fissiped”, the sea otter is an aquatic carnivore that is well-adapted for its life at sea. The digits on its front paws are separated and covered, similar to mittens. Its claws are retractable and the front paws have rough pads. These features help sea otters more easily grasp their slippery or spiny prey. On the hind paws, the pads are reduced and may be absent, except on the toes. The fifth digit or little toe is longer than all other otters, allowing the sea otter to spread its webbing wider when swimming.
  • Teeth:
    • The majority of the southern sea otter’s teeth are flattened molars for crushing and chewing shelled, invertebrate prey. The otter has a set of canine teeth as well.
    • Major tooth wear is a cause of mortality in older otters.
  • Fur:
    • Sea otter’s body is covered in a dense fur that constantly must be groomed to maintain its insulating properties and cleanliness; therefore, a sea otter will spend up to 10% of its time grooming.
    • This thick coat helps to maintain its body temperature in the cold ocean water.
    • The fur of the sea otter is the densest of all mammals at about 350,000 to 1,000,000 hairs per square inch, compared to dogs that only have 1,000 to 60,000 hairs per square inch.
    • The sea otter’s fur also is designed to trap air to further insulate it from the cold water and to provide additional buoyancy.

Diet / Feeding

  • Diet/Amount:
    • Southern sea otter consumes many types of prey including sea urchins, snails, clams, abalone, mussels, crabs, scallops, fish, barnacles, octopus, worms, and squid, which it captures with its clawed paws, not its jaws.
    • It must eat 20 to 25 percent of its body weight every day to maintain normal body temperature, so it will spend much of the day foraging.
    • This species, considered a keystone species, helps maintain the health of kelp forests by preying on sea urchins, which, if allowed to proliferate, can destroy a kelp forest. The urchin feeds on the holdfast or base of young kelp, which can set it adrift. An adult male sea otter may eat as many as 50 urchins each day.
  • Feeding behaviors:
    • It uses rocks, shells and other hard materials from the ocean floor as shell-crushing tools, while balancing its prey on its chest and stomach.
    • Studies on southern sea otters in California have shown that diet can be a highly individual thing, in which an otter will specialize in one to three types of prey that is not influenced directly by prey availability. However, most individuals will take advantage of seasonally abundant swells in prey species, such as squid and red crab.
    • Uses its nose and whiskers to help locate prey and to detect vibrations under the water. It also uses a flap of skin located under each foreleg to hold food temporarily while hunting until it returns to the surface.

Reproduction / Growth

  • Females give live birth to,normally, one pup at a time.
  • Pups remain dependent upon their mothers for approximately six months.

Conservation Status

  • Conservation Status:
    • Sea otters (Enhydra lutris) are “Endangered” on the IUCN Red List.
    • Enhydra lutris nereis is listed on Appendix I of CITES. The other subspecies of sea otter are Appendix II.
    • Listed as “threatened” under the U.S. Endangered Species Act and “depleted” under the U.S. Marine Mammal Protection Act of 1977.
  • Threats:
    • Potential current threats to this protected subspecies include entanglement in fishing nets, oil spills and predation by the great white shark.
    • Once common along most of the coastal North Pacific Ocean from Japan to California, in the nineteenth and early twentieth centuries, it was hunted to the verge of extinction for its prized pelt.

Additional Information

  • Lifespan:
    • The male lives to about 10 to 15 years in the ocean, while the female’s lifespan can be a little longer. Their lives are usually longer in an aquarium or zoo setting.
  • Reproduction:
    • During the mating season, the male bites the snout of the female in a display of courting behavior.  Consequently, sexually mature females can be distinguished by bloody or scarred nose regions.
    • Female sea otter is pregnant for four-and-a-half months.
    • Delayed implantation periods in sea otters depend on individual and geographic variation. It ranges from 2-3 months in southern sea otters and can last as long as 8 months in northern sea otters.
    • Sea otter pup can emit a strong high-pitched call when in distress or separated from its mother.  It is nursed by its mother for 6 months to a year, but can begin foraging in shallow water habitats as soon as 6 weeks after birth.
  • Social Behavior:
    • It is believed that a sea otter will wrap itself with kelp before sleeping at the surface to keep itself from drifting away.
    • Southern sea otter is not a social animal as are other otter species and has been known to live alone. However, it frequently occurs in small groups where food sources are plentiful and will rest in a group called a “raft”.
      • Males usually raft together during non-breeding season.
      • Adult males are highly territorial during breeding season and will not permit other males to enter their territory. 
      • Females raft with their pups and other females.
    • Although the pup ratio is about 50:50 males to females, there is a higher mortality rate among male pups. This results in a higher female to male ratio in adults.
  • Diving:
    • This otter can dive to 300 feet in search of food.
    • Southern sea otter usually submerge for about 52 to 90 seconds, but the longest dive recorded was 4 minutes and 25 seconds long.
  • Metabolism:
    • Southern sea otter has a high metabolic rate that is about 2.5 times greater than that of terrestrial animals. The hind feet and front paws lose the most heat because fur is sparse or absent, so the sea otter often can be seen holding them out of water to conserve body heat while it floats on its back at the surface.
  • Senses:
    • Hearing, smell, touch and sight are very well developed in the sea otter and are important in hunting as well as in detecting danger.
  • Family:
    • Southern sea otter belongs to family Mustelidae, the same as weasels and wolverines. 
  •    Our Southern Sea Otter Habitat:
    • Three interconnected spaces
    • Total water volume: ~24,800 gallons
    • Water Temperature: 56°F

Sources

www.iucnredlist.org
www.cites.org

National Audubon Society Guide to Marine Mammals of the World.  Reeves, R. R., et al.
Marine Mammals of the World.  Nowak, R. M.
National History of Otters. Chanin, P.
Marine Mammal Encyclopedia, Otters. Estes, James A. and Bodkin, James L.
Monterey Bay Aquarium