Sea otter

Scientific Name:
Enhydra lutris
1.3 m
26 kg
Clams, crabs, snails, starfish, abalone, and approximately 40 other marine animals.

Physical characteristics

Fur is brown or reddish brown; hind legs are long and the paws are broad, flat, and webbed; forelimbs are short and have retractable claws; Only have 4 lower incisors; Females have two mammae.

Behavioral characterization

Social, and tend to congregate in groups of gender, with pups and females in a group and males in another group. Females tend to stay away from males except when mating.


Found in coastal waters in the central and north Pacific Ocean. Past distribution of the sea otter included Hokkaido Island of Japan north through the Kuril Islands and eastern coast of Kamchatka, east through the Commander Islands and Aleutian archipelago, the southern coast of Alaska, and the west coast of North America to Baja, Mexico. Sea ice limits their northern range to below 57°N latitude, and the distribution of kelp forests limits the southern range to about 22°N latitude.

Population size

Population estimates made between 2004 and 2007 give a worldwide total of approximately 107,000 sea otters.


Killer whales and sea lions. Bald eagles also prey on pups by snatching them from the water surface.

Migration/Dispersal patterns

Russia, Alaska, British Columbia and Washington, California, and Oregon.

Social system/Group size


Major threats

Oil spills can be fatal to the sea otter. Oil coats the fur, destroying the blanket of air that keeps the animal warm. This causes chilling and death. Increased pollution in our oceans is also a threat to sea otters. Fishing nets are another cause of sea otter deaths. Sea otters become caught in the nets and drown. Laws have been passed to limit the use of fishing nets along the coastline. This has helped some sea otter populations.

Research efforts

Monterey Bay Aquarium Rescue and Rehabilitation.

Fun fact

Sea otter fur is the densest of all mammals with 100,000-400,000 hairs per square cm (that's up to one million hairs per square inch!) whereas humans only have 20,000 hairs on their whole head!