sea otter, aquarium

The sea otter (Enhydra lutris) is a marine mammal native to the coasts of the North Pacific, from northern Japan, the Kuril Islands and Kamchatka east across the Aleutian Islands and along the North American coast to Mexico.

Adult sea otters typically weigh between 14 and 45 kg (30 to 99 lb), making them the heaviest members of the weasel family, but among the smallest marine mammals. Unlike most marine mammals, the sea otter's primary form of insulation is an exceptionally thick coat of fur, the densest in the animal kingdom with up to 400,000 hairs per cm2 (2.5 million per in2). It inhabits nearshore environments where it can quickly dive to the sea floor to forage. Although sea otters can walk on land, they are capable of spending their entire lives in the ocean.

The sea otter preys mostly upon marine invertebrates such as sea urchins, diverse mollusks and crustaceans, and some species of fish. Its foraging and eating habits are noteworthy in several respects: Its use of rocks to dislodge prey and to open shells makes it one of the few mammal species to use tools. In most of its range, it is a keystone species, controlling sea urchin populations which would otherwise inflict extensive damage to kelp forest ecosystems. Kelp forests provide crucial food and habitat for a variety of marine organisms, and help contain coastal erosion. Finally, its diet includes prey species that are also valued by humans as seafood, and this has led to conflicts with fisheries.