otter, name for a number of aquatic, carnivorous mammals of the weasel family, found on all continents except Australia. The common river otters of Eurasia and the Americas are species of the genus Lutra. The North American river otter, L. canadensis, ranges from N Alaska and Canada to the S United States. Its slender body is 21⁄2 to 3 ft (76–91 cm) long, excluding the 12-in. (30-cm), heavy tail; it weighs from 10 to 25 lb (4–10 kg). It has thick, glossy brown fur, which is commercially valuable. The head is flattened, the legs are short, and the hind feet are webbed. An agile swimmer, it fishes in streams and lakes, along the banks of which it makes its burrow. It also eats frogs, crayfish, and other water animals. Although it spends most of its time in water, it makes overland trips on occasion. The otter is a social and playful animal; groups have been seen playing “follow the leader,” sliding down mudbanks, or tobogganing in the snow, apparently for the sake of pleasure. Of the freshwater otters, the South American giant otter, Pteronura brasiliensis, is the most highly modified for aquatic life. Its highly streamlined body is up to 7 ft (213 cm) long, the tail is keeled, and the feet are short, webbed, and nearly useless on land. Its mouth is set under the muzzle, like that of a shark. Hunted extensively for its fur, the giant otter may be in danger of extinction over much of its range. Otters of other genera are found in Africa and SE Asia. The sea otter, Enhydra lutris, found in and around the kelp beds of the N Pacific, is the only exclusively marine species, although river otters sometimes enter the ocean at the mouths of rivers. The sea otter swims on its back and in this position carries its cub and eats its meals of abalone, crab, and sea urchin, sometimes using a rock to smash open the shells. Relentless hunting of the animal led to its near extinction; however, it is now protected by international agreement. Otters are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Carnivora, family Mustelidae.
See E. Park, The World of the Otter (1972); P. Chanin, The Natural History of Otters (1985).
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