walrus, marine mammal, Odobenus rosmarus, found in Arctic seas. Largest of the fin-footed mammals, or pinnipeds (see seal), the walrus is also distinguished by its long tusks and by cheek pads bearing quill-like bristles. Adult males are 10 ft (3 m) long or more, and weigh up to 3,000 lb (1,400 kg); females weigh about two thirds as much as males. The tusks, which are elongated upper canine teeth, may reach a length of 3 ft (90 cm) in large males and weigh over 10 lb (4.5 kg). The hide is very thick and wrinkled, and is light brown and nearly hairless. Beneath the hide is a layer of fat several inches thick. Like sea lions, walruses can turn their hind flippers forward for walking on land; their foreflippers are weaker than those of sea lions and they are not as strong swimmers. They live in shallow water and spend much of the time on ice floes and beaches, where they congregate in herds of about 100 animals of both sexes. They can dive to a depth of 240 ft (70 m) to find food, relying primarily on touch; their diet consists chiefly of shellfish, especially mollusks. The cheek teeth are rounded and are used for crushing shells. Walruses use their tusks for prying shellfish from the ocean floor, as well as for pulling themselves up onto ice floes. The herds tend to follow the ice line, moving south in winter and north in summer. Walruses have been very important in the economy of the Eskimo, who hunt them for food and clothing; the introduction of firearms greatly increased the size of the kill. Commercial hunting of walruses for blubber, hides, and ivory has been extensive since the 16th cent. and has greatly reduced the walrus population. Several nations now have protective laws; Canada and Russia prohibit walrus hunting except by peoples for whom it is a traditional part of the economy. There are two walrus races, the Atlantic and the Pacific. The Atlantic race, formerly found as far S as Nova Scotia and occasionally Massachusetts, is now considered endangered. The walrus's nearest living relatives are the fur seals, with which it evolved from bearlike ancestors, the Enaliarctidae, in the N Pacific Ocean about 20 million years ago. Walruses are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Carnivora, suborder Pinnipedia, family Odobenidae.
See R. Perry, The World of the Walrus (1968).