The Atlantic subspecies O.r.rosmarus measures about 300 cm and weigh 1'200 kg. Females measure 250 cm and weigh 750 kg. The Pacific walrus O.r.divergens is slightly larger.
Walruses use their whiskers (vibrissae) to locate food. A walrus has about 400-700 vibrissae on its snout, which are attached to muscles, and are supplied with blood and nerves. A walrus moves its snout through bottom sediment to find food.
Seasonal dynamics of sea ice cover in the Chukchi and Bering seas allow walruses to exploit a wide area of the continental shelf during the year. Adult male walruses have dorsal inflatable pharyngeal pouches, which allow them to sleep at the surface in open water for extended periods (Fay 1960) between foraging trips from land in summer (e.g. Jay et al. 2001).
Walruses are very gregarious and occur in groups of up to ~500 walruses (Fay 1985; Speckman et al. 2010). Group sizes of hauled out walruses tend to be larger when they are on shore than on ice (Fay 1985).
Walruses do not use their tusks to dig for food as is commonly believed. Rather, they use them for fighting and displays of dominance with other walruses, for defense against predators, as picks to pull themselves out of the water onto ice floes, and to kill and tear apart seals.
Walruses are subdivided into two subspecies: the Atlantic walrus (O. r. rosmarus) and the Pacific walrus (O. r. divergens). The Pacific walrus is distributed along the continental shelf of the Bering and Chukchi Seas.
Morphologically, the walrus is more similar to the Phocidae (true seals). Behaviorally, they more closely resemble the Otariidae (eared seals). Several studies based on molecular data have linked the walrus more closely to the otariids, yet the pinniped family that the odobenids are most closely allied to is still in question.
The common name, walrus, originated with the Danish word hvalros, meaning "sea horse" or "sea cow". The Russian word for walrus is morzh. Arctic natives call the walrus aivik (Inuit) or aivuk (Yu'pik).
The tusks ivory has been throughout human history one of the main reason for the hunting of walruses. In all part of their range walruses have been subject to commercial exploitation during the past 350 years and most populations have yet to recover.
The walrus, Odobenus rosmarus was named by Linnaeus in 1758. The name "Odobenus" in latin means "the one that walks on the teeth" while "rosmarus" is derived from old Norse and means "horse of the sea". It is the biggest seal species to inhabit the shallow waters of the Arctic Ocean.