The walrus is a large flippered marine mammal with a discontinuous circumpolar distribution in the Arctic Ocean and sub-Arctic seas of the Northern Hemisphere. The walrus is the only living species in the Odobenidae family and Odobenus genus. It is subdivided into three subspecies: the Atlantic Walrus which lives in the Atlantic Ocean, the Pacific Walrus which lives in the Pacific Ocean, and O. rosmarus laptevi, which lives in the Laptev Sea.
The walrus is immediately recognized by its prominent tusks, whiskers and great bulk. Adult Pacific males can weigh up to 2,000 kilograms (4,400 lb) and, among pinnipeds, are exceeded in size only by the two species of elephant seals. It resides primarily in shallow oceanic shelf habitat, spending a significant proportion of its life on sea ice in pursuit of its preferred diet of benthic bivalve mollusks. It is a relatively long-lived, social animal and is considered a keystone species in Arctic marine ecosystems.