Walruses are huge Arctic pinnipeds, easily recognised by their tusks and bristly moustaches. Adult males are 2.7-3.6 meters (9-12 feet) long and weigh 800-1,700 kg (1,800-3,700 lbs), with Pacific walruses the largest. Females are about two-thirds that size.
Both sexes grow tusks, which are long upper canine teeth; in big males they can reach a meter (3 feet). Walruses use them to haul out onto ice, to break breathing holes, and to fight and show off. The face carries 400-700 stiff, sensitive whiskers that feel for food on the dark seabed.
Their skin is up to 10 cm (4 inches) thick over a blubber layer that keeps them warm. It looks pale in cold water and flushes pink or cinnamon brown when a walrus warms up on land. Walruses live around 40 years.
Walruses live in the shallow seas of the Arctic, where the water is rarely more than 80 meters (260 feet) deep and the seabed is rich in shellfish. Pacific walruses live in the Bering and Chukchi Seas between Alaska and Russia; Atlantic walruses range across the Canadian Arctic, Greenland, Svalbard and northern Russia.
They spend much of their lives on floating sea ice, which serves as a resting platform between feeding dives, and they come ashore on rocky beaches when the ice retreats in summer.
Walruses feed on the seabed, mainly on clams, which they find by feeling with their whiskers and dig out with jets of water. A walrus holds a clam in its lips and sucks the soft body out with a powerful piston-like tongue, swallowing thousands in a single feeding session.
They also eat snails, worms, crabs, shrimp and sea cucumbers, and a few large males hunt seals. Dives usually last 5-10 minutes.
Walruses are among the most social of all marine mammals. They haul out in tightly packed herds of hundreds or thousands, lying on top of one another to stay warm. Females and calves form their own herds, while males gather separately outside the breeding season.
Males court females with bell-like sounds made by air sacs in their throats. Mothers are devoted, carrying young calves on their backs and defending them fiercely. On land walruses are clumsy, but in water they are graceful swimmers.
The walrus, Odobenus rosmarus, is the only living member of the family Odobenidae. Its name comes from Greek words meaning "tooth-walking sea horse". There are two recognised subspecies, the Atlantic and Pacific walrus, and some scientists treat the walruses of Russia's Laptev Sea as a third.
The IUCN lists the walrus as Vulnerable, with a total population of roughly 225,000. Commercial hunting in the 18th and 19th centuries wiped out many herds, and today's biggest threat is the loss of summer sea ice. Without ice to rest on near their feeding grounds, tens of thousands crowd onto beaches, where stampedes can crush calves.
Shipping, oil and gas development and disturbance also affect them. Indigenous communities in Alaska, Canada, Greenland and Russia hunt walruses for food under regulated quotas.
