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Walrus: Odobenus rosmarus
Distribution: Arctic seas from Alaska, Canada and Greenland to the USSR.
Habitat: open water, near to shore or on ice floes.
Size: Height: up to 150cm. Length: bulls, 300-370cm. Weight: 900-1600kg.
Life-span: up to 50 years
Sexual Maturity: females: 6-7 years, males: 15 years.
Food: mainly molluscs and other invertebrate marine animals. Sometimes fish and seals.
Description: long tusks, bristly moustache and deeply wrinkled brown skin.
Gestation: 18-24 months
Number of young: 1
Walruses have very thick skin and underneath this, a layer of blubber which can be up to 15cm thick. They need this kind of protection from the sub-zero temperatures of the Arctic seas in which they live.
Sometimes walruses 'haul out', either onto rocky shores or ice floes. Quite often, they use their tusks like ice axes to help them get a better grip as they climb out of the water. The tusks are modified canine teeth which grow throughout the walrus' life. Tusks can be up to 60cm long in females, and up to 1m long in males! The longest walrus tusk ever recorded was 94cm long, 27cm in diameter and weighed over 5kg. The tusks are also status symbols, and the larger the tusks, the more important the owner of them will be in a herd.
On land walruses are clumsy. Their feet have been flattened into flippers and, when on land, they turn their back limbs forward so that they can lumber along on all fours. The bottoms of their flippers are warty to allow them to grip ice better. In water, the hind limbs act as the walrus' propellers, while the forelimbs are used as rudders.
In the Arctic winter, walruses head south. Unlike seals, they are unable to survive under pack ice because they cannot make holes in the ice to breathe through. When spring comes, the cows and immature animals head back north, but adult males linger in the south for longer.
Food and Feeding
Clams, cockles and mussels are the walrus main food. It uses the bristles of its moustache to sense its prey in the murky waters just above the sea bed. It possibly also uncovers food in soft mud by squirting water from its mouth.
Walruses will eat other marine invertebrates such as shrimps, worms, octopuses, sea cucumbers and some fish. They will even attack seals, grasping them with their forelimbs and slashing at them with their tusks.
Breeding. Breeding takes place between January and March. Large herds of bulls, cows and calves gather together and the bulls fight for the cows. Those with the longest tusks are those who get to mate with the cows, and each victorious male will mate with several.
Mating takes place in the water, and a single calf is born about 15 months after mating, often as the herds are heading back north after the winter. The female hauls out onto an ice floe to give birth to her calf, which measures 125cm at birth. The calf first travels by hanging onto its mother's neck, but it is quickly taught to swim and is quite a capable swimmer by two weeks of age. The calf feeds on its mother's rich milk for at least 18 months, but begins to eat solid food after six months and after a year will usually have tripled in weight. The calf separates from its mother after about two years, and attaches itself to a herd of young walruses.
Walruses and humans
Threats to the walrus. Over exploitation by hunters has made walruses endangered throughout their range, although numbers have recovered in the north Pacific. Most of the damage was done in the last three centuries by commercial hunters, who made them nearly extinct in the north Atlantic.
Today, numbers in the Bering Sea stand at around 250,000, but the walrus is still considered threatened as it breeds slowly and lives in a fragile habitat sensitive to pollution or overfishing.
Eskimos are still allowed to hunt walruses, as they have done for many hundreds of years. Walrus skins are used to make oil. The tusks are also used to make ornaments. As Eskimos now use high-powered rifles rather than traditional fishing lines to hunt walruses, their potential catch has been greatly increased.