Walruses are large semi-aquatic mammals that live in the cold Arctic seas of the Northern Hemisphere. Two subspecies exist: the Atlantic, Odobenus rosmarus rosmarus, and the Pacific, Odobenus rosmarus divergens. more...
The Pacific walrus is slightly larger, the male weighing up to 4000 lb (1.8 t).
Walruses are members of order Pinnipedia and are the only members in the family Odobenidae. The compound Odobenus comes from odous (Greek for "tooth") and baino (Greek for "walk"), based on observations of walruses using their tusks to pull themselves out of the water. Rosmarus originates in the Swedish word for walrus. Divergens in Latin means "turning apart", referring to the tusks.
Walruses mate in the water and give birth on land or ice floes. They feed in the water, diving to depths of 300 ft (90 m), sometimes staying under for as long as a half hour. Clams and mollusks form a large part of their diet. Male walruses compete for territory, often fighting each other; the winners in these fights breed with large numbers of females. Older male walruses frequently bear large scars from these bloody but rarely fatal battles.
Pacific walruses spend the summer north of the Bering Strait in the Chukchi Sea along the north shore of eastern Siberia, around Wrangel Island, in the Beaufort Sea along the north shore of Alaska, and in the waters between those locations.
Smaller numbers of males summer in the Gulf of Anadyr on the south shore of the Chukchi Peninsula of Siberia and in Bristol Bay off the south shore of southern Alaska west of the Alaska Peninsula.
In the spring and fall they congregate in the Bering Strait, adjacent to the west shores of Alaska, and in the Gulf of Anadyr. They winter to the south in the Bering Sea along the eastern shore of Siberia south to the northern part of the Kamchatka Peninsula, and along the southern shore of Alaska.
Walruses have a breeding season in mid-winter, a time spent in the southern Bering sea. The males show off in the water for the females who view them from pack ice. Males compete with each other aggressively for this display-space. Mating probably takes place in the water. After fertilization the fertilized egg remains dormant for several months, then a gestation period of 11 months follows. When a calf is born it is over 3 ft (1 m) long and able to swim. Birth takes place on the pack ice; the calf nurses for about 2 years, spending 3 to 5 years with its mother. Females mature at about 6 years, males at 9 or 10. A walrus lives about 40 years.
Walruses spend about half their time in the water and half their time on beaches or ice floes where they gather in large herds. They may spend several days at a stretch either on land or in the sea. In the sea they sometimes catch fish but generally graze along the sea bottom for clams which they suck from their shells. Abrasion patterns of the tusks show that they are dragged through the sediment, but are not used to dig up prey. Walruses have been observed to attack narwhal.
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