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? 發問於 科學及數學生物學 · 1 十年前

walrus

can you give some imformation of walrus, answer in engilish please!!!!!!!!

1 個解答

評分
  • 1 十年前
    最愛解答

    Life cycle

    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 time either on land or in the sea. Diving to depths of 90 m (300 ft), they sometimes stay under for as long as a half hour. In the sea they sometimes catch fish, but generally graze along the sea bottom for clams which they suck from the shell. Abrasion patterns of the tusks show that the tusks are dragged through the sediment but are not used to dig up prey. Walruses can also spit jets of water to look for clams. Clams and mollusks form a large part of their diet. Large male walruses have been observed to attack seals if they cannot find any other food source.

    Walruses mate in the water and give birth on land or ice floes. Breeding season is in mid-winter. 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; 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. After fertilization the egg remains dormant for several months, then a gestation period of 11 months follows. When a calf is born, it is over 1 m (3 ft) long and able to swim. Birth takes place on the pack ice; the calf nurses for about 2 years and spends 3 to 5 years with its mother. Females mature at about 6 years, males at 9 or 10. A walrus lives about 50 years.

    Walruses have only three natural enemies: humans, orca, and the polar bear. Polar bears hunt walruses by rushing at them, trying to get the herd to flee, then picking off calves or other stragglers. Walruses have been known to kill polar bears. The walruses use their long tusks (elongated canines) for fighting and for display.

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