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Description"Both male and female walruses have tusks, upper canine teeth that continue to grow throughout their lives. Males' tusks are larger and are used for display and as weapons, usually in competition with other males. Walruses occupy the continental shelf rather than deep water, feeding at depths no greater than 100 m. They eat a large variety of bottom-dwelling invertebrates, from tiny crustaceans to octopuses and large crabs. Walruses breed deep in the Arctic pack ice during the darkness of winter. Females begin breeding at 6-7 years of age, and have just one calf after a long, almost 15-month pregnancy. Males are sexually mature at about 9-10 years, but may not be successful in competing for mates until they are about 15 years old. Humans have exploited walruses for years for their ivory tusks, and also for meat, oil, and hides. Their only other predators are polar bears and killer whales, which mostly take the young."
Adaptation: Most parts of the skull of the Walrus, Odobenus rosmarus, have evolved to accommodate the enormous, heavy tusks. This includes not only the facial bones, which root them and basically make up the whole snout, but also the back of the skull, where the prominent flange of bone in the area of the ear is an attachment site for the major muscles that move this massive head around.
Mammal Species of the World
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