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Walrus (Odobenus rosmarus)

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Walruses are easily recognized due to their long white tusks. These pinnipeds live in cold regions in both the Atlantic and Pacific Oceans.

The walrus's scientific name, Odobenus rosmarus, comes from the Latin words for "tooth walking sea-horse."

Description:

Walruses have long tusks that can grow to 3 feet in males and about 2.5 feet in females. These tusks, which are a pair of canine teeth that grow continuously, can be used for dominance or aggression displays, to punch breathing holes in ice, and to assist the walrus in hauling out (which is likely the source of their scientific name, as it may appear as if they are walking on their teeth). Walruses may even sleep by using their tusks to anchor themselves to ice while their body hangs in the water. They also have air sacs in their neck that help them float while keeping their head upright.

Walruses also have long whiskers, a layer of blubber (that is up to 6" thick), a wrinkled appearance, and brown skin. They can grow to about 11.5 feet in length and 2 tons in weight. Their huge size makes them the largest pinniped.

Classification:

  • Kingdom: Animalia
  • Phylum: Chordata
  • Subphylum: Vertebrata
  • Superclass: Gnathostomata
  • Superclass: Tetrapoda
  • Class: Mammalia
  • Subclass: Theria
  • Order: Carnivora
  • Suborder: Caniformia
  • Infraorder: Pinnipedia
  • Family: Odobenidae
  • Genus: Odobenus
  • Species: rosmarus

There are two subspecies of walrus - Odobenus rosmarus divergens (Pacific walrus) and Odobenus rosmarus rosmarus (Atlantic walrus).

Feeding:

Walruses feed near the ocean bottom, and may undertake foraging trips that are several days long. Walruses eat bottom-dwelling shellfish such as clams and mussels. They may also eat tunicates, fish, seals and dead whales. They use their sensitive whiskers to find their food, and they have powerful suction to suck out prey from their shells or the ocean bottom. In one study, captive walruses consumed 2-3% of their body weight in fish each day.

Reproduction:

Walruses become sexually mature at 4-12 years of age. Males may be able to mate when they are as young as 5 years old, but often do not mate until they are physically mature and large enough to compete with other adult males, which may not be for another 10 years.

Mating is thought to take place in the water. The female experiences delayed implantation, in which the embryo doesn't immediately attach to the uterus for 3-5 months. This brings the total gestation period to about 15 months. The female gives birth on the ice to usually 1 calf. The calf is gray to brown in color and weighs 100-165 pounds at birth.

Mothers are protective of their calves, who may stay with their mothers until they are 2 or older.

Walruses are thought to live for 40 years or more.

Distribution:

Walruses live in Arctic and sub-Arctic waters in the Northern Hemisphere. The Pacific walrus subspecies lives in both United States and Russian waters including the Bering, Chukchi, and Laptev Seas. The Atlantic subspecies lives on ice and in the waters off northeastern Canada and Greenland. Sea ice is important for walruses because they give birth, nurse, seek shelter and even float to new areas via sea ice. During the summer in some areas, sea ice has retreated

Status:

The population for walruses worldwide is estimated at about 250,000 walruses (Source: Defenders of Wildlife). There are more Pacific than Atlantic walruses. A 1990 study estimated that there were 200,000 Pacific walruses, and they are currently a candidate species for listing as "threatened" under the Endangered Species Act. Walruses are harvested by natives in the U.S. (Alaska) and Russia for food, ivory (tusks), bones and their hides. Since the 1960's, 3,200 to 16,000 walruses have been harvested per year. Other threats to walruses include decreasing sea ice, pollution, and human disturbance from airplanes and vessels.

References and Further Information:

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