Pacific Walrus

Scientific Name: Odobenus rosmarus

Home: Edge of the Arctic Ice SheetAlaskan and Chukchi Sea, Bristol Bay, and the Bering Sea

   

Imagine an 11 foot long, 2000 pound seal, tusked like an elephant, with the bristly muzzle of a giant otter, the peg-like teeth of a manatee, and the bellow of a buffalo. You’ve got it - a walrus. To the old Norse they were the whale-horse, "hval-hross." So you can see how the Walrus got its name.
Walruses spend half their time in below freezing Arctic waters and the other half lounging on ice floes and shorelines. They have to be able to survive the constant cold. On land, they love to sunbathe on the beach and will lie close together in herds of over a thousand animals. Not only is there safety in numbers but it also helps retain their body heat. In the water their body has adapted to help them stay warm. Walruses deposit most of their body fat into a thick layer of blubber (up to 6 inches thick) that lies just underneath their thick skin (up to one and a half inches thick). This helps cushion their chest and stomach when they walk around on land and protects them from the cold wind and icy water when lying out on the ice or swimming. It also acts as an energy reserve and streamlines the body, helping them swim and dive (sometimes as deep as 300 feet). Another adaptation to the cold is that Walruses have no external ear. It is just a small hole which is hard to see with all of their wrinkles. Just think of your own fingers, toes and ears in the winter. By reducing the number of external appendages, the walruses stay warmer.

Walruses are slow swimmers, averaging only about four and a third miles per hour. But, if they are startled they can swim up to 22 miles per hour. Their forelimbs and hindlimbs are sleek and webbed, like oars. The bottoms of the flippers are bumpy so the walrus can grip the ice and they are able to turn their hind flippers forward to aid in movement on land. They also have special air sacs in their throats that act like life preservers (holding up to 50 liters of air) and let their heads stay above the water - they can even sleep upright in the water this way. Special muscles prevent water from entering the trachea (the tube that carries air to the lungs) when the walrus opens its mouth below water. They can even close their nostrils when resting.
Walruses are carnivores, feeding mainly on invertebrates found at the bottom of the sea. They eat several different kinds of clams, snails, crabs, shrimps, worms, and occasionally seals. Like most marine mammals, they have special physiological adaptations for diving and food gathering. Walruses need about one minute of breathing at the surface for every five to eight minutes of underwater activity, but can remain submerged for as long as ten minutes. To conserve oxygen while it is below water the walrus can slow down their heartbeat while diving. They can also divert blood away from parts of the body that can withstand low levels of oxygen (like their skin and stomach) to the heart and brain where more oxygen is needed. Twelve percent of their body weight is blood ( humans are only 7 percent) which allows them to carry more oxygen. In addition, their oxygen carrying red blood cells are exceptionally large. Their muslces have a lot of the protein called myoglobin, which helps transport and store oxygen in their muscle tissue.

Walruses may look like they have a mustache, but the 700 or so hairs packed on their snout are called vibrissae. They use these sensitive whiskers (up to 11 inches long) to feel their way through the sand and look for food. When prey is detected the walrus will stop and swish its’ head back and forth to dig it out. It uses its vibrissae like ‘chop sticks’ to manipulate its food. If the shellfish is too far below the surface, the walrus has a cool way of uncovering it. It takes in a big mouthful of water and squirts it forcefully, like a water drill, through its tongue at the ocean floor. This moves the sand out of the way exposing a tasty morsel like a clam or worm. Their narrow mouths, strong thick lips, and piston-like tongues allow them to create a strong suction, and rip the fleshy parts of their food away from the shell. A walrus can find and eat a shellfish in about six seconds. This speed allows the walrus to consume plenty of food on a dive.
Walruses are among the strangest living mammals. Their large tusks (averaging 20 inches) make them unlike any other marine animal. These tusks are used in fighting for territory and mates, but they also serve other functions. Tusks can be used for cutting through ice, hooking over ice for stability while sleeping, anchoring themselves on the ocean bottom while digging for clams, and to get a grip when climbing out of the water onto ice. They are often refered to as tooth walkers.

Walruses communicate to each other with knocks, clacks, and whistles, The males use the air sacs at their throats to make a loud bell-like sound during breeding season. Females usually have one baby, which can swim as soon as it's born. At birth the babies weigh 99-165 pounds. Moms are extremely protective of their calves. They will defend and protect the calf and may shelter it under their chest between their foreflippers. Calves often ride on their mothers' backs in the water. Walruses live about 16 to 30 years.

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Thanks to the following websites for the great info.
http://www.nps.gov/bela/html/walrus.htm
http://animaldiversity.ummz.umich.edu/site/accounts/information/Odobenus_rosmarus.html
http://www.seaworld.org/infobooks/Walrus/adapaqwal.html
http://www.biosbcc.net/ocean/marinesci/04benthon/arcwalrus.htm
 
Thanks to the U.S. Fish and Wildlife Service,

and the National Oceanic and Atmospheric Administration for the great picts.