Walrus

Common Name: Walrus

Class: Mammalia

Order: Pinnipedia

Family: Odobenidae

Genus: Odobenus

Species: Odobenus rosmarus

 

Taxonomy/Description

Walruses belong to the Mammalian Order Pinnipedia, in the family Odobenidae.  Walruses are the only members of this family.  They are easily distinguishable from other pinnipeds by their tusks, which are elongated canine teeth.  The walrus's scientific name is Odobenus rosmarus.  The genus name, Odobenus, means "one that walks with its teeth".  This refers to the walrus's common behavior of dragging itself over ice flows with its tusks.  The specific name, rosmarus, is derived from the Scandinavian name for walrus.

Adult males are 10-12 feet long and can weigh 2,000-3,000 pounds.  Their tusks may reach a length of 3 feet and weigh over 10 pounds.  Females are 7-9 feet long and can weigh 1,500-2,000 pounds.  Several inches of blubber and very thick skin to help keep them warm.  Walruses share anatomical features with sea lions and true seals.  Like Otariids, walruses can turn their hind flippers forward and support their body for walking on land.  But like Phocids, they lack external ear flaps.

Habitat/Diet

The walrus lives in the artic oceans following the ice line as it expands and recedes on a yearly basis.  There it feeds on up to 4,000 clams in one feeding!  Other invertebrates include snails, mussels, starfish, urchins and sea cucumbers.  Walruses unearth food items on the ocean bottom by squirting water out of their mouth.  The stream of water drills the mollusks hidden in the mud.  Walruses also dine on a fish, and there is one record of a walrus feasting on a seal pup.

Behavior/Reproduction

A walrus's tusks are used for many things including defense from polar bears, killer whales, and local hunters.  They also use them for social roles, pulling themselves up onto the ice floes, and to create breathing holes in the ice.    They can dive 300 feet in the water to hunt for prey.  Since there is little light present at depths of 200-300ft, eyesight is not the walrus's primary hunting sense.  Its long whiskers, called vibrissae, are used to feel around the ocean floor for prey species.

On land, they congregate in herds of 100 to over 1,000 animals. Males maintain harems of females.  Walrus calves climb atop their mothers to avoid getting crushed in these large herds.  Walruses bask in the sun to keep warm.  Their skin turns pink as blood rushes to fill the vessels closest to the surface of the skin to warm up.  The males have inflatable air sacs on either side of their necks allowing them to make a bellowing sound.  This sound is used to  warn other males and call females.  These air sacs also fill up with air like floatation devices so that the walrus may vertically bob in the water to sleep.  It is believed that mating takes place in the water.  Female walruses give birth to a single calf on land.  This calf weighs around 100 pounds.  Walruses can live up to 40 years. 

Conservation

There are two subspecies or races of walrus: the Atlantic and Pacific.  The Atlantic race was formerly found as far south as Nova Scotia and occasionally Massachusetts.  This  race is now endangered.  Walrus numbers were reduced drastically by commercial hunters until in 1972, the marine mammal act protected them and made it so that only people native to the land can hunt and kill a certain number of animals.

 

CAC is a program of the Institute for the Study of Human-Animal Relations at Canisius College in Buffalo, NY.