Walruses are the gentle giants of the Arctic. They are among the largest pinnipeds — fin-footed, semiaquatic marine mammals. However, while they have an intimidating size, and are carnivores, these animals are not aggressive. The walrus is the only living species in the family Odobenidae and genus Odobenus. This species is subdivided into two subspecies the Atlantic walrus , which lives in the Atlantic Ocean, and the Pacific walrus, which lives in the Pacific Ocean.
The walrus (Odobenus rosmarus) is a large flippered marine mammal with a discontinuous distribution about the North Pole in the Arctic Ocean and subarctic seas of the Northern Hemisphere. The walrus has played a prominent role in the cultures of many indigenous Arctic peoples, who have hunted the walrus for its meat, fat, skin, tusks, and bone.
Pinnipeds are seals, sea lions, and walruses. Some scientists classify the pinnipeds as a suborder of the order Carnivora.
Family – Odobenidae
- The odobenids share some characteristics with the other two pinniped families. Morphologically, the walrus is more similar to the Phocidae (true seals). Several studies based on molecular data have linked the walrus more closely to the otariids, yet the pinniped family that the odobenids are most closely allied to is still in question.
- Some researchers divide the Odobenidae into two subfamilies: the Odobeninae (living walruses of the genus Odobenus and six extinct walrus genera) and the Dusignathinae (four extinct walrus genera.
- The earliest of the odobenid fossils dates back to the middle Miocene, about 14 million years ago.
- Scientists theorize that the ancestors of the Odobeninae, or modern walrus, probably made their way from the northern Pacific Ocean to the Atlantic during the late Miocene, about 6.5 million years ago, by way of a Central American seaway.
- Walruses are generally found where the water is no more than 80 m (262 ft.) deep. They prefer a habitat with a gravelly bottom. Walruses spend about two-thirds of their lives in the water.
- Walruses are adapted to a habitat of sea ice and prefer snow-covered moving pack ice or ice floes to land. They haul out on small rocky islands when ice is not present.
- Total world walrus population is about 250,000 animals.
- As the Pacific walrus population grew, annual subsistence catches by indigenous Arctic peoples ranged from about 3,000 to 16,000 walruses per year until about 1990, and then decreased to an average of 5,789 animals per year from 1996 to 2000. Some scientists predict that, without long-term management, natural and human-related mortality factors could rapidly reduce the population once more.
- Most male walruses are sexually mature at about eight to ten years. Successful reproduction, however, probably doesn’t occur until 15 years when a male attains full physical size and is able to compete for females.
- Most females are sexually mature at about five to six years. Successful reproduction probably begins at about ten years.
Longevity and Aging
- Walruses live up to 40 years.
- As a walrus ages, it periodically produces growth layer groups of dental material. Age can be estimated by examining a sliced section of a cheek tooth and counting these layers.