Odobenus rosmarus

The walrus (Odobenus rosmarus) is a species of pinniped mammal in the family Odobenidae. It is large and lives in arctic seas. There are two subspecies, the Atlantic walrus (Odobenus rosmarus rosmarus) and the Pacific walrus (Odobenus rosmarus divergens). The world population of walruses is estimated at around 250,000. copies.

The walrus belongs to the order Carnivora and to the suborder (or, according to others, superfamily) Pinnipedia.

Name

The Latin name Odobenus comes from the Greek odous ("tooth") and baino (to walk), since Walruses were observed to use their tusks to propel themselves out of the water. Rosmarus comes from the Swedish word meaning walrus. Divergens ("divergent") refers to the fangs.

The Spanish word "walrus" It comes from Lapp or Finnish and came to Spanish through French or English. In the latter language, however, the older word, "morse", fell into disuse and was replaced by the current one, "walrus", which comes from the Danish "hvalros& #34;, meaning "whale-horse" or "sea cow" and is common to other Germanic languages. The Eskimos call it "aivik" in Inuit and, in Yupik, "aivuk".

Subspecies

Two subspecies of walrus are recognized,

• Odobenus rosmarus rosmarus
• Odobenus rosmarus divergens

The Atlantic walrus (Odobenus rosmarus rosmarus) inhabits a region from the Canadian Arctic to the Kara Sea. About 22,500 individuals are believed to exist today (6,000 in Russia and Norway, 12,000 in Canada, and 4,500 in Greenland).

The Pacific walrus (Odobenus rosmarus divergens) is found in the northern Pacific Ocean, from the eastern Siberian Sea to the Beaufort Sea, as well as in the Laptev Sea. There are at least 200,000 Pacific walruses on the coasts of Russia and the United States.

The Pacific walrus is somewhat larger: the male can weigh up to 1,800 kg and has the longest tusks and broadest skull. The largest known specimen weighed 2,265 kg and measured 4.91 m in length. It is kept in the Horniman Museum in London.

Description

As for the size, it is different according to the subspecies. Pacific walruses are slightly larger: males weigh 800-1,700kg and are 2.7-3.6m long, while females weigh 400-1,250kg and are 2.3-3m tall.,1 m. Among the pinnipeds, only some elephant seals reach a larger size.

They have very thick skin, between 2 and 4 cm thick. The skin of the males often presents large nodules, which do not appear in the females. Since they appear at the time of puberty, it seems that it is a secondary sexual characteristic. Hair covers the entire body, except for the fins. Males shed their hair annually, between June and August, while females can take even longer to shed. Walrus fur changes color with temperature: in water they are a pale gray, almost white, in cold water, but they take on a pinkish hue in warm water, due to dilation of the blood vessels in the skin and the increased circulation.

Both males and females have two large tusks that can reach a meter in length and are their most distinctive feature. Their extremities are fins, which are hairless and covered with thick, rough skin, which makes it easier for them to move on land.

Fossils of Odobenids, similar to modern walruses, have been found dating to the middle Miocene, about fourteen million years ago.

Life Cycle

Moorish breeding in captivity

Walruses can live up to forty years. They feed in the water, diving to depths of 90 m, since they are capable of staying under water for half an hour. They feed mainly on clams and other molluscs, although they can also eat other invertebrates, such as: worms, gastropods, cephalopods and even some species of fish.

Although males reach sexual maturity between the ages of six and nine, they usually do not have the opportunity to mate until they reach full physical development (around fifteen years of age) and are able to compete with other males for females. Males compete for territory and often engage in combat; the winners mate with a large number of females.

Females, for their part, also reach sexual maturity between six and nine years of age. They mate in the water. After fertilization, the egg remains dormant for months. The gestation period proper is eleven months, but fifteen or sixteen months elapse from the time of mating to delivery. They give birth to a single young on land or on ice blocks. Newly hatched calves weigh between 45 and 75 kg and are nursed for a maximum period of two years, generally in the water, spending three to five years with their mothers. Mothers are extremely protective of their young.

The main predators of the walrus are polar bears and killer whales. Man has hunted walrus since at least the 9th century century.

Distribution

Walruses inhabit various areas of the circumpolar zone that are barely related to each other. Pacific walruses are found in the seas of: Bering, Chukotka and Laptev and those of the Atlantic in coastal areas of northeastern Canada, Greenland and Russia.

Pacific walruses migrate seasonally due to the extension of the polar cap. Some walruses travel up to 3,000 km in these movements. They spend the winter in the Bering Sea and the summer in the Chukchi Sea.

Relationship with the human being

For the Inuit, the walrus has had important religious significance since ancient times. In addition, it has played a decisive role in all areas of the life of this people, since they obtained meat and oil from it and its fangs, as well as the rest of their bones, provided them with invaluable construction material in a climate in which that trees are very scarce; Walrus stomachs with Cardium molluscs are still considered a delicacy today. The hunting of the walrus carried out by the Inuit, however, was for mere subsistence and did not pose any danger to the species. Even today Inuit are allowed regular subsistence hunting quotas in Canada, Russia and Greenland.

When Europeans reached the southern Arctic seas in the 16th century, the walrus was first seen in It was about to disappear as a species because it began to be the object of intensive hunting, especially because of the ivory used for its defenses, the quality of which is only inferior to that obtained from elephants. Walruses inhabited the east coast of North America, as far as Cape Cod and in the Gulf of St. Lawrence. Several thousand walruses were killed annually in this area in the 16th and 17th centuries. By the 19th century there was not a single specimen left south of Labrador. In search of as yet undiscovered walrus colonies, the hunters then went into more and more remote regions. An idea of the proportions of the kills can be given by the fact that between 1925 and 1931 alone, around 175,000 walruses were hunted on Baffin Island, in the Canadian Arctic. The Atlantic walrus was for this reason on the verge of extinction and, for unknown reasons, its populations have not yet recovered: only 15,000 Atlantic walruses survive today, a tiny fraction of the original population.

Pacific walrus were subjected to similar massacres, although hunting began at a later date. However, its populations have recovered significantly thanks to the protectionist measures introduced by the United States and Russia and today it has again around 200,000 specimens. For this reason, the species as a whole is not in danger of extinction.

Pollution also affects walruses, which are especially sensitive to oil spills, since hydrocarbons are deposited on the seabed, where the walruses find their food, thus reducing the number of their prey.