polar bear


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polar bear,

large white bearbear,
large mammal of the family Ursidae in the order Carnivora, found almost exclusively in the Northern Hemisphere. Bears have large heads, bulky bodies, massive hindquarters, short, powerful limbs, very short tails, and coarse, thick fur.
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, Ursus maritimus, formerly Thalarctos maritimus, of the coasts of arctic North America, Asia, and Europe. Polar bears usually live on drifting pack ice, but sometimes wander long distances inland. They are powerful swimmers and may cross 20 to 30 mi (30–50 km) of water at a time.

The polar bear's body is long and streamlined, with a long neck and small head. Adult males are 7 to 9 1-2 ft (210–290 cm) long, stand 4 to 4 1-2 ft (122–137 cm) at the shoulder, and weigh 700 to 1,600 lbs (320–730 kg). Females are somewhat smaller. The extremely dense fur appears yellowish white but is in fact unpigmented. Unlike other bears, polar bears have hairy soles, which help them grip the ice. They may attain a running speed of 25 mi (40 km) per hr on ice.

Polar bears are omnivorous, but feed chiefly on marine animals such as seals and young walruses. Quite fearless, they will stalk any animal, including humans. They take advantage of carcasses left by hunters, and in summer eat vegetation on the shore. If food is scarce, their physiology can slow to a state known as walking hibernation.

Except for a brief courtship in summer, polar bears are solitary. Males and nonpregnant females are thought to wander all winter. A pregnant female makes a winter den in the snow; two tiny, helpless cubs are born in January and nursed in the den until March. They usually remain with the mother for about a year and a half, while learning to hunt.

Polar bears have been extensively hunted, especially by Eskimos, for fur, flesh, and ivory, and they have declined greatly in numbers. Although extremely dangerous to humans, they do well in captivity. In recent years, changes in sea ice cover in the Arctic appears to have placed some populations of polar bears under stress, and has led the U.S. government to list the bear as threatened. Polar bears can crossbreed in the wild and in captivity with grizzly bearsgrizzly bear
or grizzly,
large, powerful North American brown bear, characterized by gray-streaked, or grizzled, fur. Grizzlies are 6 to 8 ft (180–250 cm) long, stand 3 1-2 to 4 ft (105–120 cm) at the humped shoulder, and weigh up to 800 lb (360 kg).
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. Polar bears are classified in the phylum ChordataChordata
, phylum of animals having a notochord, or dorsal stiffening rod, as the chief internal skeletal support at some stage of their development. Most chordates are vertebrates (animals with backbones), but the phylum also includes some small marine invertebrate animals.
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, subphylum Vertebrata, class Mammalia, order Carnivora, family Ursidae.

Bibliography

See study by A. E. Derocher (2012).

Polar Bear

 

(Ursus maritimus), a predatory mammal of the bear family; a typical representative of arctic fauna. Polar bears live in the region of floating ice near the Asiatic and American shores of the Arctic Ocean. They are larger than the European brown bear (body length, to 3 m; weight, about 700 kg). The fur is white (with yellowish spots), thick, and long. The soles of the feet are covered with hair.

Polar bears do not hibernate; however, pregnant females hole up in the winter in dens situated on the shore. The bears are excellent swimmers and divers. Their main food is the seal. They usually mate in July; the cubs are born, most often in pairs, in February or March. At birth they are blind and helpless. After a month, when they open their eyes, the female leaves the den and returns to a nomadic way of life. The cubs stay with the female about a year and a half. The bears give birth once every other year. Polar bears are hunted for their hides, which are made into rugs; and for their meat, which is edible. Hunting polar bears is completely forbidden in the USSR; in other countries it is restricted.

REFERENCE

Mlekopitaiushchie Sovetskogo Soiuza, vol. 2, part 1. Moscow, 1967.

polar bear

[′pō·lər ‚ber]
(vertebrate zoology)
Thalarctos maritimus. A large aquatic carnivore found in the polar regions of the Northern Hemisphere.

polar bear

a white carnivorous bear, Thalarctos maritimus, of coastal regions of the North Pole
References in periodicals archive ?
Using high-tech collars that monitored behavior, hunting success and metabolic rates, the researchers followed nine female polar bears without cubs through springtime, as the animals went hunting on sea ice over Beaufort Sea.
The report in the journal Science tracked nine female polar bears in the Arctic's Beaufort Sea during the spring, which is usually prime feeding season.
Summary: Polar bears face an existential threat from climate change due to the loss of habitat from melting sea ice
There may be as few as 26,000 polar bears left in the world.
As a threatened species, polar bears are entitled to peaceful pregnancies, and Hilcorp took measures to ensure the soon-to-be mother bear was not disturbed.
Believe it or not, polar bears have a bigger problem with overheating than with being cold (especially when they are running)
The United States has continued to tighten the screws on Canada's polar bear harvest.
They found that there likely are more than enough calories available on land to feed hungry polar bears during the lengthening ice-free seasons.
The Chukchi-Bering Sea (CS) polar bear population is shared by the United States and Russia.
The Honourable Leona Aglukkaq, Minister of the Environment, Minister of the Canadian Northern Economic Development Agency and Minister for the Arctic Council, will lead the Canadian delegation at the 40th Anniversary of the International Agreement on the Conservation of Polar Bears in Moscow, Russia, from December 4-6, 2013.
The polar bear has thus become a symbol for both sides of the great debate: either they're an image of the extinction we're inflicting on other species, or emblematic of environmental scaremongering.