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The Polar Bear
If this lumbering creature sometimes seems bow-legged and pigeon-toed, that's because it is. The polar bear (Ursus maritimus) has adapted its stance to provide surer footing for the furred soles of its paws on the slippery Arctic snow and ice of its year-round habitat. Its powerful front legs and paws also provide all the power it needs to cruise through frigid Arctic waters at up to six miles per hour over great distances. There have been sightings of polar bears at sea 200 miles from the nearest land or pack ice. Considering that this mighty creature is Earth's largest land carnivore (though it may spend more of its life in water), with males tipping the scales at up to 1,500 pounds, and towering to a standing height of up to 11 feet, its swimming capabilities seem even more awesome. (Plenty more pets at rickzworld.)
Polar bears are solitary animals (except when breeding), and throughout winter months typically roam the pack ice rimming the southern edge of the planet's Arctic ice cap, hunting their primary prey, Bearded and Ringed Seals. Catching unsuspecting seals surfacing to breathe, or the occasional animal at rest on the ice, the polar bear will dispatch its prey with a crushing blow or bite to the head, then consume its fat and skin, often leaving the remaining meat for their young or for other carrion eaters. In warmer months of late summer and autumn, the bears will expand their diet to include eider ducks, arctic foxes, lemmings, whale or walrus carcasses, and even some vegetation or berries. Their acute sense of smell enables them to register carrion from a distance of up to 20 miles, and to locate seal dens carved deep within the snow. It also enables them to smell seals through pack ice; at times they will use their powerful forelegs as piledrivers to punch through ice to reach the seals. On occasion, these solitary animals may group for feeding on a large find.
Springtime is mating season, with males seeking out available females, who typically breed only every third season. Intervening seasons are spent in the company of and raising the previous litter, most often a litter of two cubs. The fetuses will be carried for 7 to 8 months of gestation, and at birth will be blind, deaf, hairless, weighing but a pound or two (about the size of an average rat). The cubs must nurse for better than 2 years, but will grow and put on weight rapidly, reaching sexual maturity in just 3 to 5 years. Female polar bears are smaller than males, topping out around 600 pounds or so (but close to 1,000 pounds when pregnant). The female bears will build multi-chamber dens for themselves and their young deep within snowbanks or permafrost; the dens can be up to 40 degrees warmer than the outside air temperature. The female bear will enter a state of near hibernation until her cubs are born. Polar bears, whether during pregnancy or during poorer hunting seasons, can sustain themselves for month upon month of fasting, living off their fat reserves.
In addition to its fur-covered soles and unusual stance, the polar bear has made many other physical adaptations to its frigid habitat. Its large size increases the ratio of internal volume to external, and therefore exposed, surface area, enabling it to maintain core body temperature as a warm-blooded animal by minimizing heat loss. Its diet, heavy in fat, allows it to maintain substantial insulating bulk. Its legs are stocky, and its ears and tail small, all to conserve body heat. Its feet are broad (almost 1 foot square), to distribute its body weight upon potentially fragile snow and ice, and to serve as substantial paddles for swimming. And, despite its appearance, the polar bear is not white but black. Its hide is black, and is covered not in white, but in crystalline, hairs that merely appear white by reflecting the colors of surrounding snow and ice. These hairs may act as miniature prisms, bouncing essential warming sunlight down toward the creature's black, heat-absorbing skin. These guard hairs also create an insulating and water-shedding layer that is effective at blocking the penetration of frigid Arctic water. The bears will immediately shed water upon regaining the pack ice after a swim. They will also save energy by sliding on their bellies down long snow-covered slopes. As a further adaptation in hunting, polar bears will reportedly sometimes cover their dark snout with a paw, maintaining concealment against the snow as they stalk prey.
Known as nanook by the Inuit and Yupik peoples, the creature has been variously referred to as the white bear or the ice bear. It is closely related to the similarly-sized Kodiak bear. The Polar Bear has long been an important element of the commerce, culture and folklore of native Arctic peoples. Many legends cast the polar bear as almost human-like in character, and some suggest human and polar bear spirits can be interchangeable. As far back as 3,000 years ago, the bears provided meat, clothing, tools, talismans and art subjects to the Inuit, the Yupik, the Nenets and the Chukchi peoples. Today, the polar bear is depicted on the $2 Canadian coin, and license plates in portions of Canada are shaped like polar bears. The creature was made mascot of the 1988 Winter Olympic Games in Calgary, and is a symbol used to brand and advertise many products worldwide. Polar bears perennially occupy a position of one of the most sought-after attractions at many zoos around the globe.
It is estimated that there is an endangered or threatened population of no more than 25,000 polar bears worldwide, with 70% of those residing in North America. The most serious threat to the bears is global warming, as it leads to the break-up and disappearance of the edge pack ice that is the creature's sole hunting ground. However, as a predator at the top of the food chain, the animals are also subject to pollution, as toxic substances (from pesticides to PCBs to heavy metals to halocarbons) concentrate in their fat and that of their prey. Other threats include overhunting and disruption of their habitat due to the spread of oil and gas development.
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