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The polar bear has stocky limbs and very short ears that are in accordance with the predictions of Allen's rule, so does the snow leopard. [5] In 2007, R.L. Nudds and S.A. Oswald studied the exposed lengths of seabirds ' legs and found that the exposed leg lengths were negatively correlated with Tm axdiff (body temperature minus minimum ambient ...
The polar bear (Ursus maritimus) is a large bear native to the Arctic and nearby areas. It is closely related to the brown bear, and the two species can interbreed.The polar bear is the largest extant species of bear and land carnivore, with adult males weighing 300–800 kg (660–1,760 lb).
A polar bear and its cub. Animals that are active in the winter have adaptations for surviving the intense cold. [55] A common example is the presence of strikingly large feet in proportion to body weight. These act like snowshoes and can be found on animals like the snowshoe hare and caribou.
Although polar bears spend most of their time on the ice rather than in the water, polar bears show the beginnings of aquatic adaptation to swimming (high levels of body fat and nostrils that are able to close), diving, and thermoregulation. Distinctly polar bear fossils can be dated to about 100,000 years ago.
An Alpine chough in flight at 3,900 m (12,800 ft). Organisms can live at high altitude, either on land, in water, or while flying.Decreased oxygen availability and decreased temperature make life at such altitudes challenging, though many species have been successfully adapted via considerable physiological changes.
Polar bears rely on seals and fish as their primary food source. While the bears can hunt land mammals such as caribou and fox, they can survive off of land prey for only approximately 6 months. Without the abundance of sea ice, polar bears cannot access seals and fish and, thus, can starve. [ 17 ]
Researchers tracked polar bears with GPS system collarsand recorded long-distance swims up to 354 kilometres (220 mi), with an average of 155 kilometres (96 mi), taking up to ten days. [89] A polar bear may swim underwater for up to three minutes to approach seals on shore or on ice floes while hunting.
The key danger for polar bears posed by the effects of climate change is malnutrition or starvation due to habitat loss.Polar bears hunt seals from a platform of sea ice. Rising temperatures cause the sea ice to melt earlier in the year, driving the bears to shore before they have built sufficient fat reserves to survive the period of scarce food in the late summer and early fall.