1/16/2024 0 Comments Who are a polar bears predatorsPermanent, multi-year ice that doesn’t ever melt is more important to polar bears than the annual ice that melts and reforms every year this multi-year ice is increasingly rare, but will likely persist for longer in the island archipelago of northwestern Canada than in Alaska or off the northern coast of Russia. During periods of ice breakup, polar bears frequently swim between floating ice islands. These long swims and storms are also often difficult for cubs. However, if a storm kicks up during these increasingly long swims (caused by the warming ocean), they can drown. Polar bears are excellent swimmers, and they travel long distances between shore and the sea ice if necessary. They will spend time on land when sea ice is not available (and most pregnant polar bear females make their dens on shore near the coast). Polar bears depend on the sea ice, which forms above the open waters where their seal prey lives. Polar bears live in Alaska, Canada, Russia, Greenland, and some northern islands owned by Norway, such as Svalbard. There are some populations south of the Arctic Circle in the Hudson Bay of Manitoba, Canada. Most polar bears occur north of the Arctic Circle to the North Pole. The cubs would otherwise freeze to death in the frigid temperatures of the far north. Pregnant female polar bears must den so that their tiny newborn cubs are born in a warm protected environment dens can be 38 degrees Fahrenheit warmer than the outside temperature. The exception to this is pregnant adult females. In contrast, most polar bears have access to their food of choice (seals) all winter long, so there is no need for them to den. When grizzly bear food is covered in snow during the winter, this species must den because there is nothing to eat. Polar bears have evolved something else that is different from their ancestor: most polar bears don’t den, however all brown bears do. Unlike the massive polar bear, which can grow huge on a diet of abundant seals, its ancestor in the Arctic is small, has very lower reproductive rates, and eagerly eats almost anything that exists in its environment. The polar bear evolved one to three million years ago from the brown bear, which still ekes out a marginal life along the northern shore of the Arctic oceans. The webbed feet results in making polar bears, unlike other bear species, considered to be “marine mammals” along with seals, sea lions, walruses, whales, and dolphins. The wide paws prevent sea ice from breaking by distributing the polar bear's weight as it walks. Polar bears have strong legs and large, flattened feet with some webbing between their toes, which helps with swimming and walking on ice. The polar bear's footpads have a kind of “non-slip” surface, allowing them to get traction on slippery ice. The bear's large size reduces the amount of surface area that's exposed to the cold per unit of body mass (pounds of flesh), which generates heat. This is especially important while swimming and during the frigid Arctic winter. Polar bears also have a thick layer of fat below the surface of the skin, which acts as insulation on the body to trap heat. The skin under the polar bear's fur is actually black this black is evident only on the nose. The bear's outer layer of fur is hollow and reflects light, giving the fur a white color that helps the bear remain camouflaged. Many of the polar bear's physical adaptations help it maintain body heat and deal with its icy habitat. A newborn polar bear weighs only about 1.5 pounds. Bears can weigh about 50 percent more after a successful hunting season than they do at the start of the next most of this additional weight is accumulated fat. A large male can weigh more than 1,700 pounds, while a large female is about half that size (up to 1,000 pounds). Male polar bears are much larger than the females. They are about seven to eight feet long, measured from the nose to the tip of their very short tail. Polar bears are the largest carnivorous land mammals on Earth.
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