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Polar Bear

Ursus maritimus
Anatomy

Polar bears are uniquely adapted for life in icy habitats. They are covered in thick fur and a layer of blubber that helps prevent heat loss. The fur is transparent and scatters and reflects light, the way light reflects off snow and ice. Their paws are perfectly designed for roaming the Arctic, measuring up to 12 inches (31 centimeters) to help distribute weight while walking on ice and helping them to swim. Polar bear skin is black, including the black footpads on the bottom of their paws covered in small bumps that help the bears grip the ice, along with fur between their toes and claws. Polar bears have small ears and a round tail to help conserve heat. They move slowly and methodically to help conserve energy. Unlike brown bears, males and non-breeding females do not hibernate in winter. Polar bears are solitary animals, except during breeding and cub rearing season. At birth, polar bear cubs weigh about a pound. Adult males weigh 775-1300 pounds (350-600kg) and females 330-650 pounds (150-295kg).

Habitat

Polar bears are only found in the Arctic, including Alaska, Canada, Russia, Greenland and Norway. They depend on older stable packs of ice, where they spend much of their time hunting, mating and living. The edges of the packs of ice, where there is continual melting and refreezing, and open spaces between ice and ocean are where polar bears find the greatest number of seals.

Diet

Polar bears are the largest land carnivores and on the top of the food chain in the Arctic region. They feed almost exclusively on ringed seals and bearded seals. The remains of these seals provide food for other species in the ecosystem. Polar bears travel great distances in search of food.

Threats

The biggest threat to polar bears throughout their range is the loss of Arctic ice due to climate change. Increased concentrations of greenhouse gases in the atmosphere cause increasing global temperatures, and greatly increase sea ice melting within the Artic. Polar bears that have continuous access to sea ice during the year are able to hunt. As global temperatures rise, there are increased areas where sea ice melts during the summer, forcing polar bears to spend months on land where they live off their stored fat reserves until they are able to hunt. Sea ice loss also means a lower rate of survival for polar bear cubs and increases in drownings. The International Union for Conservation of Nature (IUCN) lists polar bears as a vulnerable species, citing sea ice loss due to global climate change as the biggest threat to these bears. Scientists predict that at the current rate, two-thirds of the world’s polar bears could disappear within this century.

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