Polar bears have adapted well to life on the ice, one of few large mammals that have been able to do so. Their fur is thick with a warm undercoat and longer guard hairs above: clear, hollow tubes that transmit the sun's warmth directly to their black skin, where the heat is absorbed. It has a strong, muscular body. Its front paws are broad and there is fur on the undersides of its feet. It has a long neck and so its head can remain above water when it is swimming. Their muzzles are longer and their ears smaller than other bears.
Polar bears live along the icy coasts around North Pole to as far in the south as Hudson Bay. 60% or so of polar bears are in northern Canada, while the rest live throughout Greenland, Alaska, Russia and Svalbard, usually close to the ocean but roaming huge distances across the ice.
Polar bears are solitary except for mating pairs and females with offspring. They may come into competition with each other when there is the chance to scavenge when a seal is killed. In such cases, the smaller bear usually runs away. Polar bears can dive underwater to catch their prey, keeping their eyes open while holding their breath for as much as two minutes. They are inactive for a good part of the time, lying, sleeping, or waiting (still hunting). They spend the rest of the time traveling, either walking or swimming, feeding or stalking prey. They are excellent swimmers and may travel far in search of food.
Most of what Polar bears eat is the blubber and skids of ringed seals. They often leave the rest of the carcass, which becomes an important food source for other animals. They also eat birds, fish, berries, reindeer and sometimes walrus. Carcasses of walruses, seals and even whales can provide a regular source of food for polar bears. They sometimes break into underground seal dens to hunt the pups inside them.
Polar bears are polygynous, and breed mostly between April and May. 9 months or so later 1 - 4 cubs are born in a den which the female has dug into the ground or snow. Females go into their dens at the end of autumn, coming out with their cubs when the severe winter weather is past. Cubs start eating solid food around 5 months old but are not weaned until the age of 2 - 3 years old. Cubs play-fight with each other, wrestling, chasing, baring their teeth and sometimes biting, but without causing harm. Such games are lessons in fighting and defending themselves. Polar bears reach sexual maturity between 5 to 6 years old.
Polar bears are still hunted for fur and meat by the Arctic's native peoples. They are also threatened by drilling for gas and oil, increased shipping activity and pollution from industrial chemicals. But the major threat is climate change and global warming causing the sea ice to melt earlier in the year and forcing the bears to shore before they have built sufficient fat reserves to survive the period of scarce food. It is suggested that Polar bears could be extinct in the wild within the next 30 years.
According to IUCN, as of 2010, between 22,000-31,000 Polar bears are estimated to be roaming near to the North Pole, most being in northern Canada. The ICUN lists the Polar bear as a "Vulnerable".
Polar bears are a top Arctic carnivore. The remains of seals left by polar bears are likely to be an important food source for younger, less experienced bears and Arctic foxes.