Polar bears live only in the northern Arctic where they spend most of their time on ice floes. They are found in the US (Alaska), Canada, Russia, Greenland and Norway. These areas are viciously cold, with temperatures as low as minus 55 degrees Celsuis and wind speeds of up to 30 miles per hour.

By having a thick layer of fat (blubber) under their skin, the bears can stay warm in the cold environment. Polar bears are warm-blooded mammals, which means that they can regulate their body at the same temperature. Their skin is black, which helps to soak up as much heat from the sun as possible. What's more, their round and compact body shape helps to keep them warm. Polar bears don't have large ears or a long tail, because they lose warmth quickly. Instead they try to weigh as much as possible because large objects lose heat slowly, so the heaviest polar bear stays warmer longer.

Polar bears hunt seals, fish, seabirds and reindeer. They will also eat vegetation and berries in the summer. Polar bears do not need to drink water, as they get all the liquid they need from the food they eat.

 In order for polar bears to stay fat and warm they must eat a lot of food. Polar bears often eat 45 kilograms of seal blubber in one meal. About half of the food polar bears eat is used to keep them warm, which is the same for humans. So the colder the Arctic gets, the more they must eat to keep warm.

Polar bears have an amazing sense of smell, which means that they can smell a dead meal 20 miles away and a live seal one meter under the ice. They are very good swimmers, and use their fat and two layers of dense, oily, water repellent fur to help keep them afloat. They use their large feet as paddles when swimming and when on the ice, their feet are used as snow-shoes.

Polar bear cubs are no bigger than a rat when born.