A polar bear is a massive white bear that lives in the Arctic, the frozen region around the North Pole. These are among the largest land predators on Earth: a full-grown male can weigh as much as ten adult humans and stand over ten feet tall on its hind legs.

Polar bears are superbly adapted to their icy environment. Their thick white fur provides camouflage against the snow and ice, helping them sneak up on seals, their primary food. Beneath that fur lies black skin that absorbs heat from the sun, and beneath that, a layer of fat up to four inches thick keeps them warm in temperatures that can drop to fifty degrees below zero. Their huge paws work like snowshoes, spreading their weight so they can walk on thin ice, and the rough pads on their feet give them traction on slippery surfaces.

Unlike some other bears that hibernate through winter, polar bears remain active year-round, traveling vast distances across sea ice to hunt. They're powerful swimmers, using their large front paws to paddle through frigid Arctic waters for hours at a time. A polar bear can smell a seal from nearly a mile away and will wait patiently beside a breathing hole in the ice, sometimes for hours, until a seal surfaces.

Scientists estimate only about 25,000 polar bears remain in the wild today, living in five countries: the United States (Alaska), Canada, Russia, Greenland (Denmark), and Norway.