The polar bear is the world's largest bear. Males can weigh over 650 lbs, twice as much as females. They have black skin and clear fur that turns yellow in the summer. Polar bears hibernate in Arctic ice in the winter and eat seals, whales, walruses, sea birds, eggs, fish, rodents and berries. Estimates put the world polar bear population between 21,470 to 28,370 in 1993.