The Arctic fox, also known as the polar fox, is a small fox native to cold Arctic regions of the Northern Hemisphere. It is common in all three tundra biomes. The Arctic fox has evolved to live in the most frigid extremes on the planet. Among its adaptations for cold survival are its deep, thick fur, a system of countercurrent heat exchange in the circulation of paws to keep them from freezing, and a good supply of body fat. Arctic foxes will eat pretty much anything. Their prey includes voles, lemmings, hares, ground squirrels, and bird eggs. Foxes living on the coast also eat shellfish, sea urchins, dead seals and fish, beached whales, and nesting seabirds. In winter when food is scarce, they may follow a polar bear and after the bear makes a kill, eats and leaves, they will steal what ever scraps of meat are left.