The Caribou, also known as the reindeer, lives on the very northern parts of the world. They inhabit the Arctic Tundra, North Pole, and regions that include parts of North America, Europe and Asia. The caribou's hooves adapt to the seasons; during summer their footpads become more sponge like to give them a bigger surface area on the damp ground. During winter, their footpads shrink and tighten, exposing the edge of their hoof to cut into the ice and snow to help give them traction. The caribou travels the furthest of any land mammal with migrations containing thousands of caribou. They can also run up to 50 mph and as much as 3,000 miles in a year.