What is interesting about the fur of some tundra animals?

Many tundra animals have thick, dense fur that helps them withstand the extreme cold of the Arctic environment. The fur acts as insulation, trapping air pockets that provide warmth. Additionally, the fur of some tundra animals changes color with the seasons. For example, the Arctic fox's fur is white in the winter and brown or gray in the summer. This adaptation helps the fox camouflage itself in its surroundings. Additionally, some tundra animals have fur that is hollow or has a spongy texture, which provides extra insulation.