Mammals are unique among vertebrates in that they possess a body covering made primarily of hair or fur. This covering serves several important purposes, including insulating the body to maintain a stable internal temperature, providing protection against environmental elements, and playing a role in sensory perception.
Hair is made of a protein called keratin, the same substance that forms our nails and the outer layer of our skin. While the density and type of hair can vary greatly among different mammalian species—ranging from the thick fur of arctic foxes to the sparse hair of some elephants—it is often designed to suit the specific habitat and lifestyle of the animal.
In addition to hair, mammals also have another form of body covering called skin, which often contains glands that secrete oils and sweat to aid in temperature regulation and hydration. Some mammals, like whales and dolphins, may have reduced body hair but rely on a layer of blubber for insulation. Overall, the body covering of mammals is a crucial adaptation that supports their survival in a wide range of environments.