What is one of the most amazing organs in your body? Here are some clues: it keeps you dry, safe, and healthy. And it warms up and cools down all by itself. If you guessed your skin, you're right! Humans all pretty much have the same skin—it's made of all the same molecules and it performs the same functions. It covers our bones and muscles and tissues and organs.
But animals and birds have completely different kinds of skin. Some animals, like polar bears, have dense fur that keeps them warm in cold climates. Other animals have no hair, such as Chihuahuas and seals. Chihuahuas live in warm climates, and seals have layers of fat called blubber that keep them warm in cold ocean water. Fish have scaly skin that helps them move through water. Birds have feathers that are specially designed to help them fly.