Skin and hair cover a mammal's body. Some mammals have horns, claws and hoofs. The hair or fur of a mammal has many functions. The colour often blends in with the world around them and allows them to hide from their enemies. Some mammals produce needles or sharp hair that protects them from attack. But the main function is to keep the body warm.
A mammal's skeleton is made up of three parts:
Mammals have a four-chambered heart system that pumps blood into all parts of their body. The blood brings oxygen to muscles and tissue. The red blood cells of mammals can carry more oxygen than many other animals. Because mammals have a high body temperature they must burn a lot of food.
Mammals digest food through their digestive system. After food is eaten through the mouth it goes down the throat into the stomach and passes through the intestines. Mammals that eat plants have a complicated system with long intestines that help break down food. Flesh is easier to digest so meat-eating mammals have a simpler stomach.