Warm-blooded animals are animals who can control the temperature of their body. This ability is called endothermy or temperature regulation. All mammals and birds are endotherms. The basic source of the heat is chemical energy from the body's metabolism. To this they add a number of temperature-control devices.
- When they are cold they can do things to make themselves warmer. For example, they "shiver", or shake, or run about, or move into a warmer place. This is because all movement by animals creates heat from the chemical reactions of respiration. So polar bears do not freeze because their metabolism produces heat, and movement produces more heat. During hibernation bears exist several degrees lower that they do in active life. Of course, warm-blooded animals have thermal insulation: hair, feathers, or in water blubber (thick fat). These adaptations help keep heat energy inside the animal.
- When they are warm they sweat to become cooler, or pant or open their feathers, or move to a less hot place and lie down.
Warm blooded animals are called endotherms, homeotherms or homoiotherms; cold-blooded animals are poikilotherms.