Mammals and birds are the main groups of warm-blooded animals. Some very active fish, such as tuna, are also warm-blooded. However, the mechanism that heats their bodies is different from that of mammals and birds.
What is the advantage of being warm-blooded?
The chemical reactions that power the bodies of animals work best at warmer temperatures.
Warm-blooded animals are able to live and move about at any temperature that they experience in their normal environment. They can do this because their internal temperature is always the same. Cold-blooded animals, however, become sluggish as the temperature around them drops, and many will hibernate or migrate in very cold weather.
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