homeothermy

Maintenance of a constant body temperature in endothermic (warm-blooded) animals, by the use of chemical processes to compensate for heat loss or gain when external temperatures change. Such processes include generation of heat by the breakdown of food and the contraction of muscles, and loss of heat by sweating, panting, and other means.

Mammals and birds are homeotherms, whereas invertebrates, fish, amphibians, and reptiles are cold-blooded or poikilotherms (see poikilothermy). Homeotherms generally have a layer of insulating material to retain heat, such as fur, feathers, or fat (see blubber). Their metabolism functions more efficiently due to homeothermy, enabling them to remain active under most climatic conditions. See also temperature regulation.