homeothermy

Homeothermy is the condition in which an organism maintains a relatively stable internal body temperature regardless of external environmental temperatures. The term is commonly applied to animals that regulate their core temperature through physiological processes (endothermy) and, in some cases, by behavioral means. Although many homeotherms are endotherms, the concept of homeothermy centers on temperature constancy rather than the specific heat-production mechanism.

Regulation of body temperature involves heat production, heat retention, and heat loss management. Metabolic heat production includes mechanisms such as shivering and, in some mammals, non-shivering thermogenesis mediated by brown adipose tissue. Heat retention is aided by insulation from fur, feathers, or fat and by vasoconstriction to reduce heat loss. Heat loss can be controlled through vasodilation, sweating, or panting. Behavioral strategies—seeking sun or shade, basking, burrowing, or changing activity level—also help maintain a stable temperature.

Most mammals and birds are categorized as homeotherms and typically maintain a narrow core-body temperature range that supports consistent biological function. Some ectothermic animals can sustain relatively constant body temperatures over parts of a day or life stage through behavioral thermoregulation and microhabitat use, but they do not regulate heat internally as reliably as true homeotherms. The concepts of regional or seasonal heterothermy, including torpor and hibernation, describe conditions where body temperature fluctuates.

The evolution of homeothermy offers advantages for stable enzymatic activity and sustained performance across varying environments, though it incurs higher energy demands and requires integrated physiological systems to maintain temperature homeostasis.