Endotermisten

Endotermisten are animals that regulate their body temperature primarily via internal heat production from metabolic processes, maintaining a relatively constant core temperature across a range of environmental conditions. In most classifications, endotermisten correspond to the groups of mammals and birds; some exceptions exist among fishes and other taxa that show regional endothermy or transient thermogenesis.

Heat is generated by cellular metabolism, basal metabolic rate; shivering; non-shivering thermogenesis mediated by brown adipose tissue, especially in infants and some hibernating species. Thermoregulation also involves insulation (fur in mammals, feathers in birds), vasoconstriction or vasodilation to adjust heat loss, and evaporative cooling through sweating or panting. Behavioral strategies such as seeking shade or sun also play a role.

Endotermisten typically have higher metabolic rates and energy requirements than ectotherms. This allows broad geographic distribution and activity at cooler temperatures, but increases food intake and risk of overheating in hot conditions. Many endotherms exhibit daily or seasonal variations in activity and temperature, such as torpor and hibernation, to conserve energy.

Evolution of endothermy is a key feature in vertebrate history. It provides advantages in sustained activity, endurance, and colonization of diverse habitats, but entails substantial energetic costs. The term is widely used in comparative physiology and ecology to distinguish internally heated animals from ectotherms, or cold-blooded species.