Endotherminen

Endotherminen, or endothermy, is the physiological capability of certain animals to generate and retain heat through metabolic processes, allowing a relatively stable internal body temperature despite changes in the external environment. Endotherms rely primarily on internal heat production rather than environmental heat sources, in contrast to ectotherms whose body temperature follows ambient conditions. Some species also exhibit regional endothermy, where heat is produced or retained in specific tissues such as muscles or the brain.

Heat is produced mainly through cellular respiration, with additional heat generated by shivering and, in many mammals and some birds, non-shivering thermogenesis driven by brown adipose tissue. Insulation from fur, feathers, or fat, as well as physiological adjustments like vasoconstriction or vasodilation, helps regulate heat loss. The hypothalamus acts as the body's thermostat, coordinating responses to maintain core temperature.

Endothermy carries high energetic costs, typically accompanying higher basal metabolic rates and greater daily energy requirements. This trade-off supports sustained activity, endurance, and survival in cold environments, but requires greater food intake and can increase overheating risk in hot climates. Many endotherms also employ behavioral strategies, such as seeking shelter or basking, to aid temperature regulation.

Evolutionarily, endothermy has arisen independently in mammals and birds. Its origins involve complex adaptations in metabolism, circulation, insulation, and behavior, with ongoing research into transitional forms and exceptions, including regional endothermy seen in some fish and marine species. Endothermy remains a defining characteristic that shapes the ecology, physiology, and distribution of endothermic animals.