endothermer

Endothermer is a term used to describe animals that regulate their body temperature largely through internal heat production, maintaining a relatively stable internal temperature regardless of the surrounding environment. This thermoregulation allows sustained activity in a wider range of temperatures and is commonly equated with the concept of endothermy. In some contexts, endothermer may be treated as a synonym or variant spelling of endotherm, depending on language or scholarly convention.

Endothermer rely on several physiological mechanisms to generate and conserve heat. Metabolic heat production, including shivering and non-shivering thermogenesis, increases core temperature. Insulation provided by fur, feathers, and body fat reduces heat loss. Blood flow adjustments help retain or release heat as needed, and enzymes in tissues operate optimally within a narrow temperature range. Consequently, endothermers typically exhibit higher basal metabolic rates than ectotherms and require a steady energy intake to sustain heat production.

The classical endothermers are birds and mammals. Some lineages exhibit regional endothermy, where heat is produced in specific body regions to support muscle performance or sensory function, such as in certain large fish and marine mammals. The broader concept of endothermy is sometimes discussed in paleontology for extinct groups suspected of having elevated metabolic rates, though direct evidence is often limited.

Ecological and evolutionary considerations include the advantages of activity in cold environments and wider geographic ranges, balanced against higher energy demands and dietary requirements. Endothermy is viewed as a major physiological strategy that has shaped the ecology, behavior, and diversification of its bearers.