Homeothermy

The group that includes mammals and birds, both "warm-blooded" homeothermic animals (in red) is polyphyletic.

Homeothermy, homothermy or homoiothermy[1] is thermoregulation that maintains a stable internal body temperature regardless of external influence. This internal body temperature is often, though not necessarily, higher than the immediate environment[2] (from Greek ὅμοιος homoios "similar" and θέρμη thermē "heat"). Homeothermy is one of the 3 types of thermoregulation in warm-blooded animal species. Homeothermy's opposite is poikilothermy. A poikilotherm is an organism that does not maintain a fixed internal temperature but rather its internal temperature fluctuates based on its environment and physical behaviour.[3]

Homeotherms are not necessarily endothermic. Some homeotherms may maintain constant body temperatures through behavioral mechanisms alone, i.e., behavioral thermoregulation. Many reptiles use this strategy. For example, desert lizards are remarkable in that they maintain near-constant activity temperatures that are often within a degree or two of their lethal critical temperatures.

  1. ^ McNab, Brian K. (1978-01-01). "The Evolution of Endothermy in the Phylogeny of Mammals". The American Naturalist. 112 (983): 1–21. doi:10.1086/283249. ISSN 0003-0147. S2CID 84070652.
  2. ^ Ivanov, K.P. (2005). "The development of the concepts of homeothermy and thermoregulation" (PDF). Journal of Thermal Biology. 31 (1–2): 24–29. doi:10.1016/j.jtherbio.2005.12.005. Archived from the original (PDF) on 2017-02-25. Retrieved 2017-02-25.
  3. ^ "33.3C: Homeostasis - Thermoregulation". Biology LibreTexts. 2018-07-16. Retrieved 2021-01-30.