Editing Endotherm (section)

{{Short description|Organism that maintains body temperature largely by heat from internal bodily functions}}
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An '''endotherm''' (from [[Ancient Greek|Greek]] ἔνδον ''endon'' "within" and θέρμη ''thermē'' "heat") is an organism that maintains its body at a metabolically favorable temperature, largely by the use of heat released by its internal bodily functions instead of relying almost purely on ambient heat. Such internally generated heat is mainly an incidental product of the animal's routine [[metabolism]], but under conditions of excessive cold or low activity an endotherm might apply special mechanisms adapted specifically to heat production. Examples include special-function muscular exertion such as [[shivering]], and [[Uncoupler|uncoupled]] oxidative metabolism, such as within [[brown adipose tissue]].

Only [[bird]]s and [[mammal]]s are considered truly endothermic groups of animals. However, [[Argentine black and white tegu]], [[leatherback sea turtle|leatherback sea turtles]], [[Fish#Endothermy|lamnid sharks, tuna and billfishes]], [[cicadas]], and [[Operophtera brumata|winter moths]] are [[Mesotherm|mesothermic]]. Unlike mammals and birds, some reptiles, particularly some species of [[Pythonidae|python]] and [[tegu]], possess seasonal reproductive endothermy in which they are endothermic only during their [[reproductive season]].

In common parlance, endotherms are characterized as "[[warm-blooded]]". The opposite of endothermy is [[ectothermy]], although in general, there is no absolute or clear separation between the nature of endotherms and ectotherms.