poi·ki·lo·therm / poiˈkēləˌ[unvoicedth]ərm; -kil-/ • n. Zool. an organism that cannot regulate its body temperature except by behavioral means such as basking or burrowing. Often contrasted with homeotherm; compare with cold-blooded.DERIVATIVES: poi·ki·lo·ther·mal / ˌpoiˌkēləˈ[unvoicedth]ərməl; -ˌkil-/ adj.poi·ki·lo·ther·mic / ˌpoiˌkēləˈ[unvoicedth]ərmik; -ˌkilə-/ adj.poi·ki·lo·ther·my n.

poikilotherm (exotherm) Organism that regulates its body temperature by behavioural means, e.g. by basking or burrowing. Such animals are often termed ‘coldblooded’, although when active their body temperature is little different from that of homoiothermic (‘warm-blooded’) animals. Poikilothermy is characteristic of lower vertebrates (fish, amphibians, and reptiles), but not of birds and mammals.

poikilotherm(exotherm) An organism whose body temperature varies according to the temperature of its surroundings. Fish are poikilotherms. Compare ectotherm. See also endotherm and homoiotherm.

poikilotherm (exotherm) An organism whose body temperature varies according to the temperature of its surroundings. Fish are poikilotherms. Compare ECTOTHERM.