What does poikilothermy mean?
Poikilothermy is the condition in which an organism's body temperature varies according to the temperature of its surroundings. It is characteristic of many reptiles, amphibians, fish, insects, and other animals whose body processes are strongly influenced by external heat. An animal displaying this condition may warm itself in sunlight and cool in shade, or become less active when environmental temperatures fall. The opposite condition is homeothermy, in which a warm-blooded animal maintains a relatively stable internal temperature. Poikilothermy is also distinguished from endothermy and heterothermy, which concern the sources of body heat and the degree of temperature regulation more specifically. The word is most often used in biological and ecological research rather than everyday speech.
nounThe condition in which an organism's body temperature varies with the temperature of its surroundings, rather than remaining relatively constant.
- The physiological condition of an organism whose body temperature changes with the temperature of the surrounding environment.
"Reptiles commonly display poikilothermy, becoming warmer in sunlight and cooler in shade."
"Many fishes exhibit poikilothermy, so their body temperatures closely follow the water around them."
"The researcher used temperature sensors to investigate poikilothermy in free-ranging reptiles."
The plural is used when referring to the condition in different organisms, groups, or contexts.
"The study compared poikilothermies across several species of desert reptiles."
A snake basking on warm pavement is displaying poikilothermy: its body temperature rises and falls with its surroundings.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does poikilothermy come from?
Poikilothermy combines the Greek adjective poikilos, meaning “variable” or “various,” with the English form therm, derived from Greek thermē, meaning “heat.” The term was developed to describe animals whose body temperature follows changes in the environment. Its relatives include poikilothermic, describing an organism that exhibits this condition, and poikilotherm, a noun for such an organism.
Related word forms
How poikilothermy is actually used
This is a technical biological term used especially in zoology, ecology, and comparative physiology. It is normally discussed in contrast with homeothermy, in which body temperature remains relatively stable.
Easily confused with poikilothermy
Poikilothermy names the general physiological condition, whereas poikilothermia more specifically refers to the state of having a body temperature that varies with the environment.