Thermoregulation

Thermoregulation is the ability of an organism to maintain its body temperature within a certain range even when the ambient temperature is very different from these limits.

Endotherms
An endothermic being is an animal that regulates the body temperature, in a typical manner, keeping it at a constant level.

Ectotherms
An ectothermic animal is an organism in which the physiological internal heat sources are relatively small or too insignificant to control their body temperature. Thus, these bodies depend from heat sources from the external environment. Examples of ectotherms are frogs, toads and turtles.

Homeothermic
Animals who are able to maintain a relatively constant body temperature despite large variations in outdoor temperature are called homeothermic.

Poikilothermic
Animals in which the body temperature varies according to the environment are called poikilothermic. Examples of poikilotherms animals include invertebrates and aquatic animals like fishes and amphibians.