One of the most important examples of homeostasis is the regulation of body temperature. Not all
animals can do this physiologically. Animals that maintain a fairly constant body temperature (birds
and mammals) are called endotherms, while those that have a variable body temperature (all
others) are called ectotherms. Endotherms normally maintain their body temperatures at around 35
- 40°C, so are sometimes called warm-blooded animals, but in fact ectothermic animals can also
have very warm blood during the day by basking in the sun, or by extended muscle activity 9e.g.
bumble bees, tuna).