How do species regulate their temperature?

Cold-blooded and warm-blooded species: how and why they regulate themselves in different ways

by Lorenzo Ciotti
How do species regulate their temperature?
© John Moore / Staff Getty Images News

To produce heat, an endothermic organism must make its cells work and, consequently, the amount of heat produced by an organism in a certain time is proportional to its volume. If, as normally happens, the body temperature is higher than the ambient temperature, the heat lost in a certain time is proportional to the surface of the body and to the difference in temperature between it and the environment. This, as I said at the beginning, concerns endothermic organisms. It is typical only of mammals, birds and probably, of the ancestral forms of these two, Therapsids and Dinosaurs.

They have feathers, which form the plumage, and hair, which form the fur, insulating layers that make the body temperature less influenced by the ambient temperature, thanks to the layer of insulating air that forms between them and the skin. The activity of their cells can be regulated in order to produce more heat, if necessary. They can also dilate the capillaries under the skin to better disperse body heat, or close a large part of them to retain it.

Polar bear cub
Polar bear cub© Andreas Rentz / Staff Getty Images News

Mammals are also able to lose heat through sweat that, evaporating, takes it away from the skin, or by panting, if the fur is thick, with water evaporating from the respiratory system or the tongue. These adaptations allow them to be in an optimal state even in cold periods, always maintaining a higher temperature than ectotherms.

All invertebrates, fish, amphibians and reptiles on the contrary, are cold-blooded, due to the process of Ectothermy. Exposure to the Sun, escape to the shade, variation of depth for aquatic organisms: these are the ways to channel heat into their body.

Blue iguana
Blue iguana© David Rogers / Staff Getty Images News

Consequently these animals are not suited to all types of climates, and do not adapt well to excessive changes in temperature, even if slow. They are generally forced to remain inactive during periods of extreme cold: in fact, temperatures that are too low limit the speed of their metabolism. The advantage, however, is that they do not have to feed as much as Endotherms, since the biomass consumed by them is burned to produce heat, and not stored as future energy reserves.

Finally, plants are ectotherms but there are still mechanisms that allow them to regulate their temperature: for example, through the phenomenon of transpiration, the water evaporated by the stomata lowers the temperature of the plant.