Advantages and disadvantages of 'cold-blooded' species

Ectothermy in animal species: what it is, what it is for, what are the disadvantages and advantages of the species that use it

by Lorenzo Ciotti
Advantages and disadvantages of 'cold-blooded' species
© David Rogers / Staff Getty Images News

Ectothermy is a type of thermoregulation that depends on the external environment, a characteristic possessed by some invertebrates, fish, amphibians and reptiles. Reptiles in particular must necessarily spend several hours in the sun to be able to increase their body temperature, especially lizards and snakes.

Snakes and lizards, taking advantage of the sun on rocks. Fish, swimming in depth depending on the water temperature. Desert animals, taking advantage of the sand during the day. Insects, warming their muscles by vibrating their wings. Ectothermic animals often have a more complex metabolism than endothermic animals. For an important chemical reaction, they can have systems of 4 to 10 enzymes that operate at different temperature levels. Therefore, ectothermics often have more complex genomes than homeothermic animals of the same ecological niche.

Snake© Matt Cardy / Stringer Getty Images News

Because of their variable metabolism, ectothermic animals are not well adapted to complex systems that have particular energy needs and a very constant temperature, such as the brain. Some large ectotherms, thanks to a favorable volume/surface ratio, are able to maintain a relatively high body temperature and a high rate of metabolism. This phenomenon, called gigantothermy, has been observed in sea turtles and was probably exploited by most dinosaurs and ancient marine reptiles.

In the presence of optimal temperatures they are able to have an optimal metabolism without wasting energy for their thermoregulation. They have a greater capacity to withstand periods of food shortage and therefore fasting and a longer overall lifespan. On the contrary, they are vulnerable to temperature variations, cannot live in cold environments and icy areas and have lower physical performance in terms of resistance.

Snake© David McNew / Staff Getty Images News

These animals are not adapted to all types of climates, and do not adapt well to excessive temperature changes, even if slow. They are generally forced to inactivity during periods that are too 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 these is burned for heat production, and not stored as future energy reserves.