<h2>Endotherms and Ectotherms</h2>
<p>Animals can be divided into two groups: some maintain a constant body temperature in the face of differing environmental temperatures, while others have a body temperature that is the same as their environment and thus varies with the environment. Animals that do not control their body temperature are ectotherms. This group has been called cold-blooded, but the term may not apply to an animal in the desert with a very warm body temperature.</p>
<p>In contrast to ectotherms, which rely on external temperatures to set their body temperatures, poikilotherms are animals with constantly varying internal temperatures. An animal that maintains a constant body temperature in the face of environmental changes is called a homeotherm. Endotherms are animals that rely on internal sources for body temperature but which can exhibit extremes in temperature. These animals are able to maintain a level of activity at cooler temperature, which an ectotherm cannot due to differing enzyme levels of activity.</p>
<p>Heat can be exchanged between an animal and its environment through four mechanisms: radiation, evaporation, convection, and conduction (see the figure below). Radiation is the emission of electromagnetic “heat” waves. Heat comes from the sun in this manner and radiates from dry <a data-lesson="skin" data-subject="biology" data-tutorial="human-biology" href="https://app.ulearngo.com/biology/human-biology/skin">skin</a> the same way. Heat can be removed with liquid from a surface during evaporation. This occurs when a mammal sweats. Convection currents of air remove <a data-lesson="heat-conservation-and-dissipation" data-subject="biology" data-tutorial="animal-body-form-function" href="https://app.ulearngo.com/biology/animal-body-form-function/heat-conservation-and-dissipation">heat</a> from the surface of dry skin as the air passes over it. Heat will be conducted from one surface to another during direct contact with the surfaces, such as an animal resting on a warm rock.</p>
<div class="wp-caption alignnone" style="width: 800px"><img alt="Photo A shows the sun. Photo B shows a sweaty person. Photo C shows a lion with its mane blowing in the wind. Photo D shows a person holding a steaming hot drink." height="617" src="https://data.ulearngo.com/assets/acf0deee-7433-45a9-a1aa-f0dd6183aebd" width="800"/><p class="wp-caption-text">Heat can be exchanged by four mechanisms: (a) radiation, (b) evaporation, (c) convection, or (d) conduction. (credit b: modification of work by “Kullez”/Flickr; credit c: modification of work by Chad Rosenthal; credit d: modification of work by “stacey.d”/Flickr)</p></div>

ad260561-7f24-4cf8-a3f2-b129f5e47c91

Endotherms and Ectotherms

Biology studies life and living organisms. Biology can be divided into different sections that cover the morphology, physiology, anatomy, behavior, and so on of living organisms.

Biology

Learn about animal form and function, including body plans, limits on size and shape, bioenergetics, tissues, and homeostatic processes such as thermoregulation and neural control.


Endotherms and Ectotherms

Track Your Learning Progress

Earlier discussion