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Ectotherms are cold-blooded animals that depend on external sources to regulate their body temperature. Learn how ectotherms adapt to different environmental conditions and what are the advantages and disadvantages of being an ectotherm.
- The Editors of Encyclopaedia Britannica
An ectotherm (from the Greek ἐκτός ( ektós) "outside" and θερμός ( thermós) "heat"), more commonly referred to as a " cold-blooded animal ", [1] is an animal in which internal physiological sources of heat are of relatively small or of quite negligible importance in controlling body temperature. [2] Such organisms ( frogs, for ...
- Overview
- Key points
- Introduction
- Endotherms and ectotherms
- Why regulate temperature?
- Temperature balance
- Check your understanding: graphs of metabolic rate
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The difference between endotherms and ectotherms. How to read graphs related to endotherms and ectotherms.
•Most animals need to maintain their core body temperature within a relatively narrow range.
•Endotherms use internally generated heat to maintain body temperature. Their body temperature tends to stay steady regardless of environment.
•Ectotherms depend mainly on external heat sources, and their body temperature changes with the temperature of the environment.
•Animals exchange heat with their environment through radiation, conduction—sometimes aided by convection—and evaporation.
•Radiation: Radiation is the transfer of heat from a warmer object to a cooler one by infrared radiation, that is, without direct contact.
•Most animals need to maintain their core body temperature within a relatively narrow range.
•Endotherms use internally generated heat to maintain body temperature. Their body temperature tends to stay steady regardless of environment.
•Ectotherms depend mainly on external heat sources, and their body temperature changes with the temperature of the environment.
•Animals exchange heat with their environment through radiation, conduction—sometimes aided by convection—and evaporation.
What’s it like outside today? If it’s winter where you are, it might be pretty cold. If it’s summer, it might be pretty hot. Either way, odds are that your core body temperature is right around 98.6∘F /37∘C . As we saw in the article on homeostasis, mechanisms like shivering and sweating kick in when your body gets too cold or too hot, keeping your internal temperature steady.
Not all organisms keep their body temperature in as narrow a range as we humans do, but virtually every animal on the planet has to regulate body temperature to some degree—if only to keep the water in its cells from turning to ice or to avoid denaturing its metabolic enzymes with heat.
People, polar bears, penguins, and prairie dogs, like most other birds and mammals, are endotherms. Iguanas and rattlesnakes, like most other reptiles—along with most fishes, amphibians, and invertebrates—are ectotherms.
Endotherms generate most of the heat they need internally. When it's cold out, they increase metabolic heat production to keep their body temperature constant. Because of this, the internal body temperature of an endotherm is more or less independent of the temperature of the environment.
[What is metabolism?]
This pattern is shown on the graph below: the mouse maintains a steady body temperature close to 37∘C across a wide range of external temperatures.
For ectotherms, on the other hand, body temperature mainly depends on external heat sources. That is, ectotherm body temperature rises and falls along with the temperature of the surrounding environment. Although ectotherms do generate some metabolic heat—like all living things—ectotherms can't increase this heat production to maintain a specific internal temperature.
There are some basic limits on survivable body temperature for most animals. At one end of the spectrum, water freezes at 32∘F / 0∘C to form ice. If ice crystals form inside a cell, they'll generally rupture its membranes. At the other end of the spectrum, enzymes and other proteins in cells often start to lose shape and function, or denature, at temperatures above 104∘F / 40∘C .8
Why do many organisms—including you and me—keep their body temperature in a narrower range than this? The rate of chemical reactions changes with temperature, both because temperature affects the rate of collisions between molecules and because the enzymes that control the reactions may be temperature-sensitive. Reactions tend to go faster with higher temperature, up to a point, beyond which their rate drops sharply as their enzymes denature.
For both endotherms and ectotherms, body temperature depends on the balance between heat generated by the organism and heat exchanged with—lost to or gained from—the environment.
Heat always moves from warmer to cooler objects, as described in the Second Law of Thermodynamics.
There are three main ways that an organism can exchange heat with its environment: radiation, conduction—along with convection—and evaporation.
•Radiation: Radiation is the transfer of heat from a warmer object to a cooler one by infrared radiation, that is, without direct contact.
[May I see an example?]
•Conduction: Heat can be transferred between two objects in direct contact by means of conduction. Conduction of heat between your skin and nearby air or water is aided by convection, in which heat is transferred through movement of air or liquid.
The graph below shows metabolic rate as a function of external temperature for two animals: an endotherm and an ectotherm.
Which curve represents the endotherm, and which represents the ectotherm?
Choose 1 answer:
Choose 1 answer:
•(Choice A)
Curve A represents the endotherm; curve B represents the ectotherm.
Learn the difference between endotherms and ectotherms, how they regulate their body temperature, and how they exchange heat with their environment. See graphs, examples, and key points of this ecology article.
Jan 28, 2020 · An ectotherm is an organism that gets heat from the environment, not from internal reactions. Learn how ectotherms regulate their temperature, why they have advantages and disadvantages, and see examples of ectotherms and endotherms.
Oct 19, 2023 · An ectotherm is an animal that relies on external heat sources to control its body temperature, which can fluctuate widely based on the animal’s surroundings. Learn about the benefits and disadvantages of being an ectotherm, and see examples of cold-blooded animals such as reptiles, fish and invertebrates.
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Mar 5, 2024 · Learn the difference between ectothermic (cold-blooded) and endothermic (warm-blooded) animals, how they regulate their body temperature, and what are the pros and cons of each strategy. See examples of ectothermic and endothermic animals, including some exceptions and adaptations.
Oct 31, 2023 · Ectotherm. An ectotherm, from the Greek (ektós) “outside” and (thermós) “hot,” is an organism in which internal physiological sources of heat are of relatively small or quite negligible importance in controlling body temperature. Since ectotherms rely on environmental heat sources, they can operate at economical metabolic rates.
