Ectotherms: Definition & Examples

Lesson Transcript
Instructor: Elizabeth Friedl

Elizabeth, a Licensed Massage Therapist, has a Master's in Zoology from North Carolina State, one in GIS from Florida State University, and a Bachelor's in Biology from Eastern Michigan University. She has taught college level Physical Science and Biology.

Most organisms thrive at an optimal body temperature. In this lesson, you will learn about how some animals rely on external sources to raise or lower their body temperature because they are not able to maintain it through internal processes.

What Are Ectotherms?

When you get cold, you probably warm up by putting on some extra layers or going to a warmer place, such as the inside of a building. Changing your environment helps warm you up, but your body is also at work because it stays pretty much the same temperature no matter what the temperature is around you.

Your body regulates its own temperature because your cellular functions and processes work the best when you are approximately 98.6 ° F. Because your body is able to maintain a specific temperature despite the surrounding conditions, you are an endotherm.

There are many organisms that are not able to maintain their own body temperature, and these are called ectotherms. Ectotherms depend on the external environment to either warm or cool themselves because their body does not do this for them. Like your body though, the cellular processes of ectotherms also function best at certain temperatures, so ectotherms find various ways to make sure they do not get too hot or too cold.

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  • 0:01 What Are Ectotherms?
  • 1:00 Examples
  • 2:12 Depending on the Environement
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One way that ectotherms may increase their body temperature is to seek out heat sources. Reptiles are a great example of this. Snakes, turtles, lizards, and alligators are all examples of animals that use the sun to warm themselves. You may have even seen this, as many of these animals lie on hot pavement during the day or come out of the water to bask on logs or small islands. Likewise, if they get too warm, they may seek out shade to cool off.

An alligator sunning itself for warmth

Some ectotherms regulate their body temperature by living in environments that have fairly constant conditions. Many marine invertebrates live in aquatic conditions that fluctuate very little, and therefore do not need to seek out heat or cooling sources because their body temperature matches that of the surrounding water.

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