What is an Extremophile? - Lesson for Kids

Instructor: Suzanne Rose

Suzanne has taught all levels PK-graduate school and has a PhD in Instructional Systems Design. She currently teachers literacy courses to preservice and inservice teachers.

Do you hate going outside when it's too hot or cold? In this lesson, you'll learn about living things that can survive in many different environments in which people can't.

Conditions for Life

Every species of life on the Earth needs certain things to survive. Humans can only survive in certain environments. For example, we must have oxygen and fresh water, and we can only survive in certain temperatures.

Did you know that there are many living organisms that can survive in environments where people can't? These organisms are called extremophiles (pronounced EK-streem-uh-file). The suffix '-phile' means 'one who loves.' So, an extremophile is an organism that loves an extreme environment or in other words, one in which humans couldn't survive.

Over time, these organisms have developed so that they not only survive, but thrive in extreme places on Earth.

Kinds of Extremophiles

There are many different kinds of extremophiles. Let's look at some of them and find out where they live.


Any time you see 'therm' in a word, it tells you that the word has something to do with heat. Thermophiles, pronounced 'THER-muh-files', are organisms that live in areas where the temperatures are very, very high.

Pompeii Worm

These are mostly bacteria, which are very small, single-celled organisms. Scientists have found them living in places such as hot springs in Yellowstone National Park or hydrothermal vents on the ocean floor. One thermophile is the Pompeii worm, which lives in the Pacific Ocean near hydrothermal vents.


The opposite of thermophiles, psychrophiles (SY-kro-files) live in areas that are extremely cold. They are also called cryophiles. Scientists have found that some of these organisms have developed certain substances in their bodies that keep them from freezing.

For example, people who live in cold climates might put antifreeze into their car engines. Antifreeze is a liquid that moves through the engine and keeps it from freezing when the temperatures get very cold. Psychrophiles have a similar antifreeze substance in their bodies so that they can live in extremely cold environments.

Rocky Mountain Tailed Frog is a cryofile.

Some other psychrophiles, such as frogs like the Rocky Mountain Tailed Frog, can make themselves freeze very quickly when the temperature falls. This makes their body freeze without causing damage to it so when the temperatures warm up, they can thaw out and still be alive.

Other Extremophiles

Some other extremophiles include:

  • Halophiles (pronounced 'HAL-uh-files') can live in very salty areas.
  • Piezophile (pronounced 'PEE-zuh-files') can live in areas where there is a lot of pressure, such as at the bottom of the sea.
  • Endolithic (pronounced 'en-do-LITH-ik') creatures can live inside rocks or minerals.
  • Xerophiles (pronounced 'ZEER-oh-files') can live in very dry conditions with little water.

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