Archaea Lesson for Kids: Definition & Facts

Instructor: Lindsy Frazer

Dr. Frazer has taught several college level Science courses and has a master's degree in Human Biology and a PhD in Library and Information Science.

When you think about microscopic creatures, bacteria probably come to mind. But, bacteria aren't the only single-celled organisms around. Learn about Archaea - single-celled creatures that can be found in extreme places - in this lesson.

What Are Archaea?

Teeth. Skin. Intestines.

What do these things have in common? Of course they're all parts of your body, but they're also all home to microscope organisms called Archaea (pronounced AHR-kee-uh)! That's right, hanging out around your teeth, on your skin and in your intestines are teeny, tiny creatures! But have no fear - these little guys don't just call your body home - they help you out.

Archaea are single-celled organisms that often live in extreme places, like your guts! Like bacteria, Archaea are prokaryotic (pronounced proh-KAR-ee-oht-ik) cells: the smallest type of cell around. Because a prokaryotic cell is so small, it doesn't have a nucleus or organelles, structures that preform specific tasks in a cell. And while it might be scary to imagine microscopic organisms hanging out in your gut, these Archaea actually help you digest the food you eat.

Shape and Size

Archaea come in different shapes: rod, cone, square and round. They're anywhere from 0.1 to 15 micrometers in size: compare that to the average grain of salt, which is about 1,000 micrometers.

Archaea are single-celled prokaryotes.

Why Are Archaea Called Extremophiles?

Inside the human body isn't the only extreme place you'll find Archaea. Most Archaea are considered extremophiles (pronounced EX-stream-o-fahyls) because they live and thrive in extreme conditions.

Archaea can be found in places with extremely high and low temperatures, like deep sea thermal vents or the waters around Antarctica. They can also be found in very salty places like the Great Salt Lake in Utah, where the water can be up to 27% salt. You'll even find Archaea in very acidic environments. Talk about extreme!

Theromphiles and Psychrophiles

Scientists classify extremophiles like Archaea according to the type of extreme environments they call home. Archaea that live in very hot environments, like the hot springs in Yellowstone National Park where temperatures can reach 160 degrees Fahrenheit, are called theromphiles (pronounced THUR-muh-fahyls). Psychrophiles (pronounced SY-kroh-fahyls) are Archaea that live in extremely cold places like the polar seas. While they can live almost anywhere, the largest number of Archaea live in extremely cold environments.

Most Archaea live in extreme environments, like this hot spring where temperatures can reach 160 degrees Fahrenheit.

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