Sciency Words: Tardigrade

Today’s post is part of a special series here on Planet Pailly called Sciency Words. Each week, we take a closer look at an interesting science or science-related term to help us expand our scientific vocabularies together. Today’s term is:


Tardigrades, a.k.a. water bears… there’s just something lovable about them. They’re kind of cute for microorganisms (or kind of horrifying, depending on which picture you’re looking at). And they’re absurdly tough. They can survive almost anything. They can even survive in space.

There have been several experiments now where tardigrades were taken to low Earth orbit and exposed to the vacuum of space for prolonged periods of time. Most of them survived the experience. In the absence of food, water, or oxygen, tardigrades can enter a state of suspended animation, and their cells have the ability to repair their D.N.A. if it gets damaged by solar or cosmic radiation.

In fact tardigrades seem to be so well adapted to the hazards of space that it’s sometimes suggested (usually not by serious scientists) that these little guys might come from space.

German pastor and zoologist Johann August Ephraim Goeze is credited with discovering tardigrades in 1773. Goeze called them Kleiner Wasserbär, which is German for “little water bear,” because the way they walk on their eight pudgy, little legs reminded Goeze of the plodding movements of bears.

In 1777, Italian biologist/Catholic priest Lozzaro Spallanzani made further observations of these creatures. Spallanzani called them il Tardigrado, meaning “slow walker,” again because of the slow, plodding manner in which they walk. The English words tardy and tardiness are closely related, etymologically speaking.

Today we’ve retained both tardigrade and water bear as common names for these creatures. Apparently some people also call them moss piglets, which is just adorable. Over a thousand species of tardigrade have been identified, all classified under the phylum Tardigrada.

As for the question about where tardigrades came from—are they native to this planet, or did they immigrate to Earth from someplace else?—I can only say this: if tardigrades do have an extraterrestrial origin, they must have arrived on Earth a very, very long time ago. The oldest known tardigrade fossils date back to over 500 million years ago (meaning they may have been here since the Cambrian explosion).

4 thoughts on “Sciency Words: Tardigrade

  1. Tardigrades may end up being the last form of complex life on Earth. As the sun heats up over the next billion or so years, Earth will gradually become less inhabitable. Tardigrades, or other organisms engineered based on their physiology, may be the last hardy souls. (At least aside from single celled organisms, who will probably be the very last living things, last as they were first.)

    Liked by 2 people

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.