Let’s learn about tardigrades

Tardigrades — also known as water bears or moss piglets — are pretty adorable. Under a microscope, each one looks a bit like a plump caterpillar, wriggling around on eight legs tipped with dainty clawed feet. But don’t let their cuteness fool you. These salt grain–sized animals are some of the toughest beasts on Earth.

Water bears can brave days in space without air. They can cope with temperatures colder than any ever measured on Earth. They have been known to survive hundreds of times the X-ray radiation that would kill a human. And they’ve even withstood getting blasted out of a gun at more than 1,800 miles per hour. Basically, tardigrades are the ultimate extremophiles.

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Why did these wee creatures evolve to be so durable? Some 1,300 species of tardigrades have been found. They thrive in ponds, streams and damp soil and clumps of moss. Many of those places can dry out in the summer. So tardigrades need ways to survive being parched. Adaptations they evolved to survive dehydration may have bestowed tardigrades with the power to survive other harsh conditions.

For instance, water bears make a special protein that could shield their DNA from damage when their cells get dehydrated. This protein may also protect their DNA from radiation damage. Similarly, water bears make proteins that act like tiny packing peanuts to keep their cells from collapsing as they dry out. Those same proteins might help the critters’ cells hold up against a deep freeze.

Learning what makes tardigrades so hardy could help people. For instance, these discoveries could lead to new ways to help cancer patients cope with radiation therapy. It might also offer clues about how astronauts — and crops — could survive long trips in outer space. 

Want to know more? We’ve got some stories to get you started:

Living mysteries: Why teeny-weeny tardigrades are tough as nails Tardigrades can somehow survive 500 times as much radiation as would kill a human. (1/27/2022) Readability: 7.0

Tardigrades survive harsh conditions by almost dying. Here’s how Under stress, chemical changes signal these water bears to enter a dormant state. (4/3/2024) Readability: 7.4 

A tiny microbe inspired this scientist’s big dreams Marc Mapalo looks at fossils to understand how tardigrades, or water bears, have changed over time. (9/19/2022) Readability: 6.9

Watch a brood of baby tardigrades hatch from eggs and start to explore the world. 

Explore more

Scientists Say: Extremophile

Scientists Say: Species

Scientists Say: X-ray

Scientists Say: Adaptation

Scientists Say: Protein

Scientists Say: DNA

This tiny animal is apocalypse-proof

Phoenixes aren’t the only creatures to survive the flames

A tardigrade protein helped reduce radiation damage in mice (from Science News)

Near-invincible tardigrades may see only in black and white (from Science News)

Glowing blue helps shield this tardigrade from harmful ultraviolet light (from Science News)

Activities

Word find

Where there’s moss, there’s likely moss piglets. That means the odds of finding tardigrades in potted plants, sidewalk cracks and other environments near your own home is pretty good. Learn more about how you can use household materials to find tardigrades and view them under a microscope in this YouTube video.