Tardigrade (Water Bears)

Tardigrade (Water Bears) / Schokraie E, Warnken U, Hotz-Wagenblatt A, Grohme MA, Hengherr S, et al. (2012) / Wikimedia / CC BY 2.5

The tardigrade is the most amazing little creature you’ve never heard of

Moss piglet. Water bear. Picture a creature that fits those names and just try not to smile. The tardigrade might not be as popular as baby panda bears or as easily photographed as piglets wearing rain boots, but they are just as deserving of our attention and our love.

Not only are tardigrades super adorable (if you can get a good picture of them), but they may hold the secret to our survival.

What is a tardigrade?

A tardigrade is more than just an animal, it is an entire phylum. Remember back to your biology days? All animals are classified by phylum, class, order, and family. Tardigrade is a phylum just like Chordata (like pigs and people) and Arthropod (insects). There are over 1,000 different identified types of tardigrade, and while some are hardier than others, they’re all exceptional.

To be considered a tardigrade, a little creature has to check a bunch of boxes. You’re cool too, but sorry, you probably don’t qualify.

First off, tardigrades are tiny. Like really, really tiny: they usually measure between 0.005 millimeters and 1.2 millimeters (0.002 inches to 0.05 inches) long. That’s about twice the size of an average pebble. You can see them with a powerful magnifying glass, but not with your eyes alone.

Underside of a TardigradeUnderside of a Tardigrade
Underside of a Tardigrade / Willow Gabriel, Goldstein Lab / Wikimedia Commons / CC BY 2.5

A closer look

If you’re ever lucky enough to get up close and personal with a tardigrade, you’ll discover some pretty unique physical features, too. Their bodies are long and covered in thick fat rolls, but they’re not all roly-poly and friendly.

These creatures also have flat faces…usually. Their little mouths pop out when they need to eat or explore. And because they’re often transparent, you can examine their most recent meals with ease, assuming you want to know.

Don’t make fun of a tardigrade for being fat or funny-looking. Each of their eight legs ends with between four and eight claws, so if you stumble upon them (and happen to be about 0.01 inches long), you might be in for a dangerous encounter.

Tardigrades don’t just survive with their wits and their claws. The magic of a tardigrade is far more impressive than that. 

Who discovered tardigrades?

Tardigrades are tiny, right, so it’s not like a scientist stumbled upon an ancient tardigrade skeleton or discovered a secret colony in the vast recesses of the rainforest. And just like there’s more than meets the eye with the tardigrade itself, its origin of discovery story is pretty cool, too.

Johann August Ephraim Goeze was the first person to ever see, recognize, and name a tardigrade. In 1773, Goeze noticed these microscopic little creatures ambling around in water (one of their favorite habitats).

He named them “kleiner wasserbär,” which means “little water bear” for their movement style, which is strikingly similar to their exponentially larger bear namesakes.

A couple of years later, in 1777, Lazzaro Spallanzani (who had more than just an incredible name) coined the term “tardigradium,” which became the official name for the phylum Goeze discovered.

…There are tardigrades everywhere. Literally. 

And while it’s amazing that a zoologist in the late 18th century would discover such tiny little beings, it might be even more incredible that no one had ever discovered them before. Not only was the microscope was invented in 1590, but also there are tardigrades everywhere. Literally.

What makes the tardigrade so incredible?

When you first skim through a list of the tardigrades’ favorite homes, it feels pretty standard and unimaginative: they can live in water, they can live on moss, they can live in the cold, and they can live in the heat. But the further you delve into the living habitats of tardigrades, the more amazing they seem.

Tardigrades can live anywhere. Read that sentence again: tardigrades can live anywhere. They can survive extreme temperatures, crazy variations in air quality and chemical makeup, and countless disasters that would (and have) completely destroy anything and everything else on this planet.

They can survive in boiling water without blinking, radiation doesn’t seem to impact them, and they can hang under pressure.


You can’t survive in an environment that is negative 328 degrees Fahrenheit (negative 200 Celcius), but a tardigrade can. However, unlike a lot of cold-weather friends, tardigrades can also deal with extreme heat: 300 degrees Fahrenheit (148.9 degrees Celsius) is about their max.

But that’s not all. They can survive in boiling water without blinking, radiation doesn’t seem to impact them, and they can hang under pressure. Even when they’ve been put in environments with over six times the pressure of the deepest oceans, they’ve been fine.

The list keeps going. While tardigrades do just fine in our world (they live in the rainforests, in volcanoes, and even in Antarctica), they can live happily and relatively healthily even in space with no atmosphere at all.

The earliest tardigrade population was probably hanging out on Earth around 530 million years ago.

Based on tardigrade fossil records, they’ve certainly been around much longer than we have.

How do tardigrades do it?

The secret to tardigrade success isn’t all that secret, as it turns out. Spallanzani (of cool name fame) uncovered their little mystery back in the 18th century, but thanks to genome sequencing, we’re learning more and more about the tardigrade and its indestructibility all the time.

Spallanzani first discovered that tardigrades are able to survive in extreme environments by witnessing the little animals actually transform when introduced to new situations. Depending on the atmosphere, temperature, and other elements, tardigrades have a variety of survival skills up their fat little sleeves.

The tardigrades’ first impulse when faced with disaster, cold, or heat is to curl up in a ball and nearly die — they’re not unlike people in this way.

However, for tardigrades, it’s pretty successful: when they curl up, they’re able to dehydrate their bodies and remain perfectly preserved and healthy until they are reintroduced to water. Then they plump back up, happy and ready to face the day.

How are they different?

Tardigrades’ bodies produce a series of different gels, antioxidants, and proteins that protect their organs and DNA from damage.

But just because the tardigrades can dehydrate and rehydrate more or less at will to avoid their biggest problems doesn’t mean you can. Their little bodies produce a series of different gels, antioxidants, and proteins that protect their organs and DNA from damage when they’re in their dehydrated state (called cryptobiosis).

These elements also protect their bodies from things like radiation, so they’re all set.

Scientists in Japan were so interested in the incredible powers of the tardigrade that in 2016, they sequenced its genome.

While much of the information they found lined up with what we already knew about their survival skills (they isolated the radiation-protecting proteins, for example), they discovered even more information that is directly applicable to our human world.

DIY tardigrade discovery

Still not convinced that tardigrades are oh-so-amazing? Check one out for yourself.

Follow these easy steps to find, meet, and care for tardigrades in your neighborhood.

  • Get a piece of old moss from the base of an old tree
  • Soak the moss in water overnight (or for at least a couple of hours)
  • Using a dropper, put a couple of droplets of water on a slide
  • Cover the water with a slide cover
  • Look at your water with a microscope

You should be able to see your new friends with even a low-powered microscope or a magnifying glass. After you meet your new tardigrade pets, consider this: these little guys might someday save your life.

Why should we care about tardigrades?

First off, tardigrades are a part of our ecosystem and our world. Who knows what benefits they may be silently and secretly providing us? But selfishly, they might also hold the secrets to our long-term success.

After the genome-mapping team isolated the radiation-blocking protein found in tardigrades, they decided to take it to the next level: people.

When they added this particular protein to human DNA, they discovered that the protein reduced the harm done to human DNA by x-rays by 40 percent. That one little protein had amazing power and potential to protect.

Imagine what else tardigrades might have to teach us.

The tardigrades’ ability to live in heat and cold without an atmosphere and with a great deal of pressure, and in situations of starvation and deprivation, might teach us valuable lessons about how to thrive in our ever-changing world.

A deeper dive — Related reading from the 101:

Just like this list of animals, tardigrades aren’t big, but they are powerful. Sometimes the most incredible animals come in the smallest packages!

Tardigrades might make space living sound cool, but once you read about the status of the space station, you might be second-guessing your dreams of traversing the universe. 

Don’t worry, it’s not going to hit us! But even if it did, tardigrades would be totally fine.