Tardigrades

Episode 3 – Tardigrades: The Teeny Titans Living in Your Backyard

Superheroes are great. They save the day, beat the bad guy, and rake in ticket sales at the box office. But what if one of those heroes could leap off the silver screen and right into your electron microscope? That’s right, we’re talking about the tardigrade–nature’s indestructible little potato worm. But what is a tardigrade? Why is it a superhero? And why should I care?

All valid questions.

Let’s put on our sciencing caps and take a deep dive into the semi-microscopic world of the teeny tiny titan tardigrade to see just how resilient this little sucker is.

Tardigrade Taxonomy

But first, some taxonomy. (This is Life, Death, and Taxonomy after all).

Kingdom: Animalia

Phylum: Tardigrada

And that’s it. Tardigrades aren’t just a single species of animal, they’re a whole phylum made up of over 1,100 species!

Basic Tardigrade Info

Now that all that classification is done, let’s talk about some general info concerning our new friend, the tardigrade.

In case you can’t see or don’t want to look at the image above because it’s too offputting, we’ll explain the tardigrade’s basic appearance. Imagine a fat caterpillar with well-defined legs, adorable little feet, and a tubular mouth for a face.

For the most part, these guys are clear or a pinkish color, but it’s tough to tell due to their pathetically small size. Although their color can often change based on what is in their stomach. They use their eight legs to lumber and dog paddle around the universe depending if they’re on land or in the water, which is why the Germans call it a “Wasserbären” or water bear and millennials call it a “space bear”. They’re also known as “moss piglets”, which is way more adorable than these lumbering flesh bugs deserve. The name “tardigrada” actually means “slow stepper”, so despite having telescopic legs, they still can’t get around very quickly.

Their bodies have a substance that arthropods in prestigious circles like to call chitin, which is in turn covered in hair-like bristles. They can “see”, so to speak, but not like we humans can. Tardigrades sport little eye holes that let in light and tell them whether something is bright or whether it isn’t–that’s about it.

Range

Due to characteristics that we’ll go over later, the tardigrade is thoroughly capable of living just about anywhere on the Earth below and sky above. They can be found on every continent including Antarctica and it any environment that could possibly be described as wet.

Habitat

These guys love water and general wetness. They can be found in oceans, seas, beaches, lakes, streams, creeks, rivers, ponds, and other bodies of water we can’t think of right now. They are also often found in moist mosses and lichens, which is gross but also convenient for studying.

Diet

Most tardigrades have weird tube mouths that they use to poke inside cells, invertebrates, and also algae to get the apparently delicious nutrients inside. So they spend their days stumbling around the world half-blind and when they bump into something tasty, they stab it with their tube mouths and suck out the good stuff.

Measure Up: How Big is a Tardigrade?

They’re tiny, possibly even teenily so. They’re not completely microscopic (your naked eye could pick up a particularly hefty specimen if it waved at you), but that doesn’t mean they’re easy to spot.

Here are the tardigrade facts:

Tardigrades range from 0.1 to 1.5 mm long. While that seems like not much of a difference, that’s a really wide range! It would be like crocodiles ranging from 10 to 150 feet long!

Fun Tardigrade Facts

Tardigrades are hardy folk. As we’ve mentioned, they can be found almost anywhere on Earth–and we mean anywhere. From the Arctic to the Himalayas to the Sahara to the Mariana Trench, moss piglets are there to be found.

We’re about to go over some crazy facts about how they can survive, but it definitely begs the question: how can they survive? Well, the tardigrade is capable of rolling itself into a little dehydrated ball called a tun. It can basically hang on to some water and dream of better days when the going gets rough. Its metabolism is completely suspended in a state called cryptobiosis, something science fiction nerds have only ever dreamed of. Depending on the type of harsh environment they’re facing, tardigrades will curl up into a tun using a different kind of osis:

  • No water: Anhydrobiosis
  • Extreme cold: Cryobiosis
  • No oxygen: Anoxybiosis
  • Toxic environment: Chemobiosis

They Can Survive Extreme Temperatures

Here are some mind-blowing stats on their resilience to extreme temperatures:

  • The can survive for several minutes at 304 degrees Fahrenheit (or 151 degrees Celcius), far above water’s boiling point.
  • If it’s a balmy -4 degrees Fahrenheit (or -20 degrees Celcius), they can survive for up to 30 years!
  • -325 degrees Fahrenheit (-200 degrees Celcius) puts their survival time at several days
  • And at an all-time low, tardigrades can survive for a few minutes at -458 degrees Fahrenheit, which is -272 degrees Celcius or 1 Kelvin! Remember, 0 Kelvin is absolute zero, meaning no molecular movement at all–no heat.

They’re Great Under Pressure

They can endure everything from a complete lack of pressure (the vacuum of space or a hacky sack game with some close friends) to incredibly high pressure scenarios (the bottom of the Pacific Ocean or deciding whether or not you can eat that last yogurt that expired yesterday).

They’ve even been recorded to endure over 6,000 atmospheric pressures, which is almost six times greater than the water pressure at the bottom of the deepest ocean.

They Don’t Need No Water

Thanks to anhyrobiosis, tardigrades can almost entirely dehydrate themselves and stay that way for nearly 10 years. They even found some promising leg-twitching in a tardigrade that dehydrated itself over 120 years ago! Now that’s an old moss piglet.

They Can Survive Severe Radiation

Radiation kills, remember that kids, except for the radiation that doesn’t. One of the main problems with outer space (and we’ll talk more about how lovely space is in a bit) is the fact that there is no atmosphere to shield you from a good healthy blast of solar radiation. Infrared, ultraviolet, gamma, and everything in between is flying at you at the speed of light, literally. And it’s enough to cook the insides of every living thing on the planet if it weren’t for the hundreds of miles of atmosphere we have.

But the tardigrade is different. It scoffs at us weak mortals as it flails helplessly in our test tubes. One study found that they can survive up to 6,200 grays of gamma radiation, which is a lot more than we can survive, which is about 10 grays.

But the real question is…

Can They Live In Space?

Of course they can! That’s why you clicked on this, isn’t it?

Space is a soulless vacuum of nothing that oscillates regularly from unimaginably hot temperatures to pretty close to absolute 0. Not to mention the unbridled stellar irradiation and complete lack of pressure that will suck the air right out of your lungs. Any living thing that is unfortunate enough to find itself exposed to pure space will freeze, boil, and suffocate to death in less than a minute.

But not the tardigrade.

A team of learned sadists that call themselves scientists exposed a petri dish full of tardigrades to space for 10 full days, of which, 68% survived after being rehydrated back on good ‘ol mother Earth.

You might be asking, “Hey, I thought these guys were cool with space and stuff. How come they didn’t all make it?”

Well, the answer is that tardigrades are not extremophiles, meaning that, even though they can take it, they don’t really get jazzed about the idea of being on the surface of the sun or at the bottom of the ocean or stuck in a glacier.

Also, a 68% survival rate after spending 10 unprotected days in space is a lot better than a congress of chimpanzees would do. They’re adapted to endure extreme conditions, not love them. Essentially, the longer tardigrades are exposed to space, the more they tend to die. Give the tardigrade a break!

So because they can survive extreme heat, extreme cold, high levels of radiation, zero pressure, and a complete lack of water and oxygen, the tardigrade is the only living thing that can tough it out in outer space.

That being said, you can still easily squish one with your finger–they’re very easy to squish.