Tiny, but not small. That’s the tardigrade in a nutshell. But there is so much more to say about it.

And we do that this weekend on the basis of nine facts with which you can effortlessly make the most of a birthday or at the coffee machine at work. Because tardigrades are really cool!

1. Small and can be found everywhere (also in the Netherlands!)

Tarsiers – also known as water bears – are very small, multicellular organisms. They can be up to half a millimeter long and have eight legs, with which they can walk and run. The bear animal does not exist; more than 1000 species of tardigrades are known! And they live in diverse environments; from mountain peaks to deep seas and from tropical rainforests to Antarctica. Bear animals are also found in the Netherlands. For example, they were found on the beaches along the Oosterschelde.

2. tardigrades are very old

About 66 million years ago, an asteroid hit Earth. It turned out to be the final nail in the coffin of the dinosaurs and numerous other species. It is perhaps the most famous mass extinction to hit the Earth. And however catastrophic the consequences were; the tardigrade survived this mass extinction. Just like the four(!) great mass extinctions before that, because scientists think that the tardigrade has existed on earth for about 540 million years.

3. The tardigrade will probably last a while

Although the tardigrades have been around for many years and have survived many catastrophes, many researchers believe that there is much more in store for the tiny critters. For example, a 2017 study suggested that really only the dying of the sun could lead to the extinction of the tough tardigrades. It would mean that tardigrades still have about 10 billion years ahead of them.

4. Cold is not a problem…

Where we start to complain a lot with a few degrees of frost, tardigrades don’t budge. In fact, you can freeze them for years and then when you thaw them, witness how they effortlessly pick up their lives again! Researchers discovered this about five years ago when they found tardigrades in Antarctic moss that had been frozen for research purposes 30 years earlier. They thawed two tardigrades and then saw how one of them successfully resumed its life, which had been stopped in 1983, and even laid eggs about six weeks after its thawing, which almost all hatched. An egg that was found in the moss also hatched after thawing – and therefore with a delay of about 30 years – and the tardigrade that hatched there also successfully reproduced.

A bear animal. Image: Schokraie E, Warnken U, Hotz-Wagenblatt A, Grohme MA, Hengherr S, et al. (2012) (via Wikimedia Commons).

5. …and neither does dangerous UV radiation

Tartars have already endured a lot in the name of science. For example, last year they were placed under a germicidal ultraviolet lamp. The aim was to find out how much UV radiation different types of tardigrades could have. Most tardigrades turned out to be quite tough. A dose that is fatal for bacteria and roundworms after just five minutes – most tardigrades only become fatal after 24 hours. And one of the species studied did not shrink at all, so the researchers decided to increase the dose of ultraviolet light four times. And this time too, the mysterious tardigrades didn’t give in easily. About sixty percent of these plucky tardigrades survived for at least a month after being damaged!

6. You can shoot them too

As if that experiment wasn’t intense enough, scientists – chasing the limits of the tardigrade – went a step further earlier this year. They put frozen tardigrades in a loaded gun and then fired them at high speed. The research found that tardigrades can survive impacts up to about 900 meters per second. “They are tough creatures,” concluded researcher Mark Butchell, who wanted to use the experiment to determine whether tardigrades that are flung together with rock at the moon during an impact on Earth, can tell that story. The experiments suggest that it is conceivable under certain circumstances. Whether they would then also be able to make the moon their home is very doubtful.

7. Or let it dry out

When we don’t drink for several days in a row, we become dehydrated. And that’s not good. The tardigrade is a lot less dependent on moisture; experiments show that the animal can live without water for up to ten years! Once they contain less than five percent of their normal water supply, they go into standby mode, making proteins along the way that turn parts of their bodies into a glass-like substance, protecting their cells from drying out. And if they do feel wet again? Then – even if they have waited years for water – they can come back to life in twenty minutes.

8. They’ve already been in space

Becoming an astronaut: who doesn’t dream of that? For some tardigrades, that dream has already become reality. In 2007, ESA launched a colorful collection of tardigrades into space. “Our most important discovery is that the vacuum in space – and associated dehydration – and cosmic rays were not a problem for tardigrades,” concluded researcher Ingemar Jönsson in 2008. The same was true of the extreme cold to which the tardigrades were exposed in space. . More experiments in space followed in the years that followed, each confirming that the tardigrade is generally unimpressed by the conditions prevailing there. It is still difficult for scientists to explain this, which is why tardigrades were sent to the International Space Station earlier this year. Experiments look at what happens to the genes of tardigrades when they are in space. Which genes are turned off or activated? And then what happens? Researchers hope to gain more insight into the tardigrade’s survival strategies, which could help future astronauts. For example, it could lead to new ways to better protect biological materials – such as food, but also medicines – against extreme temperatures, dehydration and cosmic radiation.

To the moon
It is already very impressive that the tiny creatures have traveled to the ISS and can make a major contribution there to future space missions. But there are tardigrades that have made it even further and have flown all the way to the moon. These tardigrades hitchhiked with lunar lander Beresheet in 2019. Unfortunately, the lander crashed on the lunar surface, but the tardigrades may have survived the crash. However, it is impossible that they will see the moon as we speak are colonizing; the lander contained desiccated tardigrades that can only become active again if they are exposed to significant amounts of water and are not available on the moon.

9. They lay huge turds (relatively speaking)

Tarants may look a lot like superheroes; in some ways they are just like us again. Sometimes they just have to poop. But the tardigrades wouldn’t be tardigrades if they didn’t steal the show in that area too. For example, research has shown that the tiny critters produce huge turds that are sometimes almost as big as themselves! And yes, there are pictures of that. Click!