14 amazing facts about tardigrades, the world’s toughest animal

Tardigrades are hardy animals, capable of surviving almost anywhere – including space! They are also pretty remarkable creatures, helping us understand the finer points of quantum theory. Here are a few fascinating facts about one of the most alien animals on Earth:

Tardigrades are also known as water bears or moss piglets, but the actual word ‘tardigrade’ means ‘slow paced’. It was originally an adjective applied to tortoises, but since 1800 it has been the name of these microscopic creatures.

At only about 0.5mm long, tardigrades aren’t big, but they can be found around the world in a wide range of environments.

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Tardigrades eat bacteria, plants, or even other tardigrades. They pierce individual cells of their prey and suck out the contents for nutrients. Delicious!

Tardigrades can cope with extreme high and low temperatures that would kill other organisms. Some species can survive exposure to -272.15°C.

Tardigrades can also survive immense pressures, up to six times that on the ocean floor, or even being boiled in alcohol.

If a tardigrade is dehydrated and loses up to 99 per cent of its water content, its living processes can be near-suspended for several years before being brought back to life. In its dehydrated state, it is known as a ‘tun’. A tun’s metabolism lowers to as little as 0.01 per cent of its original rate.

A tun can be carried on the wind, like a seed or spore. If it lands in a habitable environment, it can asexually reproduce and start a new colony.

In 2007, dehydrated tardigrades were taken up into orbit and exposed to the vacuum and radiation of space for 10 days. On return to Earth, over two-thirds of them were successfully revived. Many died relatively soon after, but were still able to reproduce beforehand. Of course, this does not mean tardigrades are aliens.

Inside the cells of dehydrated tardigrades, a type of protein called ‘tardigrade-specific intrinsically disordered protein’ (TDP) replaces the water. This forms a glass-like substance that keeps the cell structures intact.

Yeast and bacteria can be protected from dehydration by encoding into them the tardigrade genes for producing TDPs. This method could be used to produce crops that can survive droughts or medication that doesn’t need refrigeration.

The hind pair of a tardigrade’s eight legs are attached backwards, and are used for grasping objects.

Tardigrades are among the few animals to have lived through all of our planet’s big five extinction events.

At this point it sounds unlikely but yes, tardigrades can die – they aren’t completely invincible. The remains of a dead tardigrade were found alongside crustaceans frozen a kilometre under the surface of an ancient Antarctic lake.

In April 2019, the Israeli lunar lander Beresheet crashed onto the Moon’s surface, thus bringing its mission to an abrupt end. But part of its cargo (alongside classic books, human blood samples and the entirety of Wikipedia) contained a colony of tardigrades, who scientists believe are extremely likely to have survived the impact.

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