Tardigrades: meet these fascinating tiny water bears that are the toughest creatures on earth, able to survive being microwaved and sent to space

Tardigrades are probably among the most unbreakable creatures on Earth, able to survive dehydration, microwaving and temperatures as hot as 150ºC or as low as –273ºC.

They can also cope with being exposed to the ionising radiation of outer-space. Not tough enough? On top of all of these credentials, they can exist in suspended animation for over three decades. It is also claimed that these animals have the physiological capabilities to be the last beast standing in the event of a nuclear holocaust.

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What are tardigrades?

Tardigrades, which translates as ‘slow walkers’, are an eight-legged segmented micro-animal found from the deepest ocean sediments to the top of Mount Everest. But, luckily for you, they live in less exotic and more user-friendly locations too. That clump of moss on your garden wall or in your blocked gutter, for instance.

Why are they called water bears?

Tardigrades are also known as ‘water bears’ and ‘moss piglets’. Neither is a name that you would associate with such tough nuts, though these monikers go some way to describing the animals’ bumbling gait and chubby, turgid appearance. They’re clearly not mammals, however. Indeed, they are so weird and unlike any other life-forms that the 1,100 or so species have earned themselves a phylum all of their own: Tardigrada.

To put this in context: humans, real bears and actual pigs belong to the phylum Chordata, which includes all animals with backbones. In short, there is nothing quite like tardigrades – they’re unique. If you’re wondering why you’ve never bumped into one, it’s because they require a bit of looking for.

How big are tardigrades?

Even a large tardigrade is just 1mm in length, hardly colossal, so is easily missed. But tardigrades are as fascinating as they are small, and worth the extra effort to try to find – they’re probably among the few microscopic creatures that could be described as cute.

What do tardigrades look like?

That quilted, segmented, transparent body is equipped with four pairs of fleshy legs, each of which ends in a set of retractable claws (4–8 depending on species). These are used to swim or grapple their way through water and over damp surfaces. Their ‘face’ sometimes has a basic eye-spot on each side, but centrally positioned is the feeding tube through which the animals hoover up bacteria and algae.

How to find and see tardigrades

Intrigued? Want to meet one? Well, going on a bear hunt is really easy but you do need some form of magnification. While some large specimens can just about be seen with a hand lens, a microscope that can achieve around x15–x30 magnification is best, and x100 is even better.

All you need to do is scrape up a small quantity of soggy autumn leaves, a clump of moss or a fragment of lichen and then soak it. This is necessary to increase your chances of finding one, since any in their tun stage will have had time to rehydrate and become mobile. Now wring the material out, squeezing between your fingers, and collect the liquid. Next place a few drops at a time in a small, clear-sided pot, such as a petri dish.

Search through this liquid using a bright light or lamp shone from the sides. When you finally clamp your eyes on a dumpy creature complete with eight curious grasping limbs, you know you’ve found your tardigrade. It’s an animal everyone should meet at least once in their lives.