If you’ve never heard of space bears, water bears or moss piglets, then you are not alone! Until this morning neither had I. I was looking at the various gradings of animals to choose which one to write about when I came upon ‘tardigrades’ – also known as space bears, water bears and moss piglets. You can see why from the image above. It looks like something you might see in an episode of Doctor Who – and given its unusual DNA, it could well be from outer space!
Tardigrades are capable of surviving the most extreme conditions, from absolute zero to boiling; from huge amounts of radiation to untold pressure on their bodies. They have been found high up mountains, deep in the oceans, in hot springs and, amazingly, in Antarctica (if you’ve been reading our Nature Matters blogs, you’ll know that even the most widespread animals steer clear of the harsh conditions of Antarctica). Even more impressive is that they can go without food or water for years.
Just like the pseudoscorpions I wrote about recently, tardigrades are ancient, with fossils dating from 530 million years ago. There are over 1,000 species of tardigrades – so why haven’t you ever seen one? Well, just like our fake scorpions, tardigrades are small… but much smaller than pseudoscorpions. They average a mere 0.5mm in length and live mainly on plants, moss, lichen and small invertebrates. They can be seen under a microscope, but you’d have your work cut out finding them in the first place! Your best bet is to soak a piece of moss in water and then view it under the microscope.
You might wonder why they are called space bears. Well, in addition to being one of the few species to have survived the five mass extinctions on Earth, they are also the first known animal to survive in space. In 2007, a number of dehydrated tardigrades were exposed to outer space’s hard vacuum for 10 days. When brought back to Earth, over 68% revived within half an hour after being rehydrated.
Given that we are able to study the micro-world more closely these days, who knows what we might discover in another few years. Perhaps the master race (who we assume to be us) is actually a miniscule survival machine, just like the tardigrade.