What is the most indestructible animal you can think of? Has it been frozen, or sent into outer space’s vacuum and radiation, or dried out for eight years, survived all five mass extinction events, or boiled? And, after all that, has come back to life and successfully reproduced? I’ll tell you what can – cooties. Water bears. Moss piglets. Otherwise known as tardigrades.
If a tardigrade was an Exetah student, it would cycle up Forum Hill all the way to the Sports Park, do a pole fitness class, write its dissertation then do a record bolt time, all without busting a sweat. This is the ultimate animal. Though admittedly quite tiny, so you’ve probably never seen one unless you have a microscope handy. Being between 0.5 and 1.5mm long, makes it one mean microanimal.
The tardigrade’s extreme tolerance is mainly thanks to the fact it can reduce its metabolism to 0.01 per cent of what it is usually, losing nearly all body water to become a frozen-in-time version of itself: a tun. DNA damage that occurs during this state is somehow fixed. They can even survive pressures of 600MPa, which is six times the pressure you’ll find anywhere on Earth, even in the deepest ocean trench.
So why do they bother being superheroes if they’re not gonna take over the Earth? The word tardigrade derives from the Latin for slow walker, and this is accurately descriptive.
Most species are quite happy with a nice bit of moss to call home, occasionally using their piercing claws and teeth to prey on each other. Or to just drink algae and float around in the sea. Not particularly impressive. But, their amazing abilities mean they kind of have taken over the Earth – they’re found in habitats so inhospitable that few other animals can survive. It’s all a case of competition and exploitation. Tardigrades are generally winning at life.
The fabulous thing about tardigrades is that we don’t really understand them. What the exact protectants are that allow them to stay alive – even in their tun state – is unknown. How do they even fix DNA mutilation which occurs in such damaging conditions? Though they’ve been in existence for over 500 million years old, tardigrades aren’t giving up all their secrets just yet.