SMALL & MIGHTY
An expert explains why tardigrades – a microscopic marvel nicknamed the water bear – is tougher than it may look
WHEN you think of nature’s most ferocious animals you think big – tiger, shark, crocodile or Komodo dragon maybe.
But creatures don’t come much tougher than the tiny tardigrade.
Nicknamed ‘water bears’ after their cute, bear-like walk and affinity to H2O, tardigrades can withstand extremes of heat and cold, the effects of radiation and even the vacuum of space, thanks to millions of years of evolution.
These eight-legged creatures are common – there will be some lumbering about your garden right now – but you won’t be able to spot them as they can only be seen under a microscope.
The largest tardigrade species can grow to a little longer than 1mm in length but most are smaller than the full stop at the end of this sentence.
Tardigrades need moisture – at least a thin layer of water around them – to survive. You can find them in ponds and puddles, on moss and in soil.
Jasmine A Nirody, Independent Research Fellow at All Souls College, University of Oxford studies these microscopic marvels.
She says: “Tardigrades are super tough and they’ve been shown to live through a lot of seemingly impossible hardships. Maybe the most impressive is that they can actually survive in the vacuum of space, at least for a little bit of time!
“There are some tardigrades that can survive past the boiling point of water and there are species of tardigrades that live in Antarctica so a little ice doesn’t hurt them. But even the toughest tardigrades have weak spots and there’s none that are totally indestructible.”
These little creatures are big eaters…
“Most tardigrades use needle-like parts in their mouths to poke holes and suck the fluid out of cells in the algae, plants and fungi around them,” says Jasmine. “Other tardigrades eat whole animals: nematodes, rotifers and even other tardigrades.”
The oldest fossil of a tardigrade is about 90 million years old but scientists only discovered them in the late 1700s after the invention of the microscope.
Jasmine says there is still plenty to learn about them. “There are over 1,000 known species of tardigrades and we’ve only studied a couple in detail.
“They live in a huge range of different environments but, despite this, tardigrade species all look the same.
“Their body structure hasn’t changed much in almost a 100 million years. I’m really interested in how they are able to survive and move around in so many different places.”
■ For more information, including a video of a tardigrade walking, see ox.ac.uk/news/features/ physics-behind-waterbears-lumbering-gait