That’s life . . . but not as we know it

In the latest in a series of Friday science features we take a look under the microscope with microbiology expert Dr Paul Humphreys, senior lecturer in microbiology at Oldham’s degree partner, the University of Huddersfield.

Little monsters under the microscope

Ever seen a water bear or a moss piglet? I spent most of last week helping an artist find one of these animals, also known as a tardigrade.

Up to this point I knew very little about this unique group of animals, but in the interest of furthering art/science relationships I thought I would give it a go.

After all, how difficult could it be to find something with four pairs of legs, a fearsome collection of claws, two razor-sharp fangs and body armour?

The first thing I found out about tardigrades was that they were not as easy to find as others would have you believe. It took me quite a few hours to track down my first tardigrade, but I managed it in the woods behind my house.

Now, before anyone gets too worried, I should point out that tardigrades rarely reach a millimetre in length and most, but not all, are vegetarian.

In fact my first problem in finding one was looking for something that was much bigger than it actually was.

The specimens I tracked down were around a tenth of a millimetre long and completely see-through. I found them by soaking moss in rainwater overnight and gently squeezing out a water sample to view under the microscope.

So what’s the big deal with tardigrades? Well, alongside the fact that they look great, there are some very good reasons to study tardigrades.

Although very small, tardigrades share a lot of characteristics with other larger animals.

This, combined with some unique features, makes them a very interesting and useful research subject.

Tardigrades have been found in a wide range of environments from deep oceans to mountain tops and below ice sheets.

In order to survive in these environments, tardigrades have evolved the ability to deal with extreme environmental conditions.

They survive these conditions by transforming into a dormant state know as a “tun”.

When fully active tardigrades are as sensitive to environmental change as any animal, but when in its tun a Tardigrade is highly resilient.

In this tun state, tardigrades appear to be dead.

They don’t move, eat or have any detectable metabolism.

The ability to become so dormant that you appear to be dead is impressive enough.

But in the case of tardigrades, the tun state provides the organism with some quite amazing abilities.

Tardigrade tuns are able to withstand a thousand times more radiation than a human, thanks to some remarkable DNA repair mechanisms.

They can also survive extremes of pressure and exposure to a vacuum, as well as temperatures up to 150C and down to almost absolute zero.

They can survive all these extreme conditions and be revived as if nothing has happened.

The ultimate test of tardigrade resilience was when they were shot into space attached to a satellite.

Once in low earth orbit some were exposed to cosmic radiation, others to full solar radiation and all were exposed to the cold vacuum of space.

On their return to earth those exposed to cosmic radiation revived and reproduced as if nothing had happened.

Those exposed to the more aggressive solar radiation were less fortunate, but the fact that a few survived was remarkable.

So, the next time you are cleaning out your guttering, removing moss from the garage roof or simply walking the dog through the woods, you might like to reflect on the fact that you may be surrounded by some of the most remarkable organisms on the planet.

Alternatively, you may simply be happy to know that you really do have bears in your back garden.