Posted by: Ross Gardner | February 15, 2016

Back garden bear hunt

There are amazing things to be found in a back garden.  Come to think of it, there are amazing things to be found on a back wall or roof, if you don’t happen to live somewhere with a garden.  There is, in fact, much in the way of little-big game to be hunted down…… humanely.

The one catch is that you would need access to a microscope to be able to see it.  If that small problem is solved then the damp mossy corners, the lichen encrusting the walls and even either which might find a home on the roof-tiles, all come to life.  Collect some pieces of moss or lichen, soak them in distilled or bottled water for a minimum of two hours (preferably longer), draw up some of the water into a pipette, carefully squeeze a drop or two onto a microscope slide and get searching.

I did just this the other day – I’m not sure why I hadn’t done so before.  It was engrossing and fascinating.  I was motivated by the possibility of finding waterbears, or tardigrades.  These amazing little creatures are able to live more or less anywhere, provided they at least have a film of water to move about in, such as exists on damp clumps of moss and the like.  Most of them are less than a millimetre long and are truly microscopic.  They are also one of the most remarkable creatures on the planet.  When they become environmentally stressed they are able to completely dehydrate into a shrivelled ball (known as a tun) and reduce their metabolism to less than 0.01% of its normal rate.  In this crypotbiotic state they are able to tolerate astonishingly extreme conditions.  They have survived freezing to near absolute zero and temperatures well above boiling point.  They can withstand the extreme pressure of the deep, deep ocean and have been found six thousand metres above sea-level in some the Himalaya’s loftiest peaks.  They can tolerate levels of radiation a thousand times greater than would kill a human and have even survived full exposure to the vacuum of a space.  They would therefore be easy to find in my garden.

Well, no not really.  Things didn’t go quite as I hoped.  Not that that was too much of a problem.  I was quite staggered at the amount of lives being lived in just a few square centimetres of moss.  There were rotifers, tiny animals that feed by means of rings of bristling hairs (cilia) that drag food particles in towards their mouths.  These constantly moving cilia create the illusion of a spinning wheel, hence their name – wheel animals (rotifera is Latin for ‘wheel-bearer).  There were planarian worms gliding across the lens, nematode worms lashing around among the detritus and any number of exceedingly minuscule protozoans and algae.

I did find my waterbears after several hours of searching.  It was time though, well spent.  Until you’ve seen one you would not think it possible for a microscopic creature to look cute, but this is something that they definitely achieve, with their eight chubby legs and little snouted ‘face’.  I don’t have the facility for microscopic photography, so it’s down to good old Wikipedia to help out.

Waterbears imaged with a scanning electron microscope (from Wikipedia)

Waterbears imaged with a scanning electron microscope (from Wikipedia)

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