Tuesday, January 26, 2010

Nature's Pole-vaulter

This engaging little animal is a springtail – a member of an ancient lineage of six-legged arthropods called the Collembola, that resemble insects but differ in having internal rather than external mouthparts. Springtails are everywhere and most live on detritus. This one, which was about half a millimetre long and just visible to the naked eye - and which I think belongs to a genus called Deuterosminthurus - was rambling over the surface of the soil in a flower pot in our conservatory. Lift up the lid of your compost bin and you’ll often see swarms of them scuttling around on the surface ........ and if you disturb them they leap into the air, using.......

... a specialised structure called a furcula attached to their tail and folded underneath the springtail. You can just see it in this photo, behind the set of legs closest to the camera, pointing towards the head. Springtails use their furcula much in the same way as a pole-vaulter uses their pole. It’s under permanent tension and when the animal releases it from the catch that holds it in place it flicks down instantaneously, catapaulting the animal into the air and away from danger. The tip of the furcula in this species is .....

forked – as you can see here, where it appears to be using it to scratch its mouth.

While I watched this particular animal gave itself a pedicure and rather remarkably you can see that it’s got all three legs on one side off the ground.... so why doesn’t it fall over? If your dog did that, lifting both legs on the same side, it would roll over.... but maybe if it had six-legs instead of four it wouldn't because.....

...... as you can see when the springtail tilted itself the other way and lifted all three left-hand legs off the ground, the right hand legs are acting like a tripod with feet evenly spaced at the points of a triangle.

There are numerous species of springtails that are fascinating to study, if you have a microscope. You can find a wonderful photoguide to many of the species in Britain here and you can see a wonderful movie, from David Attenborough's Life in the Undergrowth at http://www.youtube.com/watch?v=OwOL-MHcQ1w showing these pole-vaulters in action.


  1. Yes i am familiar with grubs, those in the composts are even as big as a thumb, am afraid of those, a bit yucky but i know they are friends. They are not as monstrous when the become beetles.

  2. Hi Andrea, most of the inhabitants in our garden compost tend to be small.....


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