Thursday, 22 April 2010

Slough it

One advantage of taking one of those child things with you is that they spot the stuff you miss.  Their eyes are a) better b) closer to the ground and c) not troubled by the vagaries of varifocals. So it was that I walked straight past the lizard on the delapidated dry stone wall until my daughter's excited shout from behind pulled me up sharp.

The lizard shot into the undergrowth so we stood and stared until it came out again. It was only afterwards when we looked at the photographs that we realised that it was actually in the process of sloughing off its skin.  Reading up a bit on this, that the protective scales you see on a lizards body are actually underneath a top layer of transparent skin.  Common lizards regularly slough off (or should that be sluff ough?) this outer skin. It enables growth but full size adults also do it - apparently it assists in repair and parasite removal.  Good job humans can't do it or the anti-wrinkle cream industry would collapse.

You can see the skin pulling away from the body just behind the back legs in the photo above and also on the back foot..

The following day we were back in the same place and found a piece of the sloughed off skin.

This piece shows the larger-sized underbelly scales with smaller ones from the lizard's sides.  The picture below is taken down a 10x binocular microscope and shows the delicate structure.

The other interesting thing about this lizard was that it had lost its tail.  A stump with a black scar was all that was left. Its a handy defence mechanism if grabbed by the tail of course, but how does it work. The New Naturalist series volume on reptiles and amphibians explains that several of the tail vertebrae have central areas which never actually fully harden into bone.  These form planes of weakness at which the tail can break off.  (Autotomy is the posh word)  The bit that intrigued me most is that the lost tail wiggles and twitches for a while to distract the predator while the lizard beats a hasty retreat. People have found lizard tails in the crops of birds of prey and in the stomachs of carnivorous mammals so it must work.


  1. Well seen, and an interesting post - thanks.

  2. Well done the 'child thing', another great post, Linda

  3. Thanks Rob and Linda for the feedback. Will pass on your compliments to the small person, Linda.