Lichen Spiders (Pandercetes gracilis) blend superbly with the surface characteristics of their tree. They remain strategically hidden from predatory birds and simultaneously well-positioned to ambush unsuspecting insects. Poorly disguised individuals are readily picked-off and the gene pool is progressively refined.
The close-up image (above) shows the orientation of the eight eyes; four looking down the surface of the tree, two looking back up the tree and two looking outward.
I do wonder to what extent individuals are capable of modifying their appearance to suit the tree? Likewise, to what extent are trees of suitable character chosen for their conformity with the appearance of the spider? I do know that egg-sacs are disguised by the spider through the deployment of silk of different colours, but what of the spider itself?
In the image below, a collection of lichen spiders shows an array of varied colours and patterns that suit a diversity of bark types.
Jennifer Marohasy BSc PhD has worked in industry and government. She is currently researching a novel technique for long-range weather forecasting funded by the B. Macfie Family Foundation.
Jennifer says
October 19, 2007 at 9:41 amThe first of the seven images is hauntingly beautiful!
As a collection they are intriging.
We should perhaps have a ‘blog shop’ so people like me can order hard copies of the series! How difficult/expensive would it be for you to develop the seven images as separate posters/pictures. I would like to hang them as a series in my hall.
Travis says
October 19, 2007 at 10:06 amHow to feel insignificant!
Neil says
October 19, 2007 at 12:26 pmGratefully received advice of the Queensland Museum Inquiry Centre:
Spider colour is fixed at its previous moult. A slight exception being the abdomen with its much thinner walls which may change especially according to accumulated waste products or what it has eaten. So they can’t change colour like a frog, gecko or squid. Some species of spiders that camouflage on tree bark have multiple colour forms however.
So far as is known, a lichen spider would not be selecting a background according to colour as these are like most (but not all) spiders in having poor vision. I expect it would have other ways of detecting a nice lichen-covered background to sit against however.
Jennifer says
October 19, 2007 at 4:17 pm1. How often does a lichen spider moult?
2. So what ‘other ways’ does the spider have of detecting its background?
3. What about lichen spider T-shirts?
Libby says
October 19, 2007 at 5:25 pmWhat about lichen spider fur coats?
Jennifer says
October 19, 2007 at 9:09 pmWith global warming no more need for fur coats?
Libby says
October 20, 2007 at 6:31 amGood point! Perhaps they will be like the peppered moths of Industrial Era England?!
You could do all sorts of experiments seeing what sort of backgrounds the spiders preferred, etc. Very neat critters.