Tuesday, July 11, 2006

A pile of ...

The image on the right is one which doesn't look like it would inspire a lot of excitement, does it? Presumably you can tell what it looks like: a little pile of bird droppings sitting on a lemon leaf.

Zoom in however (image below), and it tuns out to be not to be a present from an avian visitor but a superbly cryptic arachnid. It's known as the Bird-dropping spider (Celaenia sp.). By night it's an ambush predator, sitting with waiting arms to grab moths that fly by. By day it's a pile of crap - glamourous alter-ego isn't it? You can see how silk is used to anchor the abdomen to the leaf as well as to add some white to the disguise to mimic the pale uric acid excreted by birds. The purpose of this deceit is obvious - nothing really wants to munch on anything that's already been digested by something else (well, except dung beetles).

Oh - and those moths it feeds on; it turns out that they don't just flutter past by accident; the spider actually mimics the pheromone of the female in order to lure males! Read more on the Australian Museum's page on these critters.

1 comment:

Snail said...

Well, look at that! That's the best photo I've ever seen of a bird poo spider.