Sunday, 11 September 2011

more little neighbours

It's been a while since we discussed some of our little multi-leggedy neighbours, so you deserve another installment.

At the end of our corridor, someone has placed some stacks of trays with rock samples outside their office. It's a nice quiet place with comfortable nooks and crannies... there are always open windows as well, so lots of small things for a hungry resident to entertain itself with. The resident in question is a uropygid, also known as a thelyphonid, a whip-scorpion, or a vinegaroon (a bit like a macaroon, but less coconutty).

Including the tail, it's nearly 10 cm long, but the body is a mere 4 cm or so. The tail is a long, hair-like structure that appears to be a sensory device – it certainly doesn’t have a sting, I’m glad to say. Lucy’s glad to hear that too, given that she almost stepped on it in the darkened corridor. (Or should that be, it almost stepped on her? Either way.) They can tell where they’re going by using those weird stringy legs at the front. They’ve evolved these in parallel with the antennae of insects, because uropygids are arachnids, and as such have no antennae. If you watch one of these moving, it will be tapping around in front of itself with those legs, searching for something yummy; its eyes are not that great, although it’s not actually blind, so it probably relies mostly on these to find its prey. This peculiar use of its front legs makes for another parallel with insects, as they only have six legs that they can walk with.

The things at the front are the equivalent of the palps of spiders – they’re not legs, but they evolved from them, once upon a time. They’re now used mostly to catch their unwary prey (mostly insects and millipedes, I’ve heard). The reason for the apparent overkill (although search for amblypygids if you think these ones are good) is that they don’t have a venomous bite, so the damage has to be done with the claws – or at least they have to be sure of holding things still for as long as it takes to nibble through them. Apparently they can’t do much damage to a human handler, although I imagine they’re a bit prickly. I was planning to try with the one in the corridor, just out of curiosity, but my finger thought better of it at the last second. Nothing should look quite so determined to go straight through whatever is in its path.

So why the vinegaroon moniker? Well, they do have a defence mechanism: they can squirt acid at something chasing them. It’s only a weak acid – vinegar plus something extra – but I imagine it might be offputting. Unless, that is, it’s chased by someone who’s quite familiar with fish and chip shops, in which case I guess it’s a self-condimenting treat. But it’s much more fun just to admire it when we get bored of writing papers or doing some statistical analysis. And of course we can leave the door of our office ajar so we can hear the occasional scream from the far end.

For those of a nervous disposition, there aren’t any of these in Europe. Except in pet shops.

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