07 November 2009

Spider at the old palace, Gujarat

Spider on webAt the old palace somewhere in Gujarat, the spiders rule now. This, with its legs outspread in this characteristic manner, was about the size of my palm.

All content © 2009 Pete McGregor


P.E.A. said...

Wonderful! But why does it do that four-legged trick - is it pretending not to be a spider?

robin andrea said...

Nice to see such a big spider. Interesting zigzag pattern in the web, like the Argiope aurantia's webs I've seen in our yard.

pohanginapete said...

P.E.A. and Robin Andrea, the zigzag patterns are called stabilimenta and various theories about their function have been put forward. One is that they help camouflage the spider, and although it doesn't seem particularly effective in this photo, in practice it might work much better. Seeing the distinctive way this spider holds its legs, it's hard not to think it's aligning its legs with the stabilimenta — perhaps so it looks less like a spider? But surely birds would quickly learn to recognise that?

Another theory is that stabilimenta make the webs more conspicuous to birds so they don't fly through them; another is that because the silk used in the stabilimentum strongly reflects UV light it attracts insects. Of course, stabilimenta might have several functions; e.g. there seems no reason why they couldn't warn birds and attract insects.

I'm not sure what the species is, but a reasonable guess would be one of the Argiope species, particularly because some of those hold their legs in the same pattern (e.g. the St Andrews Cross spiders).