Why do spiders sit on their webs pointing head-first downwards?

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Offline chris

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I have received a question from Keith in the US asking why you never see spiders sitting on their webs point face up to the sky.

I cannot find anything about this. Has anyone any ideas?

The only lame thing I can think of is that they are less likely to get sun in their eyes if they look downwards, which might blind them to predators, and there might be some benefits in relation to rain...

Chris
I never forget a face, but in your case I'll make an exception - Groucho Marx

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paul.fr

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personally i thought spiders tended to stay on the edge of the web and use vibration. as for their eyes, i found this.

Quote
Introduction
Spiders usually have eight eyes (some have 6 or fewer), but few have good eyesight. Most are able to detect little more than light-dark intensity changes and rapid movement - enough to stimulate nocturnal web building, hunting or wandering activities, as well as to allow rapid reactions against daytime predators (e.g., by dropping from webs). Some spiders have median eyes that can detect polarised light and they use this ability to navigate while hunting. For most night-active spiders sight is unimportant compared with touch, vibration and taste stimuli.

For a few spiders good vision is vital for hunting and capturing prey and for recognising mates and rivals. They include the day active jumping spiders and flower spiders, and the wolf spiders and net-casting spiders, more often seen by twilight or later at night.


here: http://www.amonline.net.au/spiders/toolkit/hairy/see.htm

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Offline chris

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Orb weavers very often stay in the middle I've noticed.

Chris
I never forget a face, but in your case I'll make an exception - Groucho Marx

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Offline ukmicky

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It may have something to do with the sex of the spider, i've heard whilst females  prefer to go down your average male  prefers to go up.  [;D]

Sorry.

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Offline dentstudent

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Perhaps: When there is dew or rain, it tends to collect and hang from the underside of objects. If the spider were facing down, it would drown? I've yet to see a spider with a snorkel, so I'm convinced this is correct!

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paul.fr

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There was some information in the link, i posted, previously.

Alternatively, could it not just be that when you approach the spider in it's web, that it looks down as if to hide?

or maybe we don't see enough spiders, going about their business to notice when they look up.