Friday, September 02, 2011

Do spiders really eat their own webs?

I've heard that they do.  And I've seen spiders appearing to be eating their webs. So last week, when I was at the arboretum, pointing out to visitors a huge and beautiful garden spider spinning her web between two trees, I didn't hesitate to say yes when a lady asked, "Is it true that they sometimes eat their webs?"

Now, I'm not so sure.

Spider in web
I have been doing a fair amount of spider-watching lately.  And watching out, because they have been building webs right in front of my porch, and in other places that might get me a face full of spider if I'm not careful.  And the other night, with nothing better to do, I watched as one spider made a huge web.  It was literally an orb and a half, with an extra section tacked on to one side.  Clearly, she was hoping to snag every flying insect that was headed for my porch light.

There was another spider building a web off my back porch.  But for some reason, part way through, she aborted the mission.  Without warning, she ran up one of the side support lines and detatched it from the patio roof.  Then she ran across the collapsing structure to the opposite end, seemingly gathering up the slack as she went.  In a few seconds, the web was completely gone, and so was she.  But, did she eat it?

web line

Back out front to the huge web on my porch:  How could a spider eat something that big?  The next morning, the spider and her web were still there.  Usually these spiders will retreat to a safe place during the day and rebuild a new web in the evening, so I didn't feel too bad about giving her a little start and sending her up under the eaves.  Now her web was mine to play with.

I recalled how the spider on my back patio undid her web and gathered it up so quickly, so I decided to try to do the same with this one.  I grabbed it from one end and gently pulled and twisted so that it stayed in one piece even as I rolled it between my fingers.  Amazing how strong the supporting lines were.  And not sticky.  The main part of the web was very sticky, though.  Anyway, I rolled the whole thing up with my thumb and forefinger, and found that the original web, which must have been 18 inches across, and all the support lines, that extended for several feet, ended up rolling into a little tiny ball of silk about the size of a poppy-seed!

Ok, so size-wise, I guess a spider would have no problems eating that.  But wait a minute....spiders don't really eat.  I mean, they don't chew their food.  Their venom pre-digests and liquifies the insides of their prey, and they drink the resulting liquid, leaving the exoskeleton like a discarded husk.  So would they even have a way to eat that dense little poppy-seed of silk?  Maybe swallow it like a pill?  Maybe somehow, they re-liquify it, so they can drink it?  Or do they just discard it?

I have tried to find out more information online.  Wikipedia says they do eat their webs, but it's Wikipedia:  unverified and possibly inaccurate.  I found another website called Spiderz Rule! which also says they eat their web, but they still don't explain how it happens, just that they do.

Orb Weaver

If anyone has any information about whether or how spiders eat their own webs, please do tell!

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