Newspaper article St Louis Post-Dispatch (MO)

Spiders Spin Crafty Signs into Webs

Newspaper article St Louis Post-Dispatch (MO)

Spiders Spin Crafty Signs into Webs

Article excerpt

THE ROOM beckons warmly and widely, lighted high overhead by gladdening bulbs that recapitulate the brilliance and spectral range of the sun. But as you step into this parlor of a laboratory just try not to jump, or at the very least stiffen.

In every corner, under every surface, dangling into one's hair, brushing against one's shoulder, are large, dainty, lacy, spiraling, glittering spider webs. And tending each of these webs is a large, undainty, big-bellied, generously appendaged spider.

There are dozens and dozens of spiders, some of them yellow, some brownish-black, some pale caramel. And all of them are weirdly frozen in place because - what do you know! - spiders really are more scared of humans than most humans are of them.

"A spider's first impulse when something larger comes along is to stop moving and hope it goes away," said Catherine L. Craig, an evolutionary ecologist at Yale University, who is studying the evolution of spider webs. She taps on a web to prod the little architect from its stupor. It skitters briefly and freezes again.

"There are cultural biases against spiders," Craig said, with some understatement.

"Most people look at my roomful of hanging spiders and it's a nightmare for them. I had one student who came to my lab and volunteered to feed the spiders, but when she saw the spider room, her face contorted like this" - Craig gives her freckled face a Munchian twist - "and she said, `EEEUUUWWW!' "

No such squeamishness for Craig. "I can't think of any place I'd rather be," she said, "than sweating in the sun in Panama playing with spiders."

Craig divides her time between field studies at the Smithsonian Tropical Research Institute on Barro Colorado Island in Panama and laboratory work at Yale with her in-house collection of tropical species of spiders that weave orb webs, including Argiope argentata - a relative of the common garden spider found in the Eastern United States - and Nephila clavipes.

These are the spiders that generate the cobwebs of Halloween fame, as well as the less-familiar ladder webs, funnel webs, hanging webs and other lattices plain or fancy. Their webs are called orbs in the old-fashioned sense of the word, meaning circular.

To Craig, a spider web is not a passive structure or a simple sieve that catches insects that blindly fly into it, as had long been believed. Instead, she views the web as among the spider's most dynamic and responsive traits, a cunning weapon designed to lure prey by exploiting an insect's fundamental need for food, flowers and open spaces.

She proposes that spiders incorporate into their webs visual signals like attractive zigzag designs and faux floral colors that are irresistible to a wide range of insects.

And because these signals are the cues insects use to forage for food, the creatures are not likely to evolve a means of detecting and avoiding the trickster webs without simultaneously jeopardizing their skill for finding a meal.

In an outpouring of reports put together over the last several months, Craig offers evidence for a genuine spider revolution at an unknown point in the past, resulting from minor modifications in the silk proteins of which webs are built. …

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