Scientists Have Spider Sense

Spiders found some diehard fans in researchers at this week's American Arachnological Society conference in Baltimore

June 23, 2006|By DENNIS O'BRIEN | DENNIS O'BRIEN,SUN REPORTER

Arachnologists are used to it. Whenever they tell someone what they do, the reaction is predictable.

Eeeeeewwwww!

That's because they work with spiders.

"You're almost a little self-conscious about the stuff you do," said Matt Persons, a biologist at Susquehanna University in Pennsylvania who was in Baltimore this week for the American Arachnological Society's 30th annual conference. "But most times people will also tell you their spider story, even though they get `icked out' by it. Then they will start asking questions."

Spiders live in sticky webs, eat each other and sometimes bite.

But researchers say the eight-legged creatures make ideal study subjects. Spiders learn new behavior, can be fussy about mates, weave intricate webs with a variety of silks and will react to what they see on a television screen. That's right, they watch television.

FOR THE RECORD - An article in Friday's editions misstated the background of a biologist, the date of a lab vandalism incident and the diet of one of the spiders that he studies. Matt Persons earned master's and doctoral degrees at the University of Cincinnati, where a lab was vandalized by an animal rights group in the mid-1990s. The wolf spider is a predator that does not feed on vegetable matter and detritus in the soil.
The Sun regrets the errors.

"There's so much variety in how they build webs, behave, eat and catch prey," said Nancy Kreiter, a biology professor at the College of Notre Dame of Maryland. The school hosted the conference, which attracted about 135 spider experts.

There are an estimated 38,000 species of spiders in the world. A fossil found in upstate New York shows spiders have been around for about 380 million years.

Still, much about them remains unknown and researchers say there is a distinct advantage to studying such an unloved animal: a lack of concern among animal rights groups.

In 1991, when Persons was an undergraduate at the University of Cincinnati, an animal rights group vandalized the university biology lab and released a roomful of congenitally deaf mice. But the intruders left the spiders' lab untouched.

"Spiders don't generate a lot of sympathy," Persons said.

Yet there are those who admire spiders for what they can do.

"Spiders are not particularly popular, but that doesn't mean they're not cool," said George Uetz, a biology professor at the University of Cincinnati.

Ounce for ounce, the silk woven by the cribellate orb-weaving spider to catch and hold prey is stronger than steel, experts say. It only seems to break so easily because it is so thin -- as little as 1/50th as thick as a human hair, said Todd Blackledge, a biology professor at the University of Akron in Ohio who studies the strength and elasticity of spider silk.

Blackledge told his fellow researchers this week that he and a colleague recently found a unique quality in cribellate spider silk that makes it stickier and stretchier than other silks: a core thread surrounded by finer, nano-sized fibers.

When the core thread breaks, the silk continues to stretch, eventually doubling in size because the nano-sized fibers surrounding it continue to hold it together.

Blackledge and Cheryl Hayashi, a biology professor at the University of California, Riverside, say their work could help develop synthetic fabrics with the strength and elasticity of spider silk for use in high-performance cables, sportswear and other products. Current research is focused on replicating the proteins that give spider silk its strength.

"People are working on this all the time," Hayashi said.

Other scientists are using a variety of tools to study spiders, including video cameras, nail polish and electric shocks.

Uetz has been studying spider behavior on videotape since the 1980s. Recently, he's been digitally modifying how spiders look on film to see whether it affects the behavior of other spiders watching them on Walkman-sized television screens.

"The odd thing, if it is an odd thing, is that some have really acute vision," he said.

Wolf spiders, like humans, size each other up before mating, Uetz says. He altered the appearances of some males by digitally shaving some bristles off their legs and found that females liked unshorn males. That is, they were quicker to initiate the elaborate signals they send when they are ready to mate. (Turning slowly and extend their legs upward.)

Uetz prefers using spiders for his work precisely because so much remains to be discovered. "They're less known than other animals, so everything you see is new," he said.

Eileen Hebets used nail polish to develop conclusions about spider mating preferences that she says have implications for human behavior.

Hebets, a biology professor who keeps 3,000 spiders in her lab at the University of Nebraska, painted the legs of male wolf spiders a dark color and then exposed the marked spiders to immature females.

Such detailed painting is not that difficult, she said. "You put them in a Ziploc bag, cut a hole in the corner of the bag and sort of guide it to the corner with your hand and pull a leg out under a dissecting microscope."

The hardest part of her 2003 study was finding a shade of nail polish close to a color of the spider's legs.

A few weeks later, when the females had matured and were given a chance to mate, they preferred mates with that same shade on their legs.

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