Talking about Spiders (and Millipede Sex)

Warning: The following story contains explicit language about millipede sex.

"Everybody does it differently," explains Petra Sierwald, the Field Museum's friendly myriapod and arachnid expert. "Mammals and humans are rather dull when it comes to their sex life. ... When (the male millipede) mounts the female, it basically has to insert part of its specialized leg into the female sex opening."

Sierwald, a German transplant, oversees hundreds of thousands of myriapods and arachnids lurking in the "sub-basement" of the Field Museum — all stored in alcohol-filled glass jars. A myriapod is a category of creature that includes millipedes and has a segmented body, one pair of antennae and at least nine pairs of legs.

The Field's sub-basement — officially called the Collection Resource Center — isn't typically open to the public, but the Chicago Sun-Times requested a tour because, well, it seemed like a cool thing to do.

Aside from the German accent, Sierwald doesn't fit the stereotype of the reclusive bug scientist — even though she spends about a fifth of her time in the sub-basement, sorting through specimens to be shipped to other researchers around the globe.

She's a scientist with a ready response to every conceivable spider put-down. She's also a savvy promoter of the humble millipede, which explains why she's talking, unprompted, about the many-legged creature's sex life.

But the sex story is merely a showy ploy to highlight the importance of millipedes, which steam across the Earth like a "choo-choo train," munching leaves and forming the vital link in returning forest debris back to the soil.

Sierwald plucks a specimen from a shelf. This particular millipede, from Malaysia, is all curled up, and it's about the size of a golf ball.

"We have specimens as big as baseballs," Sierwald says.

And then it's on to the spiders. Some in the collection aren't much larger than a pinhead — and many of those are from Illinois. There aren't any "ferocious" spiders here, she says.

And then there's a velvety red beauty with leg joints like knuckles.

The Goliath bird-eating spider is the kind of arachnid that can prompt phantom tickling along the nape of your neck. This one came from Suriname.

"It fits nicely on a dinner plate — with its legs stretched out," Sierwald jokes.

Naturally, Sierwald says, there's absolutely nothing to fear from the 40,000 known spider species.

"I'm far more afraid of cars than spiders," she says. Spiders "have to coordinate eight legs, and we sometimes have problems coordinating two."

Sierwald has crawled through the undergrowth in Burma, Panama and parts of Africa in search of spiders for the museum's collection, and she says she has never been bitten.

"I know that doesn't sell newspapers," she says, "but that's the truth."