Tarantula #10 (let’s call him Boris) is not doing what Ian Drummond ’09 and John Havel ’09 want him to do.  Two weeks have passed since Drummond, Havel, and the rest of the animal behavior class conducted their control experiments with the tarantulas—videotaping their gaits, observing said tape, and recording the results. In the interim, the students have been designing experiments that will challenge the spiders in their walking environment. One pair has placed a foamed egg crate in its walking chamber; another has scattered twigs and grass on the floor of its chamber. The purpose is to see if the spiders will adjust their gaits in order to navigate the new terrain.

Drummond and Havel want to see how tarantulas step across gaps—they hypothesize that the spiders’ gaits won’t change—and to answer their query, they have fashioned a one-and-a-half-inch gap by placing two blocks of wood in the chamber. The blocks have identical heights, so the spider will be walking across a relatively level terrain. The widths are the same, too; there are no gaps between the edge of the wood and the wall. Each block covers about half the length of the walking chamber. Almost, but not quite. And there’s that gap, the inch-and-a-half expanse between the blocks.

Boris, though, doesn’t want to step across the gap; he finds it easier to just climb down into the space between the two blocks and sit there. Drummond and Havel narrow the gap to one inch.

Down goes Boris.

“Oh, come on,” says Drummond.

“What if we stack two more blocks on top, doubling the height?” Havel suggests. The idea is that the drop would be significant enough that Boris won’t have a choice but to step across.

But Boris does have a choice . . . and down into the gap he goes.

They try it a few more times with the same result. “OK,”  says Drummond, “let’s try a new spider.”

A few minutes later, spider #24 (we’ll call her Natasha for the sake of the narrative) is introduced into the chamber. She spiders along the first block of wood, reaches the gap, begins to stretch a leg across, and then slowly steps . . . down.

Into the gap.

They try again.

Same result.

Root stops by and has an idea. “What if you were to take two terrariums and place them almost end to end, separated by about an inch and a half. Then place two walking chambers on top of each.” The terrariums are about a foot tall. Surely Natasha wouldn’t want to drop that far.

She doesn’t. But she doesn’t want to step across the gap, either. She simply stops at the edge of the chamber. When Drummond gently prods her with the thin end of a fluorescent green paintbrush, Natasha takes offense.

All eight of her legs seem to move at once (though intellectually we know that’s not the case) and she lets out a hiss.

“Jesus,” Drummond yells, jumping back from the table. “I think it grabbed the brush. I’m sweating. That scared the hell out of me.”

His face is as red as the T-shirt he’s wearing.

“Let’s try a new spider.”

Havel returns Natasha to her terrarium and returns a few seconds later with spider #9, a huge, hairy creature. Let’s call her Shelob.

“She’s a monster,” mutters Drummond. “John, you can do this one.”

Drummond and Havel are now trying a different approach. They’ve placed the two walking chambers directly on the lab table, leaving a quarter-inch gap between the two. Root likens it to creating a puddle for the tarantula to step over. But, like her friends, Shelob wants no part of it.

Drummond and Havel are now an hour-and-a-half into what has proved to be a fruitless experiment. Not one spider has cooperated, and to conduct the experiment properly, the students would have to run three trials—with ten different spiders.

“Maybe we need a new experiment,” Havel says.

Drummond and Havel did conduct a new experiment, placing the subjects on their backs and watched which legs they used to flip over. All the spiders did what they were supposed to do.

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