Spider webs are one of nature's most impressive marvels; even the tiniest of spiders—with equally tiny brains—can spin intricate, geometric webs. These arachnid architects have both astounded and puzzled scientists for ages, but a new study published last month in the journal Current Biology unravels the spiders' secrets.
A team of scientists at Johns Hopkins University used night vision and artificial intelligence (A.I.) tools to track spiders' movements—down to the precise placement of their legs—as they wove their webs. The analysis revealed that spiders have their own "choreography," reports Jennifer Ouellette for Ars Technica.
Study coauthor Andrew Gordus, a behavioral biologist at Johns Hopkins University, was out birding with his son when they stumbled upon a beautiful spider web.
"I thought, 'If you went to a zoo and saw a chimpanzee building this, you'd think that's one amazing and impressive chimpanzee,'" he says in a press release. "Well, this is even more amazing because a spider's brain is so tiny, and I was frustrated that we didn't know more about how this remarkable behavior occurs."
To investigate, Gordus and his team studied six hackled orb weaver spiders, a species belonging to a group that creates spiral wheel–shaped webs. This species is nocturnal and was chosen because they're active throughout the year and small in size, reports Ars Technica.
Each night, the spiders were placed in a plexiglass box to build their webs. Using an infrared light to see at night, a camera captured all their movements as they wisped around the enclosure constructing their webs. But manually combing through hours' worth of camera frames looking at each spider's legs wasn't going to be an easy feat, Alice Lipscombe-Southwell reports for BBC's Science Focus.
"It's just too much to go through every frame and annotate the leg points by hand so we trained machine vision software to detect the posture of the spider, frame by frame, so we could document everything the legs do to build an entire web," says lead author Abel Corver, a graduate student at Johns Hopkins.
The software's analysis revealed that spiders build in well-organized stages. First, they explore the space and build a prototype. Then they build the frame and radii, or the strands that stretch from the center to the edge. After that, they'll start weaving the spiral, which likely stabilizes the web. After hours of weaving, the spider hunkers down in the center of the web, waiting for an unassuming snack to get trapped, reports Ars Technica.
"We've defined the entire choreography for web building, which has never been done for any animal architecture at this fine of a resolution," Gordus says in the press release.
The team also discovered that the spiders exhibited very similar movements to the point that the team could predict what part of the web a spider was building solely based off of its legs' positions, reports Daniel Maslowski for WUTR in Utica, New York.
"Even if the final structure is a little different, the rules they use to build the web are the same," Gordus says in the press release. "They're all using the same rules, which confirms the rules are encoded in their brains. Now we want to know how those rules are encoded at the level of neurons."
This research has led the team to wonder what parts of the spiders' brains are responsible for the different phases of web weaving, which they plan to test out using mind-altering drugs, according to the press release. Corver also hopes that this research could shed some light on how the circuits in our own brains work since animal brains are built out of the "same fundamental building blocks," he says.