MICHEL MARTIN, HOST:
So I'm thinking we've all seen a spider spinning a web at some point - probably a web that functions as a kind of barrier to ensnare unsuspecting insects. Turns out another kind of spider uses its web to trap its prey differently. Here's science reporter Ari Daniel.
ARI DANIEL, BYLINE: Entomologist Sarah Han has always been into spiders. As a girl, she collected them and learned a fundamental principle of the spider-verse.
SARAH HAN: There's a huge diversity of webs and the ways that spiders use these webs to try to catch prey.
DANIEL: Take the tiny ray spider. It's smaller than a grain of rice, and it spins its web with those classic concentric circles with spokes. But then the spider strings a thread from the center of the web to a nearby rock or twig. It then grabs the middle of the web and then pulls itself along that tension line.
HAN: And that is what turns that web from a flat shape into a cone shape.
DANIEL: The conical web is now spring-loaded. When an insect flutters by - zing - the spider releases the tension line, flinging the web forward and entangling the prey.
HAN: So they're not just passively sitting there. They're using the web like a slingshot without the insect ever touching the web.
DANIEL: Which is unusual. Han wanted to know how the ray spider figures out when to propel its web through the air. So during her PhD at the University of Akron, she collected ray spiders from the local metro parks, along with a bunch of mosquitoes. Back in the lab, she glued those mosquitoes to little paper strips.
HAN: We started calling them mosquito lollipops 'cause it was just, like, this mosquito flying around at the end of this stick.
DANIEL: All while recording everything using high-speed video. Three out of four times, when she moved the tethered mosquito towards the front of the cone, the spider launched its web.
HAN: It's just, like, instantaneous, practically. They would never really see it coming.
DANIEL: Han then tried the same experiment with a tuning fork that vibrated at a frequency akin to an insect beating its wings - just way stronger.
HAN: They would release their webs from much farther away. So the ray spiders will release their webs in response to airborne prey vibrations.
DANIEL: Determining both the direction and distance to those vibrations.
HAN: The web is kind of like the spider's ear.
DANIEL: The research is published in the Journal of Experimental Biology. Symone Alexander is an engineer at Auburn University. She says spiders are masters of designing webs that allow them to detect stress and strain precisely.
SYMONE ALEXANDER: These spiders - the geometry of their web is slightly different, and it's tensed in a different way. Can we use that as inspiration for building the sensing systems in airplane wings or other materials?
DANIEL: In other words, inviting the spider-verse to improve the human-verse. For NPR News, I'm Ari Daniel.
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