Electrically Charged Spider Webs Snatch Prey and Pollutants

Most people are familiar with how spider webs work. A fly or other insect becomes entrapped in the sticky strands on the web and are unable to break free. Now, though, scientists have discovered that spider webs are far more active than we might have thought. They've shown that webs actively spring toward prey thanks to electrically-conductive glue spread across their surface.

A type of natural "glue" coats the strands of spider webs. It's this glue that possesses electrostatic properties that causes the web to reach out and grab all charged particles-from pollen to pollutants to flying insects. Glue spirals can also distort Earth's electric field within a few millimeters of the web, which could potentially allow insects to spot the webs with their antennae.

"The elegant physics of these webs make them perfect active filters of airborne pollutants including aerosols and pesticides," said Fritz Vollrath, one of the researchers, in a news release. "Electrical attraction drags these particles to the webs, so you could harvest and test webs to monitor pollution levels-for example, to check for pesticides that might be harming bee populations."

That's not all the webs could be used for. Scientists could also employ spider webs to detect airborne chemicals just by looking at the shape of the webs. Since many spiders recycle their webs by eating them, they would also ingest any particles on the webs. Spiders then spin different webs depending on what chemical is affecting them; for example, spiders spin beautiful webs when on LSD but terrible web shapes when on caffeine.

"People often underestimate the static electricity that builds up in airborne objects, but it is important at all scales," said Vollrath in a news release. "The Hindenburg disaster might have been caused by a discharge of static electricity, and helicopters have been known to explode if they discharge suddenly when landing. Everything that moves through the air develops static charge, so it's fascinating to see how spider webs make use of this to actively catch prey. It's a great bonus for us that this also causes them to attract pollutants, making them a cheap and natural way of tracking pesticides and air quality around the world."

The findings are published in the journal Naturwissenschaften.

Want to see the spiders moving toward positive and negative electrodes? Check out the video here.