New Research Shows Crab Spiders Are Remarkably Good at Flying With 10-Foot Web Parachutes

Sunday, 17 June 2018 - 3:04PM
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Weird Science
Sunday, 17 June 2018 - 3:04PM
New Research Shows Crab Spiders Are Remarkably Good at Flying With 10-Foot Web Parachutes
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Flickr/John Flannery
Some spiders can jump. Others can burrow. More than you might expect can paraglide.

New research on spider flight published in the journal PLOS Biology looked at a long-observed but not well-understood behavior found in spiders, specifically crab spiders: their ability to form a parachute out of their webbing, and use it to take flight on passing winds. By doing this, the spider can quickly find a new place to find food or lay eggs, and it helps the species spread very quickly.

The technique is called "ballooning", and it's not entirely clear how it works. To get a better understanding of how spiders can hang loose like this, Moonsung Cho from the Technical University of Berlin assembled a sample of 14 crab spiders and placed them on an outdoor mushroom-like structure during a windy day, to take close observations as the spiders gradually built themselves a web "balloon" and took off.



Since crab spiders are among the larger spider species which can balloon, being about 0.2 inches (5 millimeters) long, Cho didn't need any highly fancy equipment to get some great footage of the spiders at work. The research was successful, and Cho got some of the best ever footage of the spider ballooning process from start to finish.

The experiment also revealed some new details about the spiders' behavior. While assembling the parachute, the spiders use small amounts of webbing to stick themselves to the ground to avoid taking off too early. And before the spiders actually launch themselves, all of them would stick out a single leg to check the winds and see if they're suitable. It's an impressively clever procedure from the little guys.

There were limits on how fast winds could be going, as the spiders would only take off if wind speeds were less than 7 miles per hour (3 meters per second) to avoid any dangerous paragliding conditions. The balloons themselves were made of up to 60 fibers of webbing, and while they were extremely thin, they could extend out to 10 feet (3 meters) long.

It's a fascinating alternative to flying that insects are capable of, so if you ever see an arachnid a safe distance away, don't assume it couldn't close that distance. Wind conditions permitting, of course.

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