Scientists discover skydiving spiders in forests of South America

Scientists believe the ability to glide preceded the evolution of flight.

By Brooks Hays

BERKELEY, Calif., Aug. 19 (UPI) -- It's already well established that spiders and can jump, fly and even sail across water. Apparently, they can skydive, too.

Scientists already knew spiders traveled via air. But these parachute-launching spiders are at the mercy of the wind. Researchers say skydiving spiders in the forests of South American can manipulate their flight.


The nocturnal hunting spider, a member of the genus Selenops, is a tree dweller. Occasionally, the spider is forced to abandon its home or is blown off by a swift breeze. When this happens, the spider doesn't simply fall from the tree like a rock. Instead, it manipulates its wafer-thin, two-inch-wide body to guide its trajectory to the safety of another branch or tree trunk. The spiders are also able to right themselves if they begin to fall upside down.

When researchers in Peru and Panama tested other arachnids, the creatures were unable to steer themselves to safety and simply dropped to the floor.

Scientists believe controlled descent led to the ability to glide, which preceded the evolution of flight.

"My guess is that many animals living in the trees are good at aerial gliding, from snakes and lizards to ants and now spiders," Robert Dudley, a professor of integrative biology at the University of California, Berkeley, said in a press release. "If a predator comes along, it frees the animal to jump if it has a time-tested way of gliding to the nearest tree rather than landing in the understory or in a stream."


Dudley and his colleagues in South America documented 59 instances of guided flight by the hunting spiders. On several occasions, the falling spider bounced off the trunk but was then able to redirect its flight, once again, and land back on the trunk on the ricochet.

Dudley's field and lab findings are detailed in the journal Interface.

As usual, the research only marks the beginning of the never-ending process of discovery.

"This study, like the first report of gliding ants, raises many questions that are wide open for further study." said Stephen Yanoviak, a professor of biology at the University of Louisville. "For instance, how acute is the vision of these spiders? How do they target a tree? What is the effect of their hairs or spines on aerodynamic performance?"

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