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Aerial Arachnids: Jungle Spiders Glide Between Trees

Here's one more thing you'll need to watch out for in the rainforest: flying spiders — or at least gliding ones. Scientists have discovered that a common species of arachnid can steer in midair after jumping (or being dropped, in the case of this experiment) from high in the jungle's canopy, allowing it land on a nearby tree trunk.

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Lead author Stephen Yaniovak and his colleagues at the University of Louisville have been looking for examples of gliding animals for years. While ants and other insects have performed what the researchers call a "directed aerial descent," spiders have never pulled it off (though they do sail).

This time, the team collected dozens of common spiders known as "flatties" in American tropical forests, the moniker owing to their wide, flattened bodies. The team dusted these test subjects with fluorescent powder, then dropped them from up to 80 feet high and recorded their falls. To their surprise, the flatties homed in on nearby tree trunks a full 93 percent of the time.

"Gliding spiders represent an unlikely if not truly ungainly aerodynamic platform," reads the paper, which appeared in the Royal Society journal Interface. In other words, it works better than anyone expected.

The mechanism for steering appears to be the positioning of the front legs, the authors speculate, though further study will be necessary to confirm it. Spiders that began their falls sideways or upside down immediately righted themselves and flew face-first, suggesting they need to see where they are aiming.

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More research could shed light on the arachnids' method or identify other species that successfully glide — and these "novel mechanisms of body righting and maneuvering" may even be valuable for robots looking to control their descent, Yaniovak wrote.