Spiders Use Their Silk to Go Ballooning for Thousands of Miles on Electric Fields

The aerodynamic capabilities of spiders have intrigued scientists for hundreds of years. Charles Darwin himself mused over how hundreds of the creatures managed to alight on the Beagle on a calm day out at sea and later take off from the ship with great speeds on windless day. Scientists have attributed the flying behavior of these wingless arthropods to “ballooning,” where spiders can be carried thousands of miles by releasing trails of silk that propel them up and out on the wind. However, the fact that ballooning has been observed when there is no wind to speak of, when skies are overcast, and even in rainy conditions, raises the question - how do spiders take off with low levels of aerodynamic drag? Biologists from the University of Bristol (UK) believe they have found the answer. "Many spiders balloon using multiple strands of silk that splay out in a fan-like shape, which suggests that there must be a repelling electrostatic force involved," explains lead researcher Dr. Erica Morley, an expert in sensory biophysics. "Current theories fail to predict patterns in spider ballooning using wind alone as the driver. Why is it that some days there are large numbers that take to the air, while other days no spiders will attempt to balloon at all? We wanted to find out whether there were other external forces as well as aerodynamic drag that could trigger ballooning and what sensory system they might use to detect this stimulus."
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