Over 180 years ago, Charles Darwin went on his iconic voyage aboard the HMS Beagle. He encountered many natural wonders that shaped his views on evolution. But one issue remained a mystery to him—where were all the spiders coming from?
He noticed hundreds of spiders flying and landing on the Beagle in the ocean, even on calm days. Then they would suddenly take off again as if propelled by some invisible force. Biologists from the University of Bristol believe they have the answer—electricity.
The phenomenon is called “ballooning.” Spiders climb to a high point, raise their abdomens in the air, unleash a few strands of silk, and take off. This technique can take them up to 1,600 kilometers (1,000 mi) out to sea. The prevalent theory said that the arachnids used their silks like sails and were carried off by the wind. However, scientists now claim that spiders are drawn up by the electrostatic charge in the atmosphere.
The idea was actually first proposed during Darwin’s time but gained no traction. It was recently resurrected by physicist Peter Gorham. Bristol biologists took it further by proving that spiders can detect electric fields using sensory hairs on their feet. Not only that, but they tiptoe and raise their abdomens in the air, behavior only observed before ballooning.
This research doesn’t discount the idea that wind could still play a role because the same sensors could be used to determine wind speed and direction. However, it does show that electrostatic forces are capable on their own of allowing spiders to fly.
