Spider flight mystery solved: electric fields make bug balloonists

Spiders are capable of flying using their silk, a well known ability known as ballooning. The action involves producing silk that, after reaching a few inches in length, lifts the spider into the air and carries it to a new location. The actual mechanism behind ballooning, though, has remained a mystery, with some speculating that it involves air currents. A new study has provided the answer.

Though spiders don't have wings, they're capable of flying across large distances, landing and repeating the process until they've travelled anywhere from a few feet to hundreds of miles. Spiders in the process of ballooning are observed to climb to a high distance, then raise their rear legs and release silk threads into the air.

Wind seems like an obvious answer to the mystery; the silk acts as a sort of parachute that catches a breeze, enabling the spider to sail to its new location. However, there's one big problem: ballooning has been observed in environments where there is no breeze. That observation led to speculation that the Earth's electric field may be the actual answer, but no studies — until now — had tested that idea.

New research out of the University of Bristol has given us the answer: electric fields, not just wind, enable spiders to fly. Spider silk is an electric insulator, and it turns out that the tiny sensory hairs on a spider's legs enable it to sense electric fields. These e-fields, as they're commonly called, can cause lift for ballooning spiders even if there's no wind to carry them.

During their research, biologists found that a lab-controlled electric field could be turned off and on to impact spider ballooning. Turning the e-field on caused the ballooning spider to move upwards; turning it off caused the spider to move downward. The study paves the way for future research into ballooning, including the properties of the silk itself during flight.

SOURCE: University of Bristol