Naturalist Charles Darwin was on the deck of the HMS Beagle on October 31st, 1832 when he first noticed a strange phenomenon.
The ship was inhabited by thousands of tiny red spiders. They were everywhere.
Being 60 miles offshore, they must have somehow floated over from Argentina’s mainland?
“All the ropes were coated and fringed with gossamer web,” Darwin wrote.
It turns out that spiders don’t need wings in order to fly. They simply raise their abdomens to the sky and release strands of silk which the wind catches and they become airborne.
This could be useful for escaping predators or to relocate over waters or vast stretches of land. It sure seems like an effective means of travel when you’re so tiny.
Spiders have been recorded 2 and a half miles in the air and over 1,000 miles at sea – that’s rather impressive.
It’s believed that the technique, known as ballooning cannot only be the result of wind, since heavier species surely cannot be lifted with such soft winds.
Erica Morley and Daniel Robert seem to have figured it all out. The pair who are based at the University of Bristol have discovered that spiders actually sense the Earth’s electric field and make use of this energy to launch themselves into the air.
Roughly 40,000 thunderstorms occur daily which in turn make the earth a giant electrical circuit, with the upper atmosphere possessing a positive charge and the planets actual surface having a negative one and in foggy or tepid conditions, the gradient could increase in thousands of volts per meter.
The silk picks up a negative charge when released and this creates enough force to lift them into the air. Plants also carry these charges so standing on a twig or leaf gives them a boost and they shoot into the air.
Angela Chuang who is based in Tennessee suggests that it is ever important to know and understand that spiders can actually detect these electrostatic charges.
“[That’s] the foundation for lots of interesting research questions,” she says. “How do various electric-field strengths affect the physics of takeoff, flight, and landing? Do spiders use information on atmospheric conditions to make decisions about when to break down their webs, or create new ones?”
Moonsung Cho from the Technical University of Berlin recently displayed how spiders also in fact raise their front legs to test how strong the wind is.
“This is really top-notch science,” says Gorham. “As a physicist, it seemed very clear to me that electric fields played a central role, but I could only speculate on how the biology might support this. Morley and Robert have taken this to a level of certainty that far exceeds any expectations I had.”
“I think Charles Darwin would be as thrilled to read it as I was,” he adds.