Arachnid aviation - ballooning

Andy Fry

WildCall Officer

Spiders aren’t the first creatures that spring to mind when you think of flying animals, but you’d be surprised – some spiders are in fact very accomplished aviators.

Spider egg sacs can contain anywhere from a few spiderlings to a thousand or more. With so many siblings in such a small space, it can be hard for a young spider to find a place to settle. Many species have developed an ingenious solution to this problem: flight.

In order to create some space between them and their siblings-come-competitors, spiderlings climb to a high place, cast a number of fine silk threads upwards, and take to the skies in a process known as ‘ballooning’. It was once thought that ballooning spiders sail on the wind, but recent studies show that they in fact rely on Earth’s electric field to carry them into the air. They are able to detect static electricity using hairs on their abdomen, and when conditions are right, they point their abdomen skyward and lift off. This behaviour is also sometimes seen in adults, but it is suspected that they need a boost from air currents to get them airborne.

The majority of these airborne journeys only last a few metres, but a spider caught in a jet stream can travel hundreds of miles in one trip. Spiders have been found floating on silk nearly three miles in the air, and a thousand miles out to sea. Rather unbelievably, a study in the 1920s revealed that one in every seventeen invertebrates found high above the ground was a spider.

While it is a risky strategy, spiders have proven that you do not need wings to fly – so long as you weigh next to nothing, produce silk, and can detect electrostatic charge.