Spiders are able to fly at high altitudes and across long distances through a behavior named ballooning, and a new study revealed that the Earth's electric field gives the insects' flights a boost.
Spider ballooning has been known for a while by scientists. However, the exact specifics of the mechanism behind the mysterious behavior have gone unexplained, until now.
How Do Spiders Fly?
Scientists have figured out the step-by-step process of spider ballooning, which the insects do when searching for food, finding a new home, or escaping danger.
Spiders stand on tiptoe with their abdomens pointing up and release silk filaments, which are then carried by the wind, allowing them to "hitch a ride." A recent study discovered that the spiders actually strategize before ballooning, as they determine whether wind conditions are favorable for flight before deploying their silk.
In a new study that was published in the Current Biology journal, the University of Bristol's Erica Morley noted that ballooning only happens during low winds, such as light breezes. Some bigger spiders are also able to fly even when it looks like the wind is not strong enough to pick them up. In addition, scientists have not determined what causes mass ballooning events, which sees thousands of spiders simultaneously taking to the air.
These things hint that spider ballooning relies on something else aside from just the wind.
Flying Spiders use Earth's Electric Field
It has been suggested that the Earth's electric fields may affect how spiders fly, but there has been no evidence to prove this until the study carried out by Morley and her colleague Daniel Robert.
Morley and Robert proved that spiders are able to detect electric fields by placing them on vertical strips of cardboard inside a plastic box. They then generated electric fields that are similar in strength to what the insects experience in outside environments. This ruffled the tiny hair on the spiders' feet, known as trichobothria, and they started standing on the ends of their legs and sticking their abdomens in the air. Spiders only do this before ballooning.
In fact, some of the spiders were able to fly, even while inside the closed boxes with no wind passing through them. When the electric fields were deactivated, the ballooning spiders fell back down.
While the researchers believe that air currents still play a part in ballooning, Morley and Robert were able to show that the Earth's electric field is enough to send spiders flying into the air.