Large spiders take to the air by deploying dozens of thin fibers to catch the wind, a new study published in PLOS Biology reports.
For years, scientists have known that certain spiders are able to use their silk to “fly” to new locations. However, the recent findings — which come from researchers at the Technical University of Berlin — are the first to show exactly how that process occurs.
“The fibers are very hard to observe with our naked eyes,” said lead author Moonsung Cho, a researcher at the Technical University of Berlin, according to New Scientist. “This is why, until now, we have not been able to explain the flight of ‘ballooning’ spiders.”
Gliding spiders spin up into the air on their silk. While scientists have long understood how that process works in spiderlings, it is much harder to explain how large spiders get off the ground.
Previous research suggested they release just a few thick, short fibers, but that would not provide enough lift to take them up into the air.
To solve that mystery, the team in the new study observed ballooning in adult ground crab spiders of the genus Xysticus by raising them in the lab and letting them take off in a wind tunnel.
That revealed the arachnids anchor themselves to the ground before takeoff and use their legs to test the wind. If the conditions are right, the spiders spin out fibers that are roughly 6 to 13 feet long to form triangular sheets.
Then, they spin 50 to 60 ballooning fibers made from much thinner silk. That combination gives them the lift they need to get up into the air.
While most spiders use their fibers to wrap up their prey, crab spiders use it only for flying. Should wind conditions change during the process, the arachnids will cut all of their fibers and start again. If things go well, they cut their anchor line and take off.
This research is important for many reasons. Not only does it shed new light on spider biology, but it also may one day help physicists create better flying machines.
“Over millions of years, these spiders fine-tuned the use of these proteins for certain functions,” Cheryl Hayashi, a researcher at American Museum of Natural History who did not work on the study, told Gizmodo. “I think we could certainly get some ideas from them about aerodynamics and moving things through the air.”