The eight-legged beasts, it turns out, are skilled aviators-testing out the wind with their front legs until they find the ideal breeze.
Although scientists have studied spider flight before, this is the first time someone's taken a serious look at the mechanisms behind the phenomenon.
Through a combination of field observations and wind tunnel experiments, they found that large crab spiders (Xysticus species), about 5 mm long and weighing up to 25 milligrams, actively evaluated wind conditions by repeatedly raising one or both front legs and orienting to the wind direction.
Cho gathered a sample of 14 spiders and took them to a park in Berlin and placed them on a domed sculpture to watch the way they interacted with natural winds.
"The pre-flight behaviors we observed suggest that crab spiders are evaluating meteorological conditions before their takeoff", stated the study author Moonsung Cho (Technical University of Berlin). Cho added that "ballooning is likely not just a random launch into the wind, but one that occurs when conditions most favor a productive journey".
They then spin out ballooning fibers that are up to 13 feet long and make triangular "sheets".
Each of the strands produced by the spider was on average thinner than the wavelength of visible light, which ranges from 400 to 700 nanometers.
The researchers found that when wind speeds were below seven miles per hour with light updrafts, the spiders spun out up to 60 threads measuring three meters long and launched themselves from an anchoring line that was attached to a blade of grass.
Reasons for travel? Parachuting spiders might be looking for a good place to eat, love or a new place to call home.
From the physics perspective, this flight method works for spiders thanks to the air's viscosity compared to the extreme thinness of their silks.
Many of us are terrified by flying cockroaches and to make matters worse, scientists have confirmed that spiders can also fly and also figured out how. The last thing the spider has to do is to release the anchor strand, which allows the silk to leave the creature into the sky.
Watching this impressive behavior again and again, the researchers discovered the ideal conditions for a creepy crawly cruise; a gentle breeze of around seven miles per hour with a light updraft.
Cheryl Hayashi is a spider biologist with the American Museum of Natural History. "It gives you a deeper appreciation for how spiders have evolved to do this feat-they're literally sailing through the air", she said, as reported by the website.
Crab spiders like this one reach out with a limb to assess the wind before deciding to fly.
"Over millions of years, these spiders fine-tuned the use of these proteins for certain functions", including flying, Hayashi told Gizmodo.