Science Explains How These Spiders Can Fly
Spiders can't actually fly. But, much like humans, they've developed the ability to take to the air despite their physical limitations.
How? Well, these crafty arachnids spin silk parachutes to glide through the air effortlessly.
The technique is called "ballooning," which can be seen in newborn spiderlings as well as in larger adult spiders. The latter is harder to understand, but now scientists have released their comprehensive observations on the arachnid's amazing abilities.
Spiders Learn To Fly
In a study published in the journal PLoS Biology on Thursday, June 14, researchers conducted laboratory and field tests to observe the spiders ballooning capabilities. The team chose adult ground crab spiders to analyze, a species that can weigh from 16 to 20 milligrams.
Large spiders have been believed to produce just a few thick fibers, but the study reveals that they actually spin dozens of very thin fibers to make their paragliders.
"The fibres are very hard to observe with our naked eyes," Moonsung Cho, coauthor and aerodynamic engineer from the Technical University of Berlin, Germany, explains in New Scientist. "This is why, until now, we have not been able to explain the flight of 'ballooning' spiders."
The team observed that the spiders produce fibers for ballooning that are about 2 to 4 meters (6.5 to 13 feet) long, then create triangular sheets from them.
There are reportedly different types of silk produced: a thick one that has a diameter of 700 nanometers, and a thinner one that measures only 200 nanometers. The spiders spin two of the thick fiber and 50 to 60 of the thin one, which is enough to lift up heavier spiders — with the proper wind conditions.
Perfect Flight Conditions
Impressively, spiders make sure the conditions are perfect before taking to the air. The process is very deliberate with the creature securing itself with a safety line, then lifting one leg to check the wind conditions. For them, the perfect flight conditions consist of wind moving below 3 meters per second (7 miles per hour) with light updrafts.
"From our observation, it seems obvious that spiders actively evaluate the condition of the wind with their front leg ... and wait for the preferable wind condition for their ballooning takeoff," the scientists noted in the study.
If the wind continues favorably, the spider can keep flying. However, if the conditions suddenly changes, they sometimes cut the fibers and simply start from scratch. During slow launches, creatures sometimes keep the safety line attached to the platform until it's 5 meters (16 feet) long.
What the researchers of the new study have not yet explained is how the fibers don't get entangled even with dozens of it in the air. Previous researches have suggested electrostatically charged fibers, which is still entirely possible.