Selenopid spiders are at constant risk of falling because they live in the canopies of Central and South America’s rainforests.
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And this creepy crawly’s aerial acrobatics are more advanced than mere gliding – it can change direction in mid-air.
A group of biologists working in Panama and Peru spotted a nocturnal hunting spider that is a monstrous two inches across and skydives from trees.
“You’ll see the spider steering as it goes through the tree”, Yanoviak says.
As usual, the research only marks the beginning of the never-ending process of discovery.
This time, the team collected dozens of common spiders known as “flatties” in American tropical forests, the moniker owing to their wide, flattened bodies.
The then dropped them from 65 to 80 feet (20 to 25 meters) from trees and filmed them maneuvering in the air. They are “wafer thin”, Dudley says, and flexible; they maneuver by spreading their legs wide in order to use lift and drag to steer themselves toward the tree trunk when they fall.
“These spiders represent a remarkable evolutionary adventure in the animal conquest of the air”, study researcher Stephen Yanoviak, from the University of Louisville in Kentucky, and colleagues said.
“In other words, we started dropping a lot of stuff out of trees”, he continued, adding that “we were pretty surprised to see these spiders glide”, given that there were no earlier published anecdotal reports documenting the behavior.
What they conclude is that a strong selective pressure in the environment exists against spiders that have otherwise uncontrolled descents from trees to the forest floor. There is, however, no need for immediate concern that spiders will sprout wings.
How can spiders, which are not flying beings fly, wonder scientists.
“My guess is that many animals living in the trees are good at aerial gliding, from snakes and lizards to ants and now spiders”, Dudley said.
‘If a predator comes along, it frees the animal to jump if it has a time-tested way of gliding to the nearest tree rather than landing in the understory or in a stream’.
The scientists believe that for spiders, gliding is a way of avoiding the ground, which is likely to be full of potential predators. While scientists thought this was simply an unavoidable danger of the spider’s lifestyle, it turns out that the arachnids are smarter than previously thought.
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Despite the observation, Yanoviak said it was uncertain whether the leg movements actually steered the airborne spiders. “However, the wingless immature stages of various insects that are winged as adults can also glide really well”.
