“As the researchers note in their study, which now appears at the Royal Society journal Interface, “[This] discovery of targeted gliding in selenopid spiders further indicates strong selective pressures against uncontrolled falls into the understory for [tree-dwelling species]”.
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The then dropped them from 65 to 80 feet (20 to 25 meters) from trees and filmed them maneuvering in the air.
To test and study the Selenops spider’s gliding capabilities, Dudley and Yanoviak threw 59 individual spiders from a height and observed how they fell. It changed the angle of the right front leg when it turned left.
Professor Yanoviak discovered a decade ago that some species of ants are capable of gliding.
Their “drop tests” have shown that many ant species can “hang glide”, making controlled aerial descents, as do immature praying mantises and grasshoppers.
“Overall, these spiders represent a remarkable evolutionary adventure in the animal conquest of the air”, conclude the authors in their study.
“As far as adult arthropods are concerned, only ants, bristletails and spiders use directed aerial descent”, Yanoviak said. Researchers set about finding out if spiders of the genus Selenops, nicknamed “flatties”, might also be able to glide to safety.The method was simple: the scientists dropped the spiders from treetops. But the spiders don’t use webbing between their legs.
The researchers think that the gliding behavior of the Selenopid spiders, which often run away when disturbed and jump off branches when they are pursued by predatory ants, has evolved because falling to the ground can be fatal for these spiders as they are likely to be eaten by predators.
“It’s awesome to see them do it. They’re so good at it”, he said.
This is an incredible ability for the insect because it also allows it to protect itself from various predators such as birds or fish that could otherwise feed on it. These include cockroaches, mantids, katydids, stick insects and true bugs’. How do they target a tree?
To capture flatties for the new experiments, Yanoviak and his team climbed trees in the Panamanian jungle, where they climbed trees and popped plastic bags over any spiders that betrayed themselves by scuttling away.
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The scientists say that this type of behavior may have preceded the origin of wings. This is actually a superior process to that of ballooning, that is performed by other types of spiders who are able to direct their flight in the right direction by releasing silk as they fall.
