(ORDO NEWS) — Investigation of spiders (Trichonephila clavipes) in space has shown that these intelligent arthropods can navigate with light when gravity is absent and it is impossible to determine “up”.
“Can spiders weave webs under zero gravity and, if so, how will weightlessness affect it,” a team of researchers from Switzerland and the United States writes in a new article.
“These questions can only be answered by placing the spiders in a zero gravity environment, that is, by sending the spiders into space.”
As part of the experiment, photographs of the cobweb were taken every five minutes, and the light located at the top of the box was turned on and off every twelve hours, imitating daylight.
The two spiders sent into space proved to be quite hardy in their new homes without gravity: the male survived weightlessness for 65 days and was still alive after returning to Earth, while the female weaved 34 webs three times.
But it was the use of light that was directed downward that actually led to the amazing discovery.
“Because under normal gravity and regardless of whether the lights were on, the spiders built asymmetric webs and were positioned head down, so we concluded that gravity is the most appropriate reference point for spiders,” the researchers write.
“We further conclude that the visual stimulus of the direction of light can serve as a guide in the absence of gravity.”
When gravity is at work, spiders happily weave their asymmetrical webs and sit upside down, waiting for prey. In space, their networks were more symmetrical, however, when there was light, the spiders used it as a guide and built their networks as if the light was from the Sun.
“We would not have guessed that light would play a role in orienting spiders in space,” said biologist Samuel Chokke of the University of Basel.
“We are very lucky that the lamps were attached at the top of the box and not on different sides. Otherwise, we would not be able to detect the influence of light on the symmetry of the web in zero gravity.
“It is surprising that spiders have a backup system for this orientation, since they have never been exposed to an environment without gravity during their evolution.”
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