TORONTO -- A team of scientists from Switzerland and the United States say that spiders are able to use light to orient themselves while weaving their webs in the absence of gravity in space.
Two juvenile spiders were brought to the International Space Station for a two-month observation with zero gravity in May 2011. Another pair of spiders were kept in otherwise identical conditions on Earth over the same period. During that time, the spiders and their webs were photographed every five minutes to monitor for any changes in the design of their webs.
The findings of these experiments were recently published in The Science of Nature.
Scientists say Trichonephila spiders typically build asymmetric webs with the hub – the place where the web's strands meet – located near the upper edge of the web. The spider then positions itself at the hub facing downwards as they wait for their potential prey to approach.
The asymmetric lines are considered by scientists to be linked to gravity. When scientists examined the webs of the spiders that were placed in space-like conditions with zero gravity, they noticed that most, but not all of the webs built in zero gravity were more symmetric.
Researchers also found that spiders building webs with no gravity showed a random orientation but only during the time when the lights were turned off, suggesting that light replaced gravity as a guide for how the spider would sit on the hub of the web.
“Closer analysis revealed that webs built when the lights were on were more asymmetric (with the hub near the lights) than webs built when the lights were off,” the study says. “Spiders showed a random orientation when the lights were off but faced away from the lights when they were on. We conclude that in the absence of gravity, the direction of light can serve as an orientation guide for spiders during web building and when waiting for prey on the hub.”
New developments have led scientists to conclude that while gravity is the most relevant orientation guide for spiders, the direction of light can also serve as a guide in the absence of gravity.
