Two science experiments at the International Space Station (ISS) have shown that spiders can build webs in a non-gravity environment, they just need one simple resource: light.
Without gravity, when there's no sense of up or down, a light source helps spiders know where up and down are. A recent study published in the journal Science of Nature outlines the fascinating experiments.
Orb web spiders weave asymmetrical webs when on Earth, thus when in gravity. But without gravity, they were spinning symmetrical ones, showcasing abnormal behavior.
When a light source was added to the spiders' environment on the ISS, they weaved asymmetrical ones, just like on Earth, reported the study. Interestingly, this was discovered by pure chance — something that's always a welcome surprise.
The first space spider experiment happened in 2008, when orb web spiders created totally symmetrical webs. However, these experiments went a little haywire as one of the two spiders escaped its habitat and moved across to another one, joining the second spider. Their webs became a tangled mess, making it too hard for the scientists to properly decipher what was going on. And to make matters worse, the fruit fly larvae used to feed the spiders got out of hand, and it was near impossible for the scientists to even see through the habitat's glass.
This is why, when a second chance to send spiders to space came up in 2011, the authors of the study jumped on the opportunity.
The two spiders were kept well separated in their own chambers, and two of the same type of spiders were kept in identical habitats on Earth, so as to draw comparisons.
The team observed the spiders over two months, using cameras that snapped images every five minutes. "We assessed the spider orientation in 100 webs based on 14,528 pictures, of which 14,021 showed the spider in its resting position and could therefore be used for the analysis," wrote the authors of the study.
Many webs were indeed more symmetrical in space than on Earth, however, a number of webs were asymmetrical when the 'building had started when the lights were on, suggesting that light replaced gravity as an orientation guide during web building," said the study.
It appears the lights offered the spiders a reference between up and down, helping them create their webs in a similar fashion. Golden silk orb weavers typically place the center of their webs near the top of them, and they themselves face downwards so that they can use gravity in their favor when rushing down to catch their prey.
"We wouldn’t have guessed that light would play a role in orienting the spiders in space," said Samuel Zschokke from the University of Basel in a statement. "We were very fortunate that the lamps were attached at the top of the chamber and not on various sides. Otherwise, we would not have been able to discover the effect of light on the symmetry of webs in zero gravity."
Take a look at the space spiders in action below: