Space Station Spiders Found a Hack to Build Webs Without Gravity
upstart writes in with an IRC submission:
Space Station Spiders Found A Hack To Build Webs Without Gravity:
Under normal gravity conditions, orb web spiders tend to build asymmetrical webs with the center, or hub, positioned toward the upper edge. When resting and waiting for prey, spiders sit in their hub with their heads facing downward, allowing them to quickly pounce on their prey in the direction of gravity.
[...] The chosen species for the 2011 spider experiment is the golden silk orb weaver, or Trichonephila clavipes. [...] two spiders would build their webs in separate testing chambers on the ISS, while two spiders were kept in identical habitats on the ground to serve as the control group.
[...] It turns out that the spiders, when working in microgravity, tend to weave webs that are discernibly more symmetrical than those built on Earth. Also, the hubs were positioned closer to the center of the webs, and the spiders didn't always keep their heads in a downward position.
But this wasn't the case across the board. Some webs exhibited a surprising degree of asymmetry, especially for those "whose building had started when the lights were on, suggesting that light replaced gravity as an orientation guide during web building," according to the paper. Moreover, the light also provided a reference for the spider in terms of positioning themselves atop the web (by top, the researchers are referring to the top of the habitat ).
Funny thing is, access to a light source was not even considered as a factor going into the experiment.
Journal Reference:
Samuel Zschokke, Stefanie Countryman, Paula E. Cushing. Spiders in space-orb-web-related behaviour in zero gravity [open], The Science of Nature (DOI: 10.1007/s00114-020-01708-8)
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