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Monday, July 4, 2011

Tarantulas shoot silk from their feet


Update 3/12: Apparently this finding is under dispute.
Update 5/13: And now, it appears to be completely falsified. Oh well.

Stan Lee may have been more right than he thought when he created Spiderman. According to Claire Rind and her colleagues from Newcastle University, tarantulas can shoot silk from their feet.

This spidey-ability has been suggested and discounted before. Tarantulas are very large spiders that have difficulty climbing and adhering to vertical surfaces. They are also surprisingly delicate and can easily be killed by falling. For this reason, Stanislav Gorb first proposed that tarantulas maintain their holds using silk secreted from their feet. However, no one had seen any traces of that foot silk.

This time, Rind placed a Chilean rose tarantula (Grammostola rosea) on a glass slide and carefully tilted it. The spider was able to cling to the surface even during gentle shaking. Consequent examination of the glass showed minute silk threads where the spider had been attached. Those threads were only visible under a microscope. Video clips of the spiders showed that the silk was only produced when the spiders slipped, and only when the feet were in contact with the glass.

The researchers next examined spider exoskeletons and found evidence of both tiny silk-producing spigots and of microscopic silk threads between the hairs of the spiders’ feet. Subsequent examination of two other tarantula species, the Indian ornamental (Poecilotheria regalis) and the Mexican flame knee (Brachypelma auratum), showed the same thing. This led the authors to suggest that all tarantulas have the ability to secrete silk from their feet, something they have in common with Spiderman.