Uloborus Spider Spins Nanometer Thin Electrically Charged Webs

Posted on January 29, 2015

A species of garden spider, Uloborus plumipes, is capable of spinning nano-scale filaments. The spider also builds up an electrostatic charge on these threads that are just a few nanometers thick. This helps make the web stickier and more difficult for prey to escape.

Researchers from Oxford University have been studying the spider, which is also known as the feather-legged lace weaver. They say the spider uses dry capture threads made up of thousands of nano-scale filaments to capture prey in electrically charged wool-like puffs. The researchers found that the spider has a unique cribellum - a spinning organ - covered with thousands of tiny silk-producing units. The silk-producing ducts average 500 nanometers in length. The ducts contain spigots with a diameter of about 50 nanometers.

Dr Katrin Kronenberger of Oxford University's Department of Zoology, says in a statement, "Uloborus has unique cribellar glands, amongst the smallest silk glands of any spider, and it's these that yield the ultra-fine 'catching wool' of its prey capture thread. The raw material, silk dope, is funnelled through exceptionally narrow and long ducts into tiny spinning nozzles or spigots. Importantly, the silk seems to form only just before it emerges at the uniquely-shaped spigots of this spider."

Fritz Vollrath of Oxford University's Department of Zoology says the capture threads become electrically charged through the spiders combing and hacking of the silk fibers. He says, "The swathe of gossamer, made of thousands of filaments, emerging from these spigots is actively combed out by the spider onto the capture thread's core fibres using specialist hairs on its hind legs. This combing and hackling - violently pulling the thread - charges the fibres and the electrostatic interaction of this combination spinning process leads to regularly spaced, wool-like 'puffs' covering the capture threads. The extreme thinness of each filament, in addition to the charges applied during spinning, provides Van der Waals adhesion. And this makes these puffs immensely sticky."

The image below shows the capture thread of Uloborus its characteristic "puffs." The image was taken using a Scanning Electron Microscope. A research paper on the spider's unique nano-scale spinning technique was published here in the journal, Biology Letters.

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