Spiders typically produce sticky silks that are micrometers thick but the feather-legged lace weaver (Uloborus plumipes) is unique that it produces long, fluffy and charged wool-like silk that are only a few nanometers thick to catch its prey.
Now, two researchers have revealed that they have found how this process is done and detailed this in a study published in Biology Letters on Jan. 28. The findings could potentially pave way for technologies that would make commercial spinning of nano-scale filaments a possibility.
Katrin Kronenberger and Fritz Vollrath, both from the University of Oxfords' Department of Zoology, took photos and videos of adult female Uloborus spiders spinning their silk. The researchers used microscopy techniques in order to examine the organs that the spiders use to make their filaments.
The researchers found that unlike other spiders, the Uloborus uses an ancient spinning organ, the cribellum, which is made up of two plates that are thickly covered with silk-outflow spigots, which serve as the exit point for 500-nanometer long tubes that carry the silk raw material.
The researchers likewise found that the silk that comes out of the spider is liquid and as the Uloborus pulls on the silk, it transforms into a solid thread.
"The raw material, silk dope, is funnelled through exceptionally narrow and long ducts into tiny spinning nozzles or spigots," Kronenberger said. "Importantly, the silk seems to form only just before it emerges at the uniquely-shaped spigots of this spider."
The researchers said that a special combing action made by the spider along with a violent pulling of the threads produces an electrostatic charge, which when coupled with the thinness of the filaments that emerge from the spigots, provides adhesion and thus create a very sticky silk for prey capture.
"Uloborus is able to spin nano-scale filaments of great length and it may be assumed that the animal also somehow manages to electrostatically charge them," the researchers wrote. "The spinning system observed has key features not found in other spiders studied so far and clearly presents a challenge that needs to be tackled in detailed follow-up studies."
Kronenberger and Vollrath said that studying the spider provided them with valuable insights on how to create nano-scale filaments. They said that once the Uloborus' trick of electro-spinning nano-fibers could be reproduced, it could lead to an efficient and very versatile polymer processing technology.
