A common type of spider has been discovered to have the ability to trap and subdue its prey using electrically charged silk webs. The spider, Uloboros plumipes, better known as the “garden center spider,” can create exceptionally durable silk fibers which can harbor an electric charge. These nanometer-thick strands of electrically charged silk are then used to capture what the spider needs for sustenance. Scientists at Oxford University in England have found that these types of spiders, also known as the “feather-legged lace weavers” are commonly found in Britain.
Researchers discovered that these spiders possess an organ that is not normally found in other types of spiders. The organ in question is called the cribellar. The cribellar is composed of two plates that hold silk faucets with a very small diameter – 50 nanometers. These faucets create unbelievably strong filaments. More importantly, these filaments do not rely on sticky, dense masses of webbing, but instead are very dry and have thousands of nano-sized strands which contain an electrical charge, creating “puffed-up” capture filaments.
Katrin Kronenberger, a zoologist at Oxford University, stated that Uloboros plumipes has novel cribellar glands which are nearly the tiniest silk glands of any spiders discovered. She further explained that the glands yield the nano-sized “catching wool” to capture and harvest its prey.
On Jan. 28, an issue of the journal Current Biology contained a paper regarding the discovery of the common spider’s ability to create its unique web. First, the spider secretes a liquid from its silk glands, or cribellar glands. The spider then pulls the silk over what is described as a “comb-like plate” within the spider. The silk then begins to dry and solidify.
This plate is located around the hind legs of the spider. It is responsible for generating the electrostatic charge that swells the filaments.
Initially, the Oxford researchers started their experiments by gathering female spiders from the South of England. They then recorded and measured the way in which the spiders spun their webs. By utilizing sophisticated high-definition cameras, the research team was also able to look at the spider’s cribellar gland – the aforementioned silk-creating organ.
The research team stated that they were awestruck by the sighting of the cribellar, which is rarely seen in any other type of spider, but does vary from spider to spider. They can possess one or two plates and a vast and varying number of nano-sized silk faucets.
The process of using the comb-like plate to weave the strands of silk creates an electrostatic charge because of the vigorous movement involved. Since the filaments are so thin, when combined with the electrostatic charge they have, the “sticky” threads create a Van der Waals force that traps the prey of the spider.
The Van der Waals force is attributed to an electrostatic interaction with charged ions that allows for covalent bonds to form, which allows for the creation of a sticking force. Geckos also use this technique to climb vertical surfaces without losing grip and falling.
It is very possible that in the future, scientists could use the spider’s method and ability to create electrically charged filaments to further studies about carbon nano tubules. Even though it is only used for trapping prey, studying this electrically charged spider may provide knowledge which could pave the way for very durable and versatile polymer processing technology in the future.
By: Alex Lemieux
Picture: Cletus Lee – Flickr License