It’s summertime and that means there are lots of spiders crawling around and building their sticky webs. Spiders use their webs to capture food. If a small insect wanders into the web it quickly becomes stuck and ends up being a nice meal for the spider. However, it now appears that static electricity may play a significant role in how a web captures insects.
If you have ever shuffled your feet on a carpet and received a little shock when you touched a doorknob, then you are familiar with static electricity. Rubbing two objects together can cause both of them to build up an excess of non-moving, or static, electric charge. This can happen even to very small creatures. When an insect is flying, its wings “rub” against the surrounding air molecules which results in the insect itself becoming electrically charged.
So how does this relate to spiderwebs? New research published by scientists at the University of California at Berkeley, now suggests that electrically-charged insects can attract and deform certain types of spider silk. As reported in the open-source, online journal Scientific Reports, authors Victor Manuel Ortega-Jimenez and Robert Dudley found that when electrically-charged insects, such as honeybees and fruit flies, passed near the web of a cross spider, the web became attracted to the insect and would actually move towards it. Depending on the size of the insect and the electric charge it carried, the web could move up to 2 millimetres. In other words, using electrostatic attraction, it may be possible that a spider’s web could “reach out” towards an insect and capture it rather than just waiting for the insect to fly into it. In addition, this electrostatic attraction would also increase the “stickiness” of the web and would help keep the insect trapped until the spider could get to it.
So, the same phenomenon that makes your socks stick to your pants when they come out of the dryer can actually help web spiders capture their prey. Quick, someone get that honeybee a sheet of Bounce!
At TELUS World of Science you can learn more about spiders by visiting the Search: Sara Stern Gallery (make sure to say hi to Ruby the tarantula!).
To learn more about static electricity, check out our Electricity Show which is performed on the Peter Brown Family Centre Stage.
The original research paper, “Spiderweb deformation induced by electrostatically charged insects,”can be read for free at Scientific Reports.
A nice non-technical summary of the work (and some more information from the authors) can be found at Sciencemag.org.