Why spiders do not stick to their own sticky web sites

Why spiders do not stick to their own sticky web sites
This mature female Golden Silk Spider had just contacted the sticky line with her right leg IV and was about to extend this leg, thereby pulling additional line from her spinnerets. Credit: C. Frank Starmer Source: http://commons.wikimedia.org/wiki/File:Oct_03_nephila_weaving.jpg. This file is licensed under the Creative Commons Attribution-Share Alike 2.5 Generic license.

Researchers at the Smithsonian Tropical Research Institute and University of Costa Rica asked why spiders do not stick to their own sticky webs. Repeating old, widely quoted but poorly documented studies with modern equipment and techniques, they discovered that spiders' legs are protected by a covering of branching hairs and by a non-stick chemical coating.

Their results are published online in the journal, Naturwissenschaften.

They also observed that carefully move their legs in ways that minimize as they push against their sticky silk lines hundreds to thousands of times during the construction of each orb.

In this video of Nephila clavipes building a web, you can clearly see the pointed drip tip of the bristly hairs on the spider's leg. Tropical plants have leaves with pointed drip tips so that water drains off of them easily. In this case, any adhesive from the web that sticks to the spider's leg readily drips off. Credit: Daniel Briceno

The web-weaving behavior of two , Nephila clavipes and Gasteracantha cancriformis, was recorded with a video camera equipped with close-up lenses. Another video camera coupled with a dissecting microscope helped to determine that individual droplets of sticky glue slide along the leg's bristly hair, and to estimate the forces of adhesion to the web. By washing spider legs with hexane and water, they showed that spiders' legs adhered more tenaciously when the non-stick coating was removed.

Researchers slow down video images in order to carefully observe how a spider (Gasteracantha) handles the sticky silk that it uses to trap its prey, pulling the silk out of its abdomen with its fourth leg and stretching it to weave its web. Credit: Daniel Briceno

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More information: R.D. Briceño and W.G. Eberhard. 2012. Spiders avoid sticking to their webs: clever leg movements, branched drip-tip setae, and anti-adhesive surfaces. Naturwissenshaften. DOI 10.1007/s00114-012-0901-9 . Published online: 1 March 2012.
Provided by Smithsonian Tropical Research Institute
Citation: Why spiders do not stick to their own sticky web sites (2012, March 1) retrieved 25 May 2020 from https://phys.org/news/2012-03-spiders-sticky-web-sites.html
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