Why spiders are so good at browsing the web

Spiderwebs are notoriously sticky yet spiders are able to move easily around their webs. What keeps them from sticking? Researchers at the Smithsonian Tropical Research Institute and University of Costa Rica replicated several old, widely cited but poorly documented studies using  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.

G. cancriformis, the crab spider

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

The web-weaving behavior of two tropical species, Nephila clavipes and Gasteracantha cancriformis, was recorded with a video camera equipped with close-up lenses. Another video camera coupled with a dissecting microscope allowed the researchers to to estimate the forces of adhesion to the web and to observe how individual droplets of sticky glue slide along the legs’ bristly hair. After removing the non-stick coating by washing spider legs with hexane and water, they showed that spiders’ legs adhered more tenaciously to the web.

Reference: 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.

Image via Flikr user Cheron

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