Researchers Discover Why Spiders Don't Stick to Their Own Webs
Posted on March 1, 2012
Researchers at the Smithsonian Tropical Research Institute and University of Costa Rica have discovered why spiders don't stick to their own webs. Their results are published online in the journal, Naturwissenschaften.
There are two reasons why spiders don't get stuck on the very webs they spin. The spider's legs are protected by a covering of branching hairs and by a non-stick chemical coating. The spiders also use fancy footwork to avoid getting caught in their webs.
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 helped to determine that individual droplets of sticky glue slide along the leg's bristly hair. By washing spider legs with hexane and water, the researchers found that spiders' legs adhered more tenaciously when this non-stick coating was removed. You can see a video here that shows how the pointed drip tip of the bristly hairs on a spider's leg helps any adhesive from the web that sticks to its leg drip back off.
The researchers 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 orb. A slow-motion video of a spider adeptly handling its sticky silk here.
Reference: R.D. Briceno 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.