Spiders carefully move their legs

Why Spiders Do Not Stick to Their Own Sticky Web Sites

                                              Photo Courtesy:InfoVisual

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 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.   
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, 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. 
The Smithsonian Tropical Research Institute, headquartered in Panama City, Panama, is a unit 
of the Smithsonian Institution. The Institute furthers the understanding of tropical nature and its 
importance to human welfare, trains students to conduct research in the tropics and promotes 
conservation by increasing public awareness of the beauty and importance of tropical ecosystems. 
Website: www.stri.si.edu.  

Spiders carefully move their legs
The web-weaving behavior 
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