In a recent episode of Science Friday, host Flora Lichtman spoke with scientist William Eberhard of the Smithsonian Tropical Research Institute to try to find the answer to the long-running question of why spiders don’t stick to their own webs. After long and careful research, Eberhard and his research colleague Daniel Briceño determined that the spiders employ extremely delicate movements using a naturally greasy part of their hairy legs, all of which reduce adhesion.
The way they touch these lines is very stereotyped and and very careful in the sense that it’s
always the same part, the same portion of the same leg that make this contact and if you look at that part of the limb, the tarsus under a microscope you see these, what most people call hairs. It’s like a grip tip on a leaf of tropical plants, the last point of contact is very small as a spider’s pulling away and so the strength of the adhesions is relatively weak. Less surface area for the glue to stick to and the last factor is that spiders do in fact have a coating which then even reduces adhesion even farther.