Why don't spiders stick to their webs?

Silk line with middle claw and bristles.

Spiders keep their bodies clear of web surfaces, especially those made with catching silk - they also have areas in their webs, like the hub of an orb web or the retreat funnel of a window spider's web, which lack catching silk. When moving about in the web, the spider has only a tiny area of its body in contact with the silk lines - the tips of its legs. For example, orb weavers clasp a silk line using only the middle claw and the adjacent toothed bristles on the leg tips. This small contact area, aided by regular cleaning of the leg tips (watch a spider drawing its legs through its jaws) and the probable secretory lubrication of the claws, combine to ensure that spiders don't stick to their webs.