Spiders use silk to create webs and capture prey. This protein fiber is produced by specialized glands and released through structures called spinnerets, usually located at the end of the abdomen.
Spider silk is not a single uniform material. Different glands produce silks with different properties: strong dragline silk can form the web’s outer frame and spokes, while stretchy capture-spiral silk is coated with sticky droplets that help trap flying insects. Other silk can wrap prey, protect eggs, build shelters, or provide a safety line.
Web-building spiders often detect a trapped insect through vibrations traveling along the threads. They can move across selected non-sticky strands while avoiding the adhesive capture lines. Oils, dense hairs, and careful foot placement also help prevent the spider from becoming caught in its own web.
Not every spider uses a large web to hunt. Wolf spiders actively chase prey, while bolas spiders use a single sticky silk line as a lasso-like trap. Thus silk is the canonical answer, even though spiders use it for many purposes beyond conventional webs.