The structure a spider builds to catch prey is called a web.
A web is made from protein-rich silk produced by glands in the spider’s abdomen and extruded through organs called spinnerets. Different spiders make different designs, including spiral orb webs, sheet webs, funnel webs, tubular webs, and tangled cobwebs. The familiar orb web uses radiating threads for support and sticky spiral threads to trap flying insects.
When prey strikes the web, vibrations travel through the silk and alert the spider. The spider then approaches, bites or wraps the prey, and may inject venom before feeding. Web-building can save energy compared with chasing prey, although producing silk requires substantial protein. Some spiders even eat and recycle their old webs.
A common mix-up is assuming every spider builds a web. Many species, including wolf spiders and trapdoor spiders, hunt without a conventional prey-catching web. “Cobweb” usually means an abandoned or dusty web, though biologists also use it for certain three-dimensional tangled webs. Spider webs have existed for at least 100 million years, based on fossilized examples in Early Cretaceous amber.