Spiders make silk in a variety of ways. Some species pounce on prey, others wrap prey in silk, and others use it to build webs.
Silk is a protein fiber made by spiders. It is a thick, elastic material that is about five to six times stronger than steel by weight. Moreover, it is very flexible. In fact, it can stretch up to four times its original length.
Spiders make silk from proteins that are stored in their glands. The spigots of each spinneret connect to the spider’s silk glands. Each spinneret produces a single thread, but can move independently. When the silk is spun, the spinnerets align the proteins into a solid fiber.
Unlike human-made threads, which are unable to hold up to the force of spider-spun threads, spider silk is exceptionally tough. So much so that it has been used as a safety line for escaping predators. As such, it is an important natural biomaterial.
However, scientists have tried to reproduce silk in the laboratory and failed. They are still trying to figure out why spiders spin silk better than humans do.
One theory is that the silk is spun from nanoparticles. These particles may produce tougher fibers. Another theory is that it is a glue-like substance that coats the silk threads.
Regardless of the hypothesis, researchers believe that silk is one of the most versatile natural materials on Earth. For example, water spiders use silk to hold underwater air supply.