Silk is a catch-all term for a range of high-strength threads produced by invertebrates to build webs, nests, cocoons and egg-cases. But the process of making these threads is universal.
How is silk made?
It starts out as a gel-like fluid composed of short protein chains and only solidifies when it is extruded from glands via tiny nozzles. The forces involved in squeezing it out cause the protein chains to interlink, producing gossamer-thin threads.
Silkworm caterpillars pupate within a cocoon spun from a single thread hundreds of metres long. Textiles made from it are highly durable and, thanks to the microscopic structure of the fibres, scatter light to produce an attractive shimmering effect.
Main image: a silkworm works on a cocoon/Credit: Getty