Most spiders wait for insects to wander into their webs. Some spiders instead fling their webs at prey. Called net-casting spiders, they need extra-sturdy webs. Now, a close look at the silk of one net-casting spider has revealed the secret to that strength.
Scientists used a scanning electron microscope to peer at the webs of rufous net-casting spiders (Asianopis subrufa). Looping strands surround a stretchy silk core, these images showed. This allows the spiders’ silk to stretch a long way without snapping.
Researchers shared these findings on February 3. Their work appeared in Proceedings of the National Academy of Sciences.
Watch a net-casting spider launch its web at a grasshopper, dramatically stretching the silk fibers in the process.J.O. Wolff et al/PNAS 2026A net-casting spider in search of a meal first dangles upside down, holding a web in its legs. Then, it launches itself at an unsuspecting insect. In the process, parts of the web can stretch to up to 24 times their original size — and in only about a tenth of a second.
For most materials, there’s a tradeoff between stretchiness and strength. Substances that stretch a lot tend to break more easily. But the webs of net-casting spiders manage to be both strong and stretchy.
As a strand lengthens, the loops straighten. Those threads reinforce the core to keep it from breaking. The spiders adjust the amount of coiling in different sections of the web depending on how much each portion needs to stretch.
These net-casting spiders produce their loops of silk from a different set of glands than the core fiber. The result is a sturdy material that is beautiful — but deadly.
Bengali (Bangladesh) · 
English (United States) ·