Scientists have discovered a remarkable property of a certain type of spider silk: It acts like a solid when you stretch it, but liquid when you squish it. And they've proven that they understand how this "liquid wire" works by actually creating synthetic strands that can do the exact same thing -- solving a decades-old mystery in the process. The findings, described in the Proceedings of the National Academy of Sciences, reveal the bizarre phenomenon that may help spider webs remain taut, and could offer fresh insight for a range of technologies, including soft robotics. Spiders spin a range of web shapes, from funnels to nests, but the classic orb-like structures remain something of an archetype. Such webs typically have sticky droplets of glue on the strands of capture thread – the segments of spider silk that connect the radiating branches of these disc-like webs.

Spider silk has long been hailed for its wondrous properties, such as incredible toughness. Now researchers have found a weird kind of webbing that acts as both a liquid and a solid. What's more, they've created an artificial version that could find use in soft robotics. Arnaud Antkowiak of the Pierre and Marie Curie University in Paris, France, and his colleagues studied the "capture silk" of an orb-weaver spider – the sticky silk that makes up the spiral of a spider's web, rather than the radial spokes that hold it together. When they stretched the silk, they found it extended like a spring, just as you would expect from a solid material.