Spider webs shake when fresh prey gets tangled in their threads. But the vibrations of spider silk can carry more than one message, and those messages can be subtle. In a recent study, researchers in the Oxford Silk Group took a careful look at how silk threads vibrate. According to Nautilus:
[T]he researchers got spiders to excrete single threads of silk, stretched them taut, and bombarded them with sound waves and even plastic bullets.
Using high speed cameras they observed that the silk transmits a wide range of vibrations, and that these waves can mean different things. Longitudinal waves, compression waves that flow down the length of the thread, for example, might typically signal that there is new prey in the net, while transverse waves, which make the thread move side-to-side, might signal damage. The scientists found that spider silk transmits a wider range of longitudinal waves than any other known material. Spiders, it seems, take advantage of the versatility of their silk to send messages, in addition to picking up on fresh prey and web damage.
"Because spiders have eight legs, they essentially have an ear covering all different directions," Beth Mortimer, the lead author of the study told National Geographic.
They also have a lot of control over the properties of their webs. According to Nautilus:
Spiders determine the thread’s properties with the way they spin it, and then pull it to any tautness they desire. And when spider silk gets damp overnight, it contracts, providing a kind of daily reset button that lets spiders re-stretch it to their liking the next day.
Spider silk is tough, lightweight and disposable, making it ideal for a range of medical and textile applications. Understanding the communicative properties of spider silk could reveal its additional use in "stimuli-responsive smart materials." That could happen soon. As Chemical & Engineering News reported earlier this year, spider silk could be on the market by the end of 2015.