Spiders "tune" their webs to react to a broad range of frequencies that can tell the arachnids a lot about prey or prospective mates or even alert them to the structural soundness of the web, British researchers say.
Scientists at three British universities collaborated on a study that saw lasers and bullets being fired at spider webs to see how they vibrate.
High-speed cameras filmed the vibrations caused by the bullets, while lasers created detailed records of even the tiniest vibrations.
The researchers said they were just doing what spiders do routinely -- using the webs to gather information.
Spiders will "pluck" the strands of their webs to generate their own vibrations, the researchers found, sending them out in all directions and receiving feedback through their eight legs.
"They generate these vibrations to get information," lead study author Beth Mortimer from Oxford University, said. "Because spiders have eight legs, they essentially have an ear covering all different directions."
They need to depend on such tactile information because they have extremely poor vision, she said.
"The sound of silk can tell them what type of meal is entangled in their net and about the intentions and quality of a prospective mate," she said. "By plucking the silk like a guitar string and listening to the 'echoes' the spider can also assess the condition of its web."
The different kinds of information a web can reveal is down to the fact that spider silk can be "tuned" as it is spun, with the spiders able to adjust and control its inherent properties and also custom-tune the interconnections and tensions in the web's design, the researchers reported in the journal Advanced Materials.
Spider webs could be a source of inspiration for human engineers, the scientists said, in their combination of toughness and the ability to transmit information.
Scientists have long been impressed by spider silk's combination of flexibility and strength, a combination difficult to achieve in most man-made materials.
Such traits could be useful in engineering new actuators and sensors with "built-in" intelligence, the researchers said, just one more secret gleaned from studying spiders and their webs.
"Spider silks are well known for their impressive mechanical properties, but the vibrational properties have been relatively overlooked and now we find that they are also an awesome communication tool," University of Sheffield researchers Chris Holland said. "Yet again spiders continue to impress us in more ways than we can imagine."
