Just call it Good Vibrations.
A team of biologists at Simon Fraser University in B.C. says male black widow spiders shake their abdomens to produce carefully pitched vibrations that let females know they fancy them.
Their research has just been published in the open access journal Frontiers in Zoology.
Graduate students Samantha Vibert and Catherine Scott recorded the vibrations made by male black widow spiders , hobo spiders and prey insects.
“The web functions as an extension of the spider's exquisitely tuned sensory system, allowing her to very quickly detect and respond to prey coming into contact with her silk," Scott said on the school's site. “This presents prospective mates with a real challenge when they first arrive at a female's web: they need to signal their presence and desirability, without triggering the female's predatory response.”
The researchers say the courtship vibrations of both species differed from those of prey, but that the very low-amplitude vibratory signals produced when male black widows shake their abdomens were particularly distinctive.
“These 'whispers' may help to avoid potential attacks from the females they are wooing," explains Scott.