Washington: A team of researchers have found that male black widow spiders shake their abdomens to produce carefully pitched vibrations, which let females know they have "come a-courting" and are not potential prey.
Simon Fraser University graduate students Samantha Vibert and Catherine Scott , working with SFU biology professor Gerhard Gries, recorded the vibrations made by male black widow spiders (Latrodectus hesperus), hobo spiders (Tegenaria agrestis) and prey insects.
Scott explained that 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.
She said that 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 found that 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.
Scott explained that these `whispers` may help to avoid potential attacks from the females they are wooing.
The research has been published in the journal Frontiers in Zoology.