Which crooning singer makes you weak in the knees? Music can play an important role when in seducing someone, and the 'purring' wolf spider seems to be no exception. New research shows that these spiders use leaves to create audible sounds to attract potential mates.
While spiders use vibrations to 'communicate,' they are not known for creating audible noises since they don’t have the structures needed to hear them, i.e. ears. Most spiders use their legs to ‘listen’ to vibrations in order to communicate with others and pick up information on nearby predators and prey. Researchers were therefore puzzled by reports of a quiet "chorus of spiders" from ecologists working in U.S. forests. They thus decided to investigate “whether this species [was] using airborne sound to communicate," co-author Alexander Sweger of the University of Cincinnati told BBC News.
To do this, the researchers captured the sounds these wolf spiders, Gladicosa glucosa, made on different surfaces during courting rituals. Once they detected the scents given off by females, male spiders dragged a specific structure, known as a stridulatory organ, across the surface they were perched on to create vibrations, which produced a sound. The team recorded this sound, or 'purring,' using a tiny recording studio. They then played back these airborne sounds, and not the physical vibrations, to female spiders.
The study, which was presented at the Acoustical Society of America annual meeting, found that the mating ritual only worked when both spiders were on structures that vibrated easily. Sweger told the Acoustical Society of America that “the leaves were vital” for acoustic communication. Sweger explains that the vibrations males make in one leaf creates a sound that travels to another leaf, which then creates a new vibration that the female can detect.
"On granite or wood or dirt, you get little to no vibration and almost no sound,” he said to BBC news.
When vibrations were removed and both females and males were exposed to an acoustic signal, researchers observed a response from females, but not males. Researchers therefore suggest these sounds may play a specific role in communication with females. This represents a ‘primitive’ form of acoustic communication that, according to researchers, could make the purring spider an ‘unusual’ model to understand the evolution of sound as a form of communication in animals.
