Spider Purrs Like a Cat to Sound Sexy
Sleek and graceful, frisky and mischievous - humans have long drawn obvious parallels between feline characteristics and 'sexy' behavior. Now, researchers have determined that one species of spider may have also taken some cues from the kitty-cat playbook, apparently purring like pleased Persians in order to attract a mate.
That's at least according to a study published in The Journal of the Acoustical Society of America, which details how George Uetz and Alexander Sweger of the University of Cincinnati discovered a new species of wolf spider (Gladicosa gulosa) with audible mating songs that sound a lot like a cat purr.
Nature World News is no stranger to spider sex life. We've published many articles that detail how strange and downright disturbing arachnid mating can be. However, this is the first time that we've encountered strong scientific evidence that male spiders can attract a mate using audible sounds like a bird or frog would.
But it isn't just us. Last week, when Uetz and Sweger presented their findings at the annual meeting of the Acoustical Society of America in Pittsburgh, Pennsylvania, they admitted that this came as a huge surprise.
"While a lot of species that use vibration will simultaneously use airborne sound, spiders do not possess structures for hearing sound, and it is generally assumed that they do not use acoustic communication in conjunction with vibration," the Sweger explained. "The 'purring' wolf spider (Gladicosa gulosa) may be a unique exception to this assumption."
To be clear, it not uncommon for wolf spiders to use vibrations to communicate. While spiders often convey obvious messages like "I'm looking for a mate," or even "I'm hungry and will probably eat you," through chemical pheromones, vibrations called 'send signals' also help establish things like aggression or sexual advances.
Wolf spiders are one group that heavily relies on these signals, boasting specialized structures on their legs that help them detect subtle vibrations in the surface they stand on. (Scroll to read on...)
A purring song, however, is completely different. [Visit here to listen to the spider's 'song.']
"It's very quiet, but it's what you would hear if you were in the room with a courting spider," Uetz recently said in New Scientist's popular Zoologger blog. "The sound is at a level that's audible by human hearing at about a meter away."
And what's unusual about that is that despite their sensitivity to vibrations, spiders have no ears. Vibrations in the air, that purring sound G. gulosa makes, would normally remain undetectable.
And yet, "when we remove the vibration and only provide the acoustic signal, females still show a significant response and males do not," Sweger explained during their presentation.
So what's going on here? How is it that the females are hearing the purr?
Moving these cat-like spiders to a controlled setting, the researcher quickly learned that both male and female have to be standing on similar surfaces for a spider-song to be heard. In fact, it's this surface that the male uses to make the sound in the first place, essentially drumming out a soft-but-fast beat. (Scroll to read on...)
"Despite the relatively low volume of the sounds produced, they can still create a vibration in a very thin surface like a leaf," Swegar said. "This creates a complex method of communication- a male makes a vibration in a leaf that creates a sound, which then travels to another leaf and creates a new vibration, which a female can then hear."
In this way, the purring spider has taken traditional send signals and made them long distance. Gone are the days when spiders had to stand on the same leaf to patter out their Morse code. The purring wolf spider has gone 'wireless!'
And you should take notes gentleman, because this ingenious strategy for chatting up a lady seems to get the girl. The purring spider, with his clever song, can arguably travel less, not having to climb from surface to surface looking for a mate. Instead, he sits on a stage and waits for the fans to flock.
Swegar and Uetz added that this is also a promising discovery for evolutionary theory - a hint that audible communication among creatures may have originated from vibrations alone. That however, remains purely speculation.
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