If you are one of the many people who have a fear of spiders, you may want to stop reading now. Or at the very least, you may want to make sure you are not reading this aloud, because they might be listening.
In a recent discovery that is sure to dismay many, scientists have found that spiders can hear you from across a room. What makes this even more remarkable, is that they don’t actually have any ears. What they use instead, is their hairy legs.
It had been believed that the tiny hairs on spiders’ legs were only receptive to vibrations arriving through air or solid objects from a few centimetres away. But new research has now shown that their senses are far more acute, and allows them to hear sounds from up to 5 metres away.
Paul Shamble, who led the research at Cornell University in Ithaca, New York, says that the findings are exciting as it upends the belief that spiders rely mainly on sight and touch to navigate the world around them.
Shamble and his colleagues made the discovery partly by chance. They had set out to study how a type of jumping spider, Phidippus audax, processes visual information, only for the sound of a moving chair to change the direction of their research.
The team was using microelectrodes implanted in the spiders’ brains to monitor neuron activity when they noticed that the spiders were responding to the sounds of scraping chairs from several metres away.
To even obtain these electrical recordings was quite an achievement. Previously, any attempt to drill a hole into a spider to record brain activity had caused the creature to explode. This is because spiders are filled with highly pressurised liquids that allow their bodies to function like a hydraulic system.
Whilst the thought of exploding spiders may fill many arachnophobes with glee, it would not of been an efficient means of study for the research team.
To prevent this messy end, a tiny hole was made in the spiders’ heads and allowed to self-heal around an electrode as thin as a hair. The researchers could then observe the workings of a brain the size of a poppy seed.
This revealed that the spiders were most responsive to low-frequency sounds of around 80 to 400 hertz, which is about the pitch of a deep male voice. This corresponds with the wingbeat frequency of parasitoid wasps and flies that prey on the jumping spider.
The deformations on the tiny hairs that register the sounds are found on all spiders, so researchers believe it will be a common trait.
Having already begun testing on other species, Shamble’s colleague, Gill Menda has even tried the experiment outside of the laboratory. “When I see spiders at my house or anywhere else, I find myself trying different tones to see if they respond, and sometimes they do.”
Why not try the experiment at home? There’s probably no better time to try and communicate with spiders than Halloween.