Despite the fact that they have no ear drums, the eight-legged creepy-crawlies can hear you “walking and talking” from more than 10 feet away, new research has found.
The research was conducted by scientists at Cornell University and was published in Current Biology October 13. The scientists found that spiders, specifically the jumping spider, can perceive and respond to airborne acoustic stimuli, even at relatively great distances. It was previously believed that they could only sense vibrations in the air from a few centimeters away.
“We wanted to study what the nerve cells in their brain were doing, and in order to that, we had to do something new,” said Ronald Hoy, professor of neurobiology and behavior at Cornell University, in a video posted to YouTube by Cell Press:
The “something new” was to make recordings of the spiders’ reactions to visual information, which they accomplished by drilling a small hole into the top of several spider subjects’ teensy-tiny heads, and implanting metal micro-electrodes directly into the arachnids’ brains.
While they were watching the spider’s neurons jump around in reaction to visuals, the researchers noticed something strange: whenever they got up and scooted their chairs around the laboratory, some of the neurons in the spiders’ brains reacted to these sounds alone. The spiders even reacted to noises from distances of 10 to 16 feet (3-5 meters) away, as Research Gate reports.
As it turns out, the spiders pick up frequencies around 80 to 130 Hz, right in range for their chief predators: wasps. The spiders are “listening”, or picking up auditory information, with the long hairs on their legs called trichobothria. This previously unknown capability helps them stay on the lookout for their enemies in the wild.
The researchers note this may also help explain the spiders’ courtship dances (which involve “rapid leg movement”) and could be used to help further understand how other species of spiders are able to navigate the world, even when they are on vibration-dampening surfaces.