Lacking any ears like many other spider species, jumping spiders were once thought only to be able to feel vibrations from sound waves traveling through the air no more than just a few centimeters away or closer.
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But new research discussed in Current Biology suggests that jumping spiders may be able to feel these airborne vibrations several meters away thanks to very sensitive hairs on their legs.
These findings were stumbled upon completely by accident by Cornell and Harvard University’s Paul Shamble and his colleagues.
The team had implanted special electrodes into the jumping spider’s brain under a microscope, something that hasn’t been done before, and listened for neurons firing while testing the spider’s visual sensitivity.
When one of the researchers rolled away in his chair, he’d noticed that the neurons fired, suggesting the spider could hear, or more realistically ‘feel,’ the vibrations of sound in the air even when the action was taking place more than a few centimeters away.
The team then went and clapped their hands from a distance, and the neurons were found firing even then, confirming what they had thought they found.
"The sensory world of the tiny jumping spider was thought to be dominated by sight and tactile touch," says lead researcher Paul Shamble. "Surprisingly, we found that they also possess an acute sense of hearing. They can hear sounds at distances much farther away than previously thought, even though they lack ears with the eardrums typical of most animals with long-distance hearing."
Jumping spiders probably aren’t the only species to perform this sensory feature, as multiple different spider species may have the same mechanisms for sensing sound where ears and hearing aren’t exactly their best sense. Most rely on sight for everyday life.
The frequencies that spiders can hear from this innate ability is equally as interesting, as they’re about to hear the same frequencies you could expect from the wingbeats of wasps, which are spiders’ arch rivals in the animal kingdom. Such may permit them to hide from predators.
More research will now be conducted in other species of spiders to see whether or not the same kind of brain activity is present.