Jumping Spiders Can ‘Hear' Using Their Leg Hairs

Spidey senses are tingling (literally).

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Oct 14 2016, 6:28pm

Image: Cell Video Abstracts/Youtube

Jumping spiders can hear what you're up to from across the room, much to the surprise of researchers, as the spiders lack ears or ear-like structures. However, new findings discovered by accident and published recently in the journal Current Biology show the spiders can pick up on sounds coming from really far away.

Until now, scientists didn't think these spiders (Phidippus audax) could hear or perceive much in the way of auditory sensation. They gather much of the information they need to survive through those googly eyes (jumping spiders have four pairs). So, originally, the scientists wanted to study more about that spidey sensory experience.

"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.

So, feel free to whisper soothing, sweet nothings to the jumping spiders in your life today.

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