How Good Are Spiders Hearing?
WouterThere’s a lot we know about spiders’ senses, but a new study by Cornell University shows they have a unique way of hearing far away. These spiders, known as jumping spiders, are able to hear sounds up to five metres away.
Researchers have long thought that spiders’ acoustic organs would pick up vibrations in their web, but they were surprised when they discovered the creatures actually reacted to sounds from a distance. They’re also sensitive to the airflow around their body, which could explain why they were able to detect the movements of airborne sound waves.
To test their ability to hear, researchers placed a mini speaker in a spider’s web, about two millimeters away from the spider’s plane. The speaker emitted a soundwave, which traveled easily through the web. The signal was 68 decibels when it reached the spider. The researchers then played a variety of sounds at different times and angles to see whether the spiders reacted.
After testing, researchers found that four out of 12 spiders responded to the web-borne signal. The spiders reacted with an alarm. This response is called the startle response. It’s possible that these spiders listened for the sound to be coming from a predator. The researchers are planning to continue their studies, examining other noises and angles of sound.
The research was supported by the National Science Foundation. The Stafstrom team plans to place a spider in an arena to test the spiders’ ability to discern the direction of a sound.
