MISSOULA - This edition of A Wilder View takes a look at why spiders can lead us to the next advancements in hearing aids.
Everyone knows that people and most wildlife can hear using eardrums. But what about smaller animals like insects and spiders? Can they detect sounds?
Most people are familiar with the fact that spiders respond to vibrations in their web when prey is caught. But new research is providing evidence that spiders are using their webs as a giant ear.
A newly published study published in the National Academy of Sciences focuses on a species of spiders called orb-weavers which are the same species featured in the classic children’s book “Charlotte’s Web.”
Spiders can detect tiny movements and vibrations through sensory organs located at the tips of their legs, which they use to grasp their webs. Orb-weaver spiders are known to make large webs, creating a kind of acoustic antennae with a sound-sensitive surface area that is up to 10,000 times greater than the spider itself.
Millions of years ago as animals emerged from water to land-dwelling creatures they underwent dramatic changes to hear on land. The auditory organs of these animals are extremely diverse in anatomy after hundreds of millions of years of evolution, yet all are attached to the bodies of animals.
Spiders are among the oldest land animals, with a fossil record going back around 380 million years ago. Unlike other fellow land animals, this research has produced the first evidence that a spider can outsource hearing to its web.
All spiders produce silk, a biomaterial that can be stronger than steel in strength-to-weight ratio yet extremely flexible.
A single strand of silk is so thin and sensitive that it can detect the movement of vibrating air particles that make up a soundwave, which is different from how eardrums work. These detections allow spiders to use their webs as extended abilities to hear. Perhaps using this as an alert of incoming prey or predators.
This gives scientists implications for designing extremely sensitive microphones for hearing aids and cell phones.
Scientists did this by placing a very small speaker 5 centimeters away from the center of the web where the spider sits, and 2 millimeters away from the web plane. Which is quite close, but not touching the web.
This allows the sound to travel to the spider both through the air and through the web. The soundwave from the small speaker fell out significantly as it traveled through the air, but it easily traveled through the web barely reducing the sound.
Researchers further found that spiders can pick up different sound frequencies. They do this by changing the tension on the silk strands through crouching or stretching. So a spider web can essentially be customized to hear specific sounds. Spiders will also change the direction and shape of their web to pick up noises.
We might not exactly be finding spider webs in our phones or hearing aids just yet. But this groundbreaking research shows the innovative ways we can discover mechanical advancements through our natural world.
