According to a study carried out on a species of spider, Larinioides sclopetarius, spiders could detect sounds through their web. According to the researchers, the webs would act as “external eardrums”.
Study results can be viewed on the BioRxiv preprint server even if the article has not yet gone through a peer review. According to these results, the webs of web spiders, by their wavy nature, act as an acoustic antenna for detecting sounds. But on top of that, they can also be considered to be one of the most effective “eardrums” in nature.
In humans, the eardrum is located between the outer ear and the inner ear. It is intended to collect sound vibrations and thus constitutes a determining element of the auditory system. Its dysfunction can lead to hearing loss. For invertebrates without eardrums, nature has endowed them with long thread-like structures that serve to detect airborne sounds.
The study was done on spider specimens Larinioides sclopetarius placed on a wooden frame where they spontaneously wove a web. The researchers filmed the spiders’ reactions to sounds coming from different distances and directions. The experiment found that the spiders changed posture even in response to sound from a relatively distant source, placed 3 m away.
The experiment also showed that the hearing threshold of the spiders studied was below 68 decibels. The researchers estimate that these spiders could be able to detect predators and prey at a distance of more than 10 meters. These indeed produce sounds above 80 dB.
A versatile material
If the result of this study is approved by the peer review, it could indicate that the spiders have managed to overcome the constraints imposed by their size to create an external eardrum whose surface can reach up to 10,000 times that of their body. The advantage of hearing thanks to a renewable and repairable fabric is also to be able to adjust this acoustic antenna according to needs.
Spider webs are thus more than traps for catching prey. In fact, as the researchers behind this study point out, biologists and materials scientists continue to find new properties of spider silk. This could be transformed into bio-material and be used in human applications.