Auditory sensing can be achieved by spiders using webs as external eardrums

Washington DC: Orb-weaving spiders use their webs as external eardrums to outsource auditory detection, according to a study led by Binghamton University researchers. The study, “Outsourced hearing in an orb-weaving spider that uses its web as an auditory sensor,” published in the journal PNAS, looks at how terrestrial animals have evolved a range of auditory organs that are bound by body size.

Ronald Miles, Ronald Hoy, Jian Zhou, and colleagues explored the ability of (Larinioides sclopetarius) to detect and localize distant airborne sound using their webs. The authors exposed 72 spiders in sealed lab chambers to acoustic tones emitted at various distances from and angles to the webs and videotaped the spiders’ reactions.

The spiders detected and responded to tones emitted at a relatively far distance of three meters. In response to speakers placed at oblique angles to the web, the spiders rapidly turned toward the source of the sound. The authors also used ‘Doppler vibrometry’ to measure the webs’ motion induced by test tones. The webs followed the movement of air particles with high fidelity and efficiency, exceeding the acoustic responsiveness of eardrums.

The authors suggest the orb webs act as reconfigurable antennas, expanding the spiders’ sensory surface to 10,000 times their body size. According to the authors, the results enrich the scientific understanding of spider silk and could inform the design of acoustic flow detectors.

(With inputs from ANI)