Elucidating the Relationships Between Spider Size, Joint Stiffness, and the Mechanical Frequency Response of the Body
Abstract
Spiders use vibrations to sense their surroundings. It has been suggested that the vibration perception in spiders may be altered by the mechanics of the body. I studied the biomechanics of spiders, at the level of leg joints and the whole body. To study joints, I quantified the allometry of leg joint stiffness in spiders. I found that the stiffness of spider joints increased nearly isometrically with increasing body mass, partly by having shorter and thicker leg segments and also by other unknown means. Using these data, I developed empirically validated biomechanical models which predicted the effects of mechanics on vibrational filtering within the body. Interestingly, both models and empirical data showed that the relatively linear increase in joint stiffness with mass meant that the mechanical filtering of spider bodies may be size independent, indicating that spiders of different masses or ecologies may sense the world in similar ways.