Scaling of Jumping Performance in Click Beetles (Coleoptera: Elateridae).

Abstract

Click beetles (Coleoptera: Elateridae) are known for their unique clicking mechanism that generates a powerful legless jump. From an inverted position, click beetles jump by rapidly accelerating their center of mass (COM) upwards. Prior studies on the click beetle jump have focused on relatively small species (body length ranging from 7 to 24 mm) and have assumed that the COM follows a ballistics trajectory during the airborne phase. In this study, we record the jump and the morphology of 38 specimens from diverse click beetle genera (body length varying from 7 to 37 mm) to investigate how body length and jumping performance scale across the mass range. The experimental results are used to test the ballistics motion assumption. We derive the first morphometric scaling laws for click beetles and provide evidence that the click beetle body scales isometrically with increasing body mass. Linear and nonlinear statistical models are developed to study the jumping kinematics. Modeling results show that mass is not a predictor of jump height, take-off angle, velocity at take-off, and maximum acceleration. The ballistics motion assumption is strongly supported. This work provides a modeling framework to reconstruct complete morphological data sets and predict the jumping performance of click beetles from various shapes and sizes.