3D configuration of the clicking mechanism and controlling muscles in click beetles (Coleoptera: Elateridae)

Click beetles exhibit a unique locomotory behavior, which, when flipped on their back, allows them to self-right using a latching mechanism located between the pro- and meso-thorax. Without the reliance on leg-like structures, rather the storage and rapid release of elastic energy to self-right themselves, click beetles have become a source of inspiration for researchers seeking to design small jumping robots and other power-amplified mechanical systems. The study presented here used modern techniques to investigate the muscles associated with the latch mechanism to better understand the contribution of the springs, primarily muscles, that power the click beetle’s unique up-righting ability. In this study, click beetles of different species were fixed, stained, Micro-CT scanned, and 3D segmented to further understand the musculature relationships outlined in a study performed almost 50 years ago. Micro-CT combined with 3D segmentation proved to be an advantageous technique in isolating the thoracic muscles of click beetles. By implementing modern technology to explore the musculature, accurate information regarding special differences in muscle and cuticle geometry, body and muscle volume, and the arrangement of spring elements associated with the up-righting mechanism could be collected. Future studies may use this technique and protocol to further understand the mechanics of the clicking mechanism and aid in a simpler design of jumping robots or other power-amplified mechanisms.