Jumping mechanism in the marsh beetles (Coleoptera: Scirtidae)

Abstract

AbstractThe jumping mechanism with supporting morphology and kinematics is described in the marsh beetle Scirtes hemisphaericus (Coleoptera: Scirtidae). In marsh beetles, the jump is performed by the hind legs by the rapid extension of the hind tibia. The kinematic parameters of the jump are: 139–1536 m s−2 (acceleration), 0.4–1.9 m s−1 (velocity), 2.7–8.4 ms (time to take-off), 0.2–5.4 × 10–6 J (kinetic energy) and 14–156 (g-force). The power output of a jumping leg during the jumping movement is 3.5 × 103 to 9.6 × 103 W kg−1. A resilin-bearing elastic extensor ligament is considered to be the structure that accumulates the elastic strain energy. The functional model of the jumping involving an active latching mechanism is proposed. The latching mechanism is represented by the conical projection of the tibial flexor sclerite inserted into the corresponding socket of the tibial base. Unlocking is triggered by the contraction of flexor muscle pulling the tibial flexor sclerite backwards which in turn comes out of the socket. According to the kinematic parameters, the time of full extension of the hind tibia, and the value of the jumping leg power output, this jumping mechanism is supposed to be latch-mediated spring actuation using the contribution of elastically stored strain energy.