The specialized locomotory apparatus of the freshwater hatchetfish family Gasteropelecidae



High-speed video (200 frames/second) and kinematic analysis of the specialized locomotion of the Gasteropelecidae reveal a take-off mechanism from water to air with highly stereotyped components: a bilateral pectoral fin abduction and a C-start. With variations in timing between components of the take-off mechanism, a wide range of trajectories, all consistent with projectile motion, can be elicited. Correlated with studies of pectoral and caudal osteology and myology, the analysis indicates that active flight in the gasteropelecids is unlikely. Rather, the mechanism produces a jump, a modified startle response, achieved through the activation of powerful abductor muscles through the Mauthner mediated cell complex.