Are swimming fish dual oscillator systems? A case study using free-swimming smooth dogfish sharks (Mustelus canis).

Fish swimming has classically been modeled as a rearwardly propagating wave of increasing amplitude and fixed frequency, based on kinematic data from large numbers of species in captivity. However, recent work on sharks swimming in natural environments has suggested that anterior and posterior body segments oscillate at different frequencies from each other. We attached accelerometer, gyroscope, and magnetometer data loggers to the anterior and posterior body sections of smooth dogfish, Mustelus canis (n=4), and released these individuals in the wild.