Fish Locomotion

Fish use body undulations to swim, which create water movement with great acceleration behind the fish. The form of this wave is similar among most fish, however waves vary in number, speed, and amplitude change. There is little known about how the center of mass (COM) of fish changes with swimming speed. However, it is known that the COM can change in three dimensions: surge, sway, and heave. The COM of three fish were calculated. Surge COM displacement and acceleration in eels and bluegill sunfish oscillated at twice the tail beat frequency, while the sway COM displacement and acceleration oscillated at the tail beat frequency. Surge COM oscillations did not change with swimming speed, while sway oscillations increased with increasing swimming speed. Sway amplitudes increased with increased swimming speed in bluegill sunfish, but the same was not true for the eels.