Fig. 5. Plot of lateral excursion of the apices of the median fins relative to the body for approximately one tail beat at 1.0 L s^-1. Values are means ± S.E.M. from four tail-beat cycles for all fish and are unfiltered. Note that sometimes the standard error is small enough to be contained by the data symbol. Black circles represent a point at 80% L, gray circles represent the apex of the dorsal fin, white circles represent the apex of the anal fin, and triangles and squares represent the tips of the dorsal and ventral lobes of the caudal fin, respectively (inset). The lateral excursions of dorsal and anal fin tips are slightly less than 180° out-of-phase with the body, but are similar to each other in magnitude and phase. The phasing of the caudal fin is shifted ahead of the body, resulting from approximately one wavelength being contained between the point at 80% L and the caudal fin. The amplitudes of the anterior median fins are similar to the amplitude of the point 80% down the body.