Fig. 4. Posterior view of fish (images above plot), mean lateral excursion of tail fin (A), mean tail fin height (B), and activity of intrinsic caudal muscles (C) throughout one tail beat during steady swimming at 1.2 L s^–1 (N=14). Lateral excursion and tail height are plotted as mean (circles) ± s.e.m. Colored horizontal bars denote muscle activity within 75% confidence interval (CI) and error bars denote the 95% CI. Muscle activity is shown for the left (L) and right (R) sides; supracarinalis (SC), hypochordal longitudinalis (HL), flexor dorsalis (FD), interradialis (IR) designated by the number of the dorsally corresponding fin ray, flexor ventralis (FV), infracarinalis (IC), lateralis superficialis (LS), and red myomere on the right side of the caudal peduncle. Dotted vertical lines indicate the times of each image at the top. Bar color corresponds to the anatomical diagram in Fig. 1.