Fig. 9. Principal component analysis of muscle activity duration, relative onset of muscle activity and electromyographic (EMG) burst intensity of all intrinsic caudal muscles except the red axial myomeres during kick-and-glide (red triangles), braking (white diamonds) and backing maneuvers (green squares), and normal swimming at 1.2 L s^–1 (black circles) (Flammang and Lauder, 2008). Each point represents one sequence in which all caudal muscle activity is measured for a given swimming behavior. Further explanation of principal component loadings (Table 1) are given in the text.