Fig. 2. Normal horizontal swimming of an intact lamprey with its dorsal side up. Nine consecutive frames are shown. (A) Side view, (B) top view of the lamprey. The frames in A and B are stacked, with no forward movement indicated. (C) Body flexions in the sagittal plane. (D) Body flexions in the frontal plane. (E) The curvature data presented in the transverse plane. Data points corresponding to the same frame are connected with lines. The points and lines for all 9 frames are superimposed.