Fig. 2. Intermittent kinematics typical of the routine swimming of zebrafish. (A) Video frames at 0.10 s intervals illustrate the changes in body shape that occur during beat and coast phases of this adult (L=30.2 mm). Orange lines denote the cranial position in the first video frame, which travels along the body as the fish moves forward. The cranial orientation () and angular fin position () are illustrated in the first frame. (B) Fin position () reflects the posture of the body during beat (white bars) and coast (gray bar) phases. (C) Body rotation is shown by changes in cranial orientation () during the beat phase. (D) Measurements of the cranial position during coasting were used for non-linear curve fitting of Eqn 4 (red line) in order to calculate the initial speed, time constant and coasting distance.