Fig. 6.

Relationship between lateral acceleration (solid line) and tail beat amplitude (dashed line) of Kármán gaiting trout. (A) Lateral acceleration and tail beat amplitude profiles of one representative fish during one tail beat cycle. Tail beat amplitude lagged behind lateral acceleration by ~90 deg. When the anterior body was in the middle of the vortex street (t=0 s, t=0.24 s and t=48 s, thick lines), the tail beat amplitude was at its most lateral excursion. At these time points, the lateral acceleration was zero (horizontal dashed line). In contrast, lateral acceleration was at a maximum when the anterior body changed direction of motion (t=0.12 s and t=0.36 s, thin lines). In these instances, the tail beat amplitude was at the middle of the vortex street and continued moving along the same direction. (B) Phase-space plot between tail beat amplitude and lateral acceleration confirms the correlation between these two variables.