Fig. 1. Prorocentrum minimum motility described in Miyasaka et al. (1998). (A) P. minimum cell and directional terminology used in the present study. (B) Swimming trajectory. (C) Sutural view, (D) valval view, (E) anterior view, as indicated in A. Open arrows indicate wave directions. AE, anterior end; a₁, amplitude of the longitudinal flagellum; ap, antero-posterior axis; a_t, amplitude of the transverse flagellum; LF, longitudinal flagellum; PE, posterior end; p_n, the half-pitch corresponding to the adjacent parts to the ap axis of the transverse flagellum; p_f, remote part; P_p, pitch of helical swimming trajectory; R_p, radius of helical swimming trajectory; S, suture of two valves; TF, transverse flagellum; the pitch angle of the cell against the axis of the swimming trajectory; _p, the pitch angle of the cell against the axis of the swimming trajectory; ₁, angle between the cellular antero-posterior axis and the center line of oscillation of longitudinal flagellum; ₁, wavelength of the longitudinal flagellum; _t, wavelength of the transverse flagellum.