Fig. 9. Schematic diagram of the force balance on Triakis semifasciata swimming at 1.0 Ls^-1, where L is total body length, while holding position (also representative of Chiloscyllium punctatum), rising and sinking in the water column. The yellow circle represents the center of mass, and vectors indicate forces F exerted by the fish on the fluid. Lift forces are generated by the ventral body surface, both anterior and posterior to the center of mass. The jet produced by the beating of the tail maintains a constant angle relative to body angle and path angle and results in an anterodorsally directed reaction force oriented dorsal to the center of mass during all three behaviors, supporting the classical model. Data on pectoral fin function are from Wilga and Lauder (2000, 2001). Tail vortex jet angles are predicted mean values from Table 2.