Figure 4.

The impact of a point sink mouth assumption. A suction feeding event without prey interaction is simulated using the suction boundary condition of figure 2. Four lines emanating from the centre of the mouth at different angles are examined (a). The fluid speed along the ray is plotted against the distance from the mouth (normalized to gape) (b). Far from the mouth (>1 gape distance), all of the plots converge to the same value. Close to the mouth (<0.5 gape distance) the fluid speed along these rays decreases as the angles increase. Since the prey is located close to the mouth during a suction feeding event, these changes result in significant changes in the forces exerted on the prey (solid line, 0°; dotted line, 15°; dashed dotted line, 30°; dashed line, 45°).