Fig. 8. An analysis of the average trajectory of the foot of the great cormorant relative to still water and the resulting hydrodynamic forces (the same data as in Figs 6, 7). Black squares mark the position of the center of hydrodynamic forces of the foot in the XY plane. The positions of this point were used to calculate the trajectory, speed and angle of attack (AoA) of the foot. Red lines connect between points 4 and 5 in Fig. 1 and represent the webbed surface of the foot in the XY plane, demonstrating the AoA between this surface and the foot trajectory. The motion relative to still water, calculated for the center of hydrodynamic forces, fitted a circle (black line) with a radius of 6.6 cm. The speed (red) and the AoA (black) are aligned with each relevant point in the table to the left. Motion starts from the bottom and follows the arch of the circle up. The values of AoA and speed are organized in bottom-to-top order as well. Lift forces (green arrows) will be directed at a perpendicular angle to the foot trajectory and, in this case, toward the center of the circle. Drag (blue) is directed at the opposite direction to the motion of the feet, and in this case the inertial force (black) is in the same direction as drag. Forces smaller than 0.5 N were omitted from the figure.