Figure 6.

Capillarity waves produced by the different types of leg kinematics of G. substriatus swimming on the water surface. The diagrams on the right correspond to the photographs on the left and represent the beetle (in grey) and the shape of the waves produced and visible in the photos. The waves produced by the hind leg strokes are shown in red, the waves produced by the middle leg strokes in blue and the waves produced by the beetle body in black. The blue arrow shows a middle leg, the red arrow indicates a hind leg and the black arrow shows the whole beetle. Waves produced by type I leg kinematics correspond to the blue wave shape induced by the middle leg stroke in (a). The waves shown in (a) and (b) are small circular waves produced by type II leg kinematics. Panels (c) and (d) show characteristic waves for type III leg kinematics, with a succession of two trains of circular waves (c) and V-shape waves (d). The spiral wave produced by type II leg kinematics is shown in (e). Only the shadows of the waves are visible on the photograph. The light was not directly above the beetle, giving the impression that the insect is not in the centre of the spiral. The grey arrow indicates the real position of the beetle relative to the waves and its direction.