Fig. 1. Kinematic events at the start of a pupal mini-dive. (A) Body profiles at 10ms intervals from the start of diving (0ms). The dorsal surface of the insect is indicated, in this and the following figures, by the projecting respiratory siphon. The filled and open circles in the resting position indicate the centre of gravity of the body and the abdominal paddles, respectively. The dashed lines indicate the position of the radius vector from the base to the tip of the abdomen in the resting and full-down (end-downstroke) positions. Arrows with open or filled heads indicate the direction of rotation of the abdomen and head/thorax about the centre of gravity, respectively. (B) The motion of the centre of gravity and abdominal paddles at the stages corresponding to those shown in A. (C) Abdominal tip and paddles.