Fig. 3. Kinematic variables during continuous swimming in the pupa. (A) Changes in the forward velocity of the centre of gravity relative to the water during a complete downstroke/upstroke cycle. The cartoons represent the configuration of the body at the corresponding points in the cycle. Open and filled arrowheads represent the motion of the abdomen and head/thorax, respectively, around the centre of gravity. (B) Changes in the forward velocity component of the centre of gravity (filled circles, also shown in A) and the abdominal paddles (open circles). The hatched parts of the graph represent the parts of the swimming cycle when the abdominal paddles are moving backwards with respect to the mean swimming path through the water. (C) Changes in the angular velocity of the abdominal paddles about the centre of gravity, relative to the longitudinal axis of the head/thorax: this motion is indicated by the open-headed arrow in the cartoon on the right. (D) Changes in the angular velocity of the longitudinal axis of the head/thorax about the centre of gravity, relative to the water. This motion is indicated by the filled arrow in the cartoon on the right. The vertical dotted lines in B–D indicate the point, in the middle of a half-stroke, when the forward velocity of the centre of gravity is at its peak. The dashed lines demarcate the half-strokes and pause periods.