Fig. 5. Directional change of heartbeat, analyzed by the metachrony along five sensor sites in D. melanogaster (female 2). (A) Transition from anterograde to retrograde beating. Arrowheads indicate double peaks during diastole. (B) Transition from retrograde to anterograde beating. The first anterograde pulse collides with a retrograde pulse at the anterior sensor point (asterisk). Explanations as in Fig. 4.