Fig. 8. Promotor muscle intensity during sound-producing and non-sound-producing movements. Mean values are indicated by horizontal bars. Lateral promotor lobe intensity (A), medial promotor lobe intensity (B) and the relative intensity of the two lobes (medial lobe intensity minus lateral lobe intensity) (C) are shown across individual lobsters (1-5) and three movement categories, no movement (F), posterior movement with no sound production (P) and sound production (R). See Materials and methods for the calculation of muscle intensity.