Fig. 1. Recording and analysing muscle contractions in freely moving Drosophila larvae. (A) Four images from a movie of a first-instar larva during forward crawling (a wave of muscle contractions that propagate from posterior to anterior, propelling the larva forward). Images are enlarged and selected to show onset of contraction (i,ii) and beginning of relaxation (iii,iv) in muscles of segment A5, during the sequence. (B) Entire sequence (two waves of forward peristalsis showing all abdominal segments) analysed frame-by-frame, with onsets and offsets of ventral longitudinal muscle contractions on either side of the animal in segments A1-7 documented.