Movie 3

Free locomotion of groups of stage 1 and stage 3 larvae
(A) Showing a group of stage 1 larvae moving freely in the 55 mm × 55 mm test arena for 7 min (5-fold time-lapse) recorded with FIM and analysed with FIMTrack (Risse et al. 2013; Risse et al. 2014). Trajectories are blended in after 25 s. The larvae alternate between brief go and reorientation phases; most of the phase transitions lead to changes in bearing > 30° which we defined as turns (Fig. 7G). When compared to stage 3 larvae (Movie 5), the relatively smaller ‘exploration range’ in stage 1 larvae (Fig. 7H) manifests largely by differences in bending and turning behaviour (Fig. 7F, G), rather than in speed (Fig. 7E).
(B) Likewise showing a group of stage 3 larvae moving freely in the 225 mm × 225 mm test arena for 5.3 min (5-fold time-lapse) recorded with FIM and analysed with FIMTrack (Risse et al. 2013; Risse et al. 2014). Trajectories are blended in after 15 s. Similar to stage 1 larvae, also stage 3 larvae alternate between go- and reorientation phases, however relatively fewer of the phase transitions lead to changes in bearing > 30° which we defined as turns (Fig. 7G). Together with differences in bending behaviour (Fig. 7F), this results in a larger exploration range in stage 3 than in stage 1 larvae, even when normalized to body length (Fig. 7H).