a, Posterior lateral line organs at 2 d.p.f. (cldnb:lynGFP). Organ positions were identified from intensity profiles using peakFinder_R. b, Density profile of distance between consecutive organ positions (first, second, third and fourth spacing interval; see Fig. 1a). c, List of potential parameters affecting organ spacing. d, cldnb:lynGFP and brightfield overlay image. Spheres indicate colour code representing individual organs used in further analysis. e, Upper panel, kymograph (x–t graph) from a 17.6 h time-lapse movie, where the y axis represents time and the x axis represents distance. Lower panel, segmented kymograph of primordium migration (green) and myotome growth (dashed lines) through time. f, g, Calculated position (f) and velocity (g) of each organ through time. Asterisk shows the time point when organ disengages from the migrating collective. h, Second organ acceleration through time. Organ deposition is defined as the time where acceleration is minimum. i, Growth-effect-subtracted velocity of each organ through time (solid lines) versus observed velocities (dashed line). j, Reconstruction of organ positions from growth-subtracted velocities. k, Comparing spacing, average velocity and time between consecutive depositions for first, second, third and fourth interval (normalized to maximum). l, Correlation of time, distance and average velocities between consecutive depositions. Statistics: Spearman N = 82, n = 260, x–t r2 = 0.77, x–v r2 = 0.25, v–t r2 = −0.07. Scale bars, 500 μm (a), 200 µm, 5 h (d, e).