a Scanning electron microscopy of a typical C. crescentus rosette with numerous stalked cells and a flagellated predivisional cell (yellow). b Sample trajectories of 18 C. crescentus rosettes simultaneously recorded (in 10 min) via phase contrast microscopy. Those individual rosettes remaining in the view after 10 min are circled. A rosette is visible in the zoomed-in view (inset). c The mean-squared displacement (MSD) of nine rosettes (purple) demonstrates a crossover lag time (Δt ~ 1 s) demarcating the ballistic and diffusive regimes. The MSD of six individual solitary swarmer cells (green) shows a similar ballistic-diffusive transition, implying similarity in the temporal organization of power sources. Dashed lines, fits of the experimental data with both ballistic (MSD ∝ Δt2) and diffusive (MSD ∝ Δt) activities. Error bars correspond to standard deviations. The difference in sample size between b and c is due to the fact that not all trajectories in b are sufficiently long for MSD calculations (see “Methods”).
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