Fig. 1

The swarming colony – a multiscale view. a A macroscopic top-view of a swarm colony grown on an agar plate, indicating the region where microscopic analysis is performed (the size of the frame is a bit larger than the entire field shown in (b)). b A microscopic view of the colony; cells are nearly resolved in the multilayered structure. Frame indicates the region where optical flow measurements are performed. c The highest magnification of the colony (taken using a 60X objective lens), d TEM images of bacteria taken from the swarm. Multiple flagella are visible. e The velocity and vorticity fields of the region in (c). Black arrows indicate instantaneous (and local) velocity, and colors indicate vorticity (scale bar in rad/sec)