A typical colonial pattern generated by P. vortex when grown on 2.25% (w/v) agar with 2% (w/v) peptone in a 9 cm Petri dish. A. Whole colony view. Each vortex (the condensed group of bacteria – the bright dots) is composed of many cells that swarm collectively around their common center at about 10 μm/s. B. An individual vortex – the diameter of the vortex is 75 μm. Both clockwise and anticlockwise rotating vortices are observed, although the majority have the same handedness.