a) Featureless: Bacillus subtilis 3610. Featureless swarms are made when cells spread evenly and continuously outward from the point of inoculation as a monolayer. Cell density in the monolayer is high and roughly uniform throughout the swarm, increasingly slightly at the advancing edge.
b) Bull's eye: Proteus mirabilis PM7002
c) Dendritic: Pseudomonas aeruginosa PA14
d) Vortex: Paenibacillus vortex V
e) and f) A non-swarming mutant and subsequent suppressor in Bacillus subtilis 3610. Uncolonized agar appears black and bacterial biomass is white.
Source: NCBI
Bacteria Swarming Patterns