Purcell’s scallop theorem states that swimmers deforming their shapes in a time-reversible manner (“reciprocal” motion) cannot swim. Using numerical simulations and theoretical calculations we show here that, in a fluctuating environment, reciprocal swimmers undergo, on time scales larger than that of their rotational diffusion, diffusive dynamics with enhanced diffusivities, possibly by orders of magnitude, above normal translational diffusion. Reciprocal actuation does therefore lead to a significant advantage over nonmotile behavior for small organisms such as marine bacteria.

• Received 8 February 2011
• Publisher error corrected 11 May 2011

DOI:https://doi.org/10.1103/PhysRevLett.106.178101