Figure 1
F. De Lillo et al., Phys. Rev. Lett. (2014)

Swimming in Circles. Experimental data (left) and simulation (right) of gyrotactic plankton in a rotating tank, with consecutive time-steps (going from top to bottom) separated by roughly 60 seconds. The organisms swim toward the center, opposing the dominant centrifugal force, whereas dead plankton spread uniformly throughout the fluid (not shown). (See video below of turbulent simulation.)