Surfing Turbulence: a strategy for plankton navigation*

We explain how microswimmers, such as planktonic organisms, can use a local measure of velocity

gradients of the flow to navigate efficiently in complex 3D flows. Following the observation that

despite its chaotic properties turbulence present exploitable correlation times, we derive an analytic

strategy, solution of a local optimum, that we test in simulated 3D homogeneous isotropic turbulence.

Given a fixed target direction, this strategy allows microswimmers to surf the surrounding flow and

increase their velocity along this direction, up to 100% in best cases. Best results are obtained for

low swimming velocities (of the order of the Kolmogorov velocity) that are in agreement with

various biological plankton species swimming velocities.