Plankton active response to turbulence suggests surfing strategy

Despite predominantly being thought to drift with the ocean currents, plankton may be able to enhance their transport in their swimming direction by taking advantage of certain flow features. For example, Monthiller et al., Phys. Rev. Lett. 129, 064502 (2022) recently theorized a “surfing’’ strategy, where plankton preferentially sample upwelling areas of the flow by simply sensing and reorienting in response to the local velocity gradients. Here, we present experimental evidence that suggests real plankton may in fact be able to surf turbulence. We study a planktonic larval snail as our model organism. By observing these plankton in a jet-stirred turbulence tank, we find that they have complex responses to velocity gradients, and that they tend to actively oppose the flow’s rotation. This is the opposite of what would be expected from passively rotating bottom-heavy plankton. This active orientational response is similar to the behavior of simulated surfing plankton, and suggests that real plankton may be able to surf turbulence.