Yeah, the Navier‑Stokes equations do cover that kind of twisting motion. They’re the equations that link the viscous forces and the inertia of a fluid, and when you look at the vorticity term you see how a small swirl can be sustained or amplified. For a tiny plankton, the Reynolds number is very low, so the flow is dominated by viscosity, and the equations predict a smooth, helical stream‑tube around it. So in principle, the twist you see is exactly the sort of vortex that the Navier‑Stokes framework explains, though the exact shape would depend on the organism’s surface geometry and how it moves in the water.