Fig. 12. Vortex production at the start of swimming in the final-stage larva. (A) The initially extended body contracts rapidly to one side, producing a vortex that propagates along an axis lying at right angles to the extended body and intersecting it approximately half-way along its length. The straight open-headed arrows indicate the direction of motion of the vortex and the centre of gravity (filled circle) of the body. (B) The outer diameters (2Re) of vortices measured at various times during the propagation of the vortex in 33 separate experiments.
