Fig. 7. Flow fields close to the body of a swimming eel, shown in gray. The lateral position of the eel's snout (off the view) is shown as a black arrow. Velocities are phase averaged across 14 tail beats by interpolating the normal gridded coordinate system on to a system defined by the distance from the eel's body and the distance along the body from the head. Approximate positions of the proto-vortices, defined by Müller et al. (2001), are shown in red (clockwise rotation) and blue (counter-clockwise rotation).