Fig. 5. Visualisation of the spatial extent of the fish's wakes. For this figure, each vector field was reduced to a row by averaging over the columns of the vector field, and the rows resulting from this procedure were assembled in temporal order. Note that the velocity scale does not cover the complete range of measured values (cf. Figs 3, 4 and Table 1) in order to resolve the low velocities in the aged trail. A shows two Lepomis wakes, B shows two Colomesus wakes and C shows two Thysochromis wakes (see Table 1 for survey of trials).