Upper panel: fraction of all stars in the tail, N_tl, normalised to the total number of stars, N_tot, as a function of time. The results for lower mass and more massive clusters are shown by dashed and solid lines, respectively. The age of the Pleiades is indicated by the vertical yellow line. Middle panel: fraction of the tail stars N_tl, I/N_tl which belong to tail I. Lower panel: time dependence of the velocity dispersion σ_cl for stars within the star cluster. The observed velocity dispersion for the Pleiades and its 1σ error according to Raboud & Mermilliod (1998) is indicated by the horizontal yellow band.