Probability density distributions of stellar orbits and the distributions of stellar ages within R_e vs. circularity λ_z for each of the 82 CALIFA spirals. Each column in the top panel shows the orbit probability P(λ_z) of a certain circularity bin (y-axis) for a galaxy (x-axis), as indicated by the colour bar. The sequence of galaxies along the x-axis is sorted by increasing stellar mass from left to right, with the positions of some typical stellar mass log(M_*/ M_⊙) shown at the top of the figure. For each galaxy, the average circularity of all stellar orbits is calculated, with the black folded line denoting its variation with stellar mass. The results in the top panel originally come from Fig. 2 of Zhu et al. (2018b), which plots a similar orbit distribution for each of 300 CALIFA galaxies. The bottom panel correspondingly presents the age t of each circularity bin for each galaxy, with bluer pixels indicating younger stellar populations and redder pixels denoting older populations. The horizontal dashed lines in the top and middle panels divide the cold (λ_z ≥ 0.8), warm (0.25 < λ_z < 0.8), and hot (λ_z < 0.25, including the counter-rotating orbits) components.