Distribution of the currently observed CALIFA galaxies in the u − z vs. M_z color–magnitude diagram. Different colors and symbols represent a classification into spheroid- and disk-dominated galaxies as well as intermediate cases, as suggested by the concentration index C (see Sect. 2 for definition). For comparison, the contours delineate the number density distribution of galaxies in the SDSS-NYU catalogue (e.g., Blanton et al. 2005). The small dots indicate the remaining objects in the CALIFA mother sample, not observed so far.