Colour–colour plot with AKARI bands, using N2,N3,S7 and S11. Dots (black) and small crosses (green) indicate galaxies and stars, respectively, detected at more than 3σ in all of 4 bands. Solid line (red) indicates the colour of Sc galaxy template as a function of redshift. Dot-dashed (black) and dashed (blue) lines are for Sb galaxy and M 82 template, respectively. The SED templates are taken from Polletta et al. (2007).