Relation between the specific star formation rate and the stellar mass (left) and stellar mass surface density (right) for HI-normal (HI-def ≤ 0.4; filled dots) and HI-deficient (HI-def >  0.4; empty circles) galaxies. The large filled blue dots indicate the mean values for normal gas-rich systems, and the empty red dots show mean values for HI-deficient galaxies. The error bar shows the standard deviation of the distribution for the large symbols. The dashed line shows the limit between star-forming and quiescent galaxies. The typical uncertainty in the data is shown in the lower left corner of each panel.