Young paralarvae have been identified from Hawaiian waters. At 5.6 mm ML the paralarva has small clubs, with a single chromatophore on the club's aboral surface; the dorsal head and eyes hae 3 chromatophores as does the ventral head and eyes (one chromatophore is hidden by the funnel). The mantle has five small chromatophores dorsally and two ventrally and a pair of large chromatophores near the posterior tip of the mantle.
Figure. Dorsal and ventral views of paralarval S. melancholicus, 5.6 mm ML, Hawaiian waters. Note the small tentacular clubs and the sparse pigmentation. Drawing by R. young.
The arms of the mature male are modified. They are broad proximally and have expanded protective membranes. Distally membranes are absent and suckers greatly reduced in size and in more than two series on arms II and III.
Figure. Dorsal view of a mature male S. melancholicus. Drawing from Voss, 1980, p. 387.
Large subadults become rather heavily pigmented (photographs below) The tentacles are absent and only a slight scar indicats where the tentacles once were.