Reproductive biology of the antarctic opisthobranch Philine gibba Strebel

Monthly samples (August 1974 to February 1976) and cultured material have been used to describe ovotestis maturation, spawning, and larval development of the Antarctic opisthobranch Philine gibba Strebel. Ovotestis maturation took one year and mature individuals (mean shell length 12 ± 1.4 mm) spawned a single egg mass in April–May containing 975–4760 eggs, 379 μm in diameter. Development was non-pelagic but an active veliger was observed within the egg capsule. Juveniles (mean shell length 375 ± 55 μm), which hatched from August to October, resembled adults except for the presence of eye spots and an exposed shell. The mantle enclosed the shell by February when shell length was 890 ± 30 μm.