Developmental Variability (Pelagic and Benthic) in Haminoea callidegenita (Opisthobranchia: Cephalaspidea) is Influenced by Egg Mass Jelly

¹ Bamfield Marine Station, Bamfield, British Columbia, Canada V0R 1B0

Haminoea callidegenita Gibson and Chia (1989) has a pattern of development similar to that of other lecithotrophic opisthobranchs, except for the stage at hatching. In this species, both veligers and juveniles hatch from each egg mass. The percent of each hatching stage was variable among masses, with most masses having 30 to 50% of total hatchlings emerging as veligers. Both veligers and juveniles emerge throughout the entire hatching period (lasting 3-11 days), although the percentage of veligers decreases during this period. Encapsulated embryos cultured without egg mass jelly had approximately 80% of the total hatchlings emerging as veligers. Separated embryos cultured in the presence of egg mass jelly pieces hatched with percentages of veligers similar to that observed in intact egg masses, suggesting the possibility of a diffusible compound present in the jelly mass that induces intracapsular metamorphosis. Egg mass jelly also induces metamorphosis in hatched veligers. A juvenile and adult food source (the green alga Chaetomorpha linum) induces extracapsular metamorphosis only.