REPRODUCTION AND DEVELOPMENT OF THE BLUE CORAL HELIOPORA-COERULEA (ALCYONARIA, COENOTHECALIA)

Up to the present time, the reproductive cycle and larval development of Heliopora coerulea, living fossil and sole member of the alcyonarian order Coenothecalia, have been undescribed. Populations of H. coerulea studied on the Great Barrier Reef between 1984 and 1989 were found to have separate sexes and an annual gametogenic cycle. Mature eggs were large (>800 μm diam), and their development was initiated internally. There appeared to be a lunar or semi-lunar periodicity in reproductive behaviour, with brooding of larvae commencing around either full or new moon. Development proceeded via superficial cleavage and a solid stereoblastula. Subsequent development took place on the surface of the colony, within a temporary brood-space created by protracted distension of the polyps. Larvae lacked zooxanthellae and were brooded for between 6 and 14 d prior to leaving the colony. Reproduction and development reflected the taxonomic affinities of H. coerulea, but brooding and embryological development also appeared to be constrained by its morphology. Reproductive and larval characteristics of H. coerulea may offer a partial explanation of the current biogeographic range of H. coerulea. © 1990 Springer-Verlag.