GAMETOGENESIS AND EARLY DEVELOPMENT OF THE TEMPERATE CORALASTRANGIA DANAE(ANTHOZOA: SCLERACTINIA)

Abstract

1. The coral Astrangia danae is dioecious, with an early age of first reproduction. 2. In Narragansett Bay, this species exhibits an annual reproductive cycle with gametogenesis starting in March-April. Spawning occurs during August, and vestigial gametes are absorbed during the winter months. 3. Gametes originate from interstitial cells which differentiate in the mesenterial mesoglea. 4. Ova are 100-130-µm in diameter and sperm are 2-3-µm in length, excluding the tails. Egg production was estimated at up to 6000 eggs per polyp. 5. Fertilization and development are external; no fertilization membrane was seen even though a layer of cortical vesicles was present before fertilization. 6. Embryonic cell divisions are around 30 min apart and the larval planual stage is reached within 12-15 hr after fertilization. Larval settlement was not observed. 7. Ova from colonies containing zooxanthellae did not contain zooxanthellae when spawned.