Only eggs or only sperm have been seen for many other species. This suggests the presence of unisexual colonies or colonies that undergo sex change as they age. This indicates cross-fertilization for species such as Acropora durvillei, Turbinaria species, Sphneotrochus rubescens, Coenopsammia species, Acropora plamata, Isophyllia sinuosa, Montastrea cavernosa, Sideratrea radians, and Symphyllia recta, as well as Pavona cactus.
Fertilization may be internal or external. Reproduction may be seasonal or continue throughout the year. The release of planwas shown to have a marked lunar periodicity in Pocillopora bulbosa. Winter spawning of this species coincided with the full moon, while summer and autumn spawning coincided with the new moon. Agarica fragilis in the Bermudan Atlantic Ocean and Manicina areolata in the Tortugas Atlantic Ocean only released planulae in summer. The Hawaiian corals Pocillopora damicornis and Cyphastrea ocellina released planulae every month of the year.
Corals with large polyps tend to have many eggs per polyp. Favia doreyensis of Low Isles had a minimum of 93 eggs. Porites haddoni varied from 6 to 250 planulae per colony. Pocillopora bulbosa had from 1 to 100 planulae per colony based upon collection of a group of branches. Thus, a moderate size colony may produce a few thousand planulae (eggs) per breeding season.
Newly released planulae may swim upward and towards the light. Some planulae swim away from