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

Fleming, C. B. "The Coral Polyp." Science 80 1, 7 (November 1980): 105-106.

Reef environments may include natural enemies of the corals. These enemies either remove the living coral tissue or they burrow into the coral and weaken it. Starfish such as Acanthaster planci can consume an entire small colony of coral; parts of larger colonies are usually left uneaten. Other natural enemies include echinoids, annelid worms, copepods, cirripedes, crabs, gastropod mollusks, and fish. There are also cases of one coral species attacking another coral species.

Reef coral taxonomy has not reached a definitive stage yet. However, it can be said that the western Atlantic region contains "a relatively homogeneous faunal assemblage of hermatypic scleractinian species." Areas that this holds true for include the Caribbean Sea, the Greater and Lesser Antilles, the Gulf of Mexico, the Bahamas, Bermuda, and southern Florida. Large barrier reefs are present in the Caribbean, off the coast of British Honduras, and there are fringing reefs off the narrow insular shelf along Jamaica's north coast. River runoff and the detrimental effects of the high seas may explain the absence of coral reefs off the north coast of Puerto Rico.

Corals grow fastest with maximum light--calcification rates were found to be doubled on sunny days when compared to cloudy days. Heavy shade can be lethal to corals. Deep water species appear adapted to low light. Corals may compete for space in the light; indirect interference of Acropora by shading out Montipora has been shown.

Melzak, M. "Chemical Warfare on the Coral Reef." New Scientist 89, 1245 (19 March 1981): 733-735.

The actual coral polyp is a double-walled cylinder. At the top of the polyp is a mouth with tentacles. The tentacles trap plankton, the food source of the corals. The coral polyp produces limy secretions a