Filmed 8 December 1990 at Lady Musgrave Lagoon at 21:10, in the Capricorn and Bunker Group at Great Barrier Reef, Queensland, Australia. Corals are marine organisms from the class Anthozoa and exist as small sea anemonelike polyps. The group includes the important reef builders that are found in tropical oceans, which secrete calcium carbonate to form a hard skeleton. They are formed from thousands of individual but genetically identical polyps, each polyp only a few millimeters in diameter. They grow by asexual reproduction of the individual polyps. Corals also breed sexually by spawning, with corals of the same species releasing gametes simultaneously over a period of one to several nights around a full moon. Although corals can catch small fish and animals such as plankton using stinging cells on their tentacles, these animals obtain most of their nutrients from photosynthetic unicellular algae called zooxanthellae. Consequently, most corals depend on sunlight and grow in clear and shallow water. These corals are develop in tropical and subtropical waters, such as the enormous Great Barrier Reef off the coast of Queensland, Australia.