while the algae produce energy. The polyps become active at night to gather food.Corals usually reproduce during the night and at certain times of the year. Corals generally spawn in response to lunar cycles. The most well known example of spawning in response to lunar cycles are the mass spawning events in the Pacific and Caribbean stony corals. During this stage, the corals produce a milky cloud of eggs and sperm. If this took place during the day, the eggs and sperm would be quickly eaten by fish and other predators. After the eggs are fertilized and they hatch into larvae, they drift with the current for several days to several weeks before settling on a hard surface. As soon as they land they begin to construct skeletons to attach themselves to the rock. At this time the larvae change from shapeless masses to polyps with tentacles and mouths. The polyp will remain in one place its entire life, growing new polyps by cloning itself. This process is called budding. (Corals, Architects of the Reef, 1997)During their lives, coral polyps extract calcium from the seawater and mix it with carbon dioxide to build protective limestone skeletons. These skeletons form the gradually evolving framework of the huge and colorful coral reefs. The living polyps grow on a graveyard filled with James W. Hyde BIOL 1040countless skeletons of other polyps. Coral reefs are built polyp by polyp, this process is usually very slow: estimates of growth range from one to six...
