Fertilized eggs develop into the free-swimming plankton called planula larvae. With further development, the larvae settle, attach to the bottom and change into young adults with 6 tentacles and a basal disc for attaching to the substrate. Growth, then, comes about as the coral colony expands in size by the budding of new polyps. Budding may occur at the base or at the oral disc of old polyps. Feeding Although there are many exceptions , most corals feed at night and contract during the day.
Corals feed like sea anemones.
The prey size ranges from small fish down to small zooplankton, depending on the size of the polyps. Corals continuously feed at night in correspondence to the vertical migration of plankton. Digestion is rapid. Corals store their food in the form of fat and glycogen. Fish dart in to feed on the exposed polyps when the polyps are feeding on the plankton.