Reef Coral reefs house between 600,000 and 9 million species
25% of marine species rely on coral reefs at some point in their life cycle
32 of the 34 phyla of metazoans live on the reef
65% of marine fishes live in reefs

The most important groups of reef organisms include:
Other cnidarians (gorgonians, soft corals and hydrocorals)
Coralline algae
Calcareous green algae (Halimeda)
Sponges
Molluscs (Tridacna) * Echinoderms (sea urchins, sea cucumbers, starfishers and crinoids) * Crustaceans * Marine worms * Fishes * Bacteria * * Coralline algae are red algae which deposit calcium carbonate within cell walls. They are encrusting and help cement the reef together. They are particularly important on reef crests. * * Sponges help clean and filter surrounding water. They need constant water flow through their bodies and the skeleton can be made of calcium carbonate. They can have endosymbionts. * * Molluscs-Bivalves-Giant clams have a two-part shell and most are filter feeders. Epifauna and infauna. The mantle of a giant clam contains zooxanthellae. * * Molluscs-Gastropods-Nudibranch are shell-less marine gastropods with extremities on back used to breath. Most are carnivorous. * * Echinoderms-Starfish have five-fold radial symmetry and no external skeleton. The endoskeleton is a water vascular system. Starfish have hydraulic vascular system which aids in locomotion (two stomachs, predators). * *