2.  “Reef Builders”  Organisms that secrete the calcium carbonate skeletons that form the reef ▪ Examples:  Calcareous Corals  Coralline Algae

3.  Organisms that produce sediment or live in the cracks & crevices of the reef  Examples:  Encrusting coralline algae  Fragments of coral  Foraminifera  one-celled animals that make shells – for ex: paper shells  Mollusks  Echinoderms

4.  Organisms that use the structure of the reef to live and hide in; don’t affect the structure, but may eat inhabitants of be eaten by them  Examples: ▪ Anemones ▪ Crustaceans ▪ Many Fish ▪ Worms ▪ Red, green, brown algae ▪ Octopuses ▪ Many mollusks

5.  Organisms that destroy by chewing, eroding, blanketing, or producing acid  Examples: ▪ Boring sponges ▪ Coral-eating fish (ex: parrotfish) ▪ Worms ▪ Sea Urchins & Sea Stars ▪ Boring Mollusks ▪ Rapid-growing algae

6.  “Builders”  Examples: ▪ Calm Water ▪ Adequate sunlight ▪ Optimum salinity ▪ Clear water ▪ Solid substrate ▪ Adequate nutrients

7.  Actions & Organisms that kill coral and wear away the reef  Examples: ▪ Pounding waves ▪ Moving sand ▪ Smothering sediments (silt) ▪ Freshwater rain ▪ Very low tides ▪ Rising seafloor ▪ Sinking seafloor ▪ Rising or falling water temperature ▪ Runoff from land ▪ Excessive nutrients in water ▪ Pollution