The external calcareous reef skeleton is made by large groups of invertebrate coral. The reef is always built from calcium carbonate in the mineralogical form of calcite or aragonite crystals. The coral skeleton is built from aragonite needle crystals. A reef’s skeleton is produced by the ectoderm of the polyp in part called the calicoblastic ectoderm. This coral part is located on the walls and basal disc of a coral. Here, the polyp produces mucus where calcium carbonate can form and precipitate.

Coral polyps do not necessarily make up the majority of biomass, biological productivity, or calcification in the coral reef. The animal and plant community is formed because the corals extend to block waves. An example of the coral reef community is the 150-mile fringing reefs on the Northern coast of Jamaica.

The coral body is directly related to the reef’s overall skeleton.

Coral Reefs