Reefs, Non-coral

Although most modern reefs are communities of coral and coralline algae that live in clear, well-lit tropical and subtropical waters, there are many different groups of reef-forming organisms that are found on living and ancient reefs. The modern non-coral reefs thrive in a wide range of environments extending from sponge reefs in the arctic to non-photosymbiotic algae and Halimeda reefs found near methane seeping faults at depths of 600 m (Wood 1999).

Definitions of Reefs

The word, reef, is derived from the Norwegian word, rif, which means rib. In nautical terms, reef refers to a narrow chain of rocks, shingle or sand lying at or near to the surface of the water. When early sailing ships explored the tropical waters of the South Pacific, they encountered ring-like reefs of coral that enclosed a lagoon which they called “atoll” after “atolu,” the Malayalam name for the Maldives Islands. In the more restrictive modern use of the word, reef denotes a rigid, wave-resistant...