The extraordinary biological diversity of reefs makes them biologically important. Like rainforests, reefs have provided valuable scientific insights into the nature of symbiosis, ecological competition, evolution, and animal behavior. The numerous species residing and depending on coral reefs represent a bank containing the genetic diversity necessary for adaptation to changes in the environment, both anthropogenic and natural. While most corals and large reef organisms have been described, the taxonomy of some is uncertain and many other organisms have yet to be described. A few principles governing patterns of diversity have emerged, however.
Large reefs tend to be more diverse than small, isolated reefs.
The most diverse reefs occur in seas north of Australia, such as the Java Sea, the waters of Indonesia, Papua New Guinea, the Phillipines, and the South China Sea. Although many coral reef species appear to be widely distributed, some have restricted ranges. These species would be especially vulnerable to local extirpation or extinction. For example, a newly discovered species of fire coral apparently restricted to the Gulf of Chiriqui, Panama, probably became extinct as a result of prolonged high temperatures during the 1982-1983 E1 Nino event. Two other fire coral species in the area suffered extreme reductions in range.