Coral

Estimated area of coral reefs:

109,768.84 square miles of shallow coral reefs worldwide; 2,573.76 square miles and 5,317 square miles inside the 100-fathom (600 feet) depth curve around the Main Hawaiian Islands and the Northwestern Hawaiian Islands, respectively.

Biology

• Corals are tiny fixed animals called polyps that secrete a hard calcium carbonate skeleton serving to provide protection and a base for colony formation. These skeletal structures form reefs over time.


• Corals feed by extending their tentacles to catch small fish and planktonic species. Almost all corals that inhabit reefs have a symbiotic relationship with algae. The algae photosynthesizes inside the polyp to produce food for the coral in exchange for protection.


• The Northwestern and Main Hawaiian Island reefs support between 57 and 59 different coral species, many of which are endemic species. The waters of the Pacific/east Asia region of the world have the most diverse reefs with 500 - 600 species of coral.


• These highly important and productive ecosystems support about 25 percent of all marine life and around 2 million types of species.

Geography

• Coral reefs occupy less than 1 percent of the planet's surface, almost all of which are found in tropical and subtropical oceans (between 30ºS and 30ºN latitude) at depths less than 100 feet to allow significant light penetration and in seawater temperatures ranging from 64° - 84°F.


• Reefs can be classified into three categories: the most common, fringing reefs, which surround the shores of ocean islands; barrier reefs, which are platforms separated from the mainland by a bay or lagoon; and atolls which rest on the tops of submerged volcanoes.


• Reefs in the western Pacific are believed to be 50 - 59 million years old.