what+is+coral?


 * =====Corals are marine organism's from the class //Anthozoa// and exist as small sea anemone-like polyps, typically in colonies of many individuals.=====
 * =====The group includes the important reef builders that are found in tropical oceans, which secrete calcium carbonate, to form a hard shell.=====
 * =====Corals can catch small fish like plankton using special stinging cells on their tentacles. These animals obtain most of their nutrients from photosynthetic unicellular algae called //zooxanthellae//. They obtain this sunlight by only forming under water from 10 to 60 meters deep.=====
 * Reef-building corals secrete on external skeletal cup of calcium carbonate. This skeletal cup protects the polyps. When the polyps contracts, it's completely inside the skeletal cup.


 * Little is known about the lifespan of corals, normally corals live up to several decades or centuries.[[image:butterfly_fish align="right" caption="butterflyfish"]]
 * Predator's of the coral: parrot fishes, butterfly fishes and sea stars.
 * Many of you have probably heard of "bleaching". This occurs when corals expel their //zooxanthellae.// As a result, the coloration of the coral fades. Although scientist aren't sure why this occurs, but they assure it's from the elevated water temperature.
 * Also many tropical storms can strip corals miles from their reef habitat's.
 * Corals do not have a brain, instead they have a simple nervous system called a "nerve net". The nerve net extends from the mouth of the tentacles.
 * There are 66 different types of corals. //Acropora, Agariciidae, Black corals, Cupcorals, Euphyllidae, Faviidae, Fungidae, Gorgonians, Motipora, Pocilloporidae, Poritidae, siderastreidae, Soft corals, Wire corals and zoanthids// are the most common corals.