Corals of the Caribbean
 
For the novice snorkeler or diver in the Caribbean, the fascinating array of creatures, colors and shapes found on coral reefs can be a bit overwhelming at first. As one becomes accustomed to both equipment and surroundings, more attention can be paid to the reef's details. With a little practice and a good waterproof ID chart, identifying these corals will become fun and sometimes challenging. 

Corals have readily seen pores in which its polyps live and help identification by pore size, relief from the coral, or distance between them. One of the most commonly seen corals in this region isn't really a coral: it's a hydroid. The infamous "fire coral" (Millepora spp.) is orange-yellow in color and doesn't seem to have any pores. It does have visible stinging structures which can be painful to come into contact with. This organism forms encrusting colonies which can assume the shape of its support structure. 

Another predominant Caribbean coral is Montastrea annularis, or "mountainous star coral". This coral is considered to be an important reef former and builds 
massive colonies. Its cups are slightly raised above the coral surface and its shape can be columnar, encrusting, knobby, or keeled. There is no uniform color for this species. Its relative, "cavernous star coral" (Montastrea cavernosa) is more readily distinguished by its very large and raised cups. 

If you see a coral that looks fuzzy and the whole structure looks like giant fingers, it is probably "pillar coral" (Dendrogyra cylindrus). The tentacles of this coral are extended during the day, unlike most other species, and its "fingers" can grow to several feet in height. 

There are many species of "brain coral" (Diploria spp.) whose distinctions can baffle experts; therefore, this genera will generalized. Colonies can reach three feet in diameter and are usually rounded heads: the really huge (6 ft. diam.) brain corals are Colpophyllia natans.
 
Colpophyllia natans 
Colpophyllia natans
The common name refers to the fold and grooves on the corals' surfaces. The differences between the grooves are the keys to proper identification: I suggest picking up a good coral ID book to satisfy any further curiosity. 
Two related and easily discerned species are the two local varieties of Acropora. Elkhorn coral (A. palmata) has wide, flattened branches and its raised polyps give it a nubby texture. Staghorn coral (A. cervicornis) has thinner, tapering branches and looks almost fragile. This species also has the nubby texture. Both varieties are a bright burnt-orange color and can be very dense in certain areas. 
 
If you encounter a coral that looks like lettuce leaves with ridges, then it is in the genus Agaricia. These are also called "leaf corals", due to the foliose morphology. 

Another coral which can be very abundant locally is "finger coral" (Porites porites). It has large pores, grows in thick colonies, and has branches which are swollen at the tips. It is distinctly gray and its tentacles are often exposed in the daytime. Its cousin, P. asteroides, forms yellow or green lumpy masses which generally grow to about 1 ft in diameter. Both can be found in shallow water. 

There are many more corals to be found throughout the Caribbean. However, this report is very introductory and several excellent field guides are available which can greatly enhance one's species identification.
 
Text source: http://www.uvi.edu/coral.reefer/coralid.htm
Photo source: Karibik, by Humann, Stoll, & Ritter, 1989, Sturtz Verlag Wurzburg
 
 
coral ~ fishes ~ swimming critters ~ floor critters