Corals reefs are one of the world's most diverse and unique underwater organisms. Not only do they grow in the shallow waters near the shores of the tropics but they also thrive in the deep cold waters of the ocean.
Shallow coral reefs reside in well lit, shallow, opaque tropical waters. Not only do they display a myriad of extremely bright and beautiful colors but they also support a dynamic and incredibly diverse ecosystem filled with thousands of unique marine animal species. The survival of the shallow water coral species is dependant upon the symbiotic relationship they have with algae that reside within their soft tissue filaments. Coral polyps offer a safe protected living environment for the algae with access to plenty of light for photosynthesis. Algae provide their host with the necessary nutritional components and natural gases required for the sustenance of life.
Shallow water reef building corals thrive in an environment of warm shallow water containing a hard substrate to which they can attach. These coral structures can only survive in water temperatures between 23-25 degrees Celsius. As a result these specific coral are restricted shallow areas of tropical water occurring between 30N and 30S latitude. Cold water impairs the ability of the coral to effectively and efficiently secrete calcium carbonate. Significant water depths prevent the penetration and amount of light required by the symbiotic algae for photosynthesis. Deep waters are also susceptible to more turbulent water conditions which can easily destroy the coral reef colonies.
Deep water corals reside in the cold deep waters of the ocean. They are so far down that they are no longer exposed to sunlight or UV rays. These coral colonies are similar to shallow water colonies in that they both require a hard substrate to initially attach to in order to continue to grow and develop. Colonies of deep water corals vary in shape and size and can appear as a mound, cone or branching tree. These corals come in several textures but there are two basic types which include soft and fleshy or hard and stony.
Many of the excessively large coral structures of the deep ocean waters have been found to be in existence and undisturbed for up to four hundred years. In fact, Norway scientists have discovered stony coral reefs that have lived for approximately two thousand years. As a result, these particular coral are some of the oldest living beings on the planet.
Some deep-water corals do not form reefs in the same manner as their shallow water counterparts. Instead they appear as small patches or communities. Regardless of their formation they are still referred to as reefs. Deep-water corals create a supportive environment for various fish including sea bass, snapper, porgy and shrimp.