Coral reefs are one of the wonders of the natural world.  They cover only a very small percentages of one percent of the floor of world’s oceans, but they provide a habitat for approximately a quarter of world’s fish.  They are found for the most part in the more tropical areas of the world where there tends to be relatively few nutrients in the water; yet they create an incredibly rich ecosystem of marine life.
Most of these reefs are found in rather shallow and clear water. 

The shallowness of the water exposes reefs to more turbulence than if they were deep below the surface, but that is actually a stimulant for reefs to develop more complex structures. There are many configurations of coral reefs.  For example some are connected directly to the shore and extent out into the ocean.  Other create a long barrier to the shore some distance out from the shore and over time tend to protect the shore from large waives.  Still others develop in circles resulting in a lagoon in the middle, often due to an original small island sinking.  Some coral reefs develop over time to create their own small islands which are called “cays”, which in some instances can fertile environments which can support a human population of thousands.  


Coral are small marine animals with exoskeletons that layer upon one another. Over time, sometimes over millions of years they can grow to be enormous and stretch for hundreds, even up to a thousand miles or more.  The great barrier reef off the coast of Australia is the world’s largest example of this. Even thought the structural foundation of coral reefs is solid, made of calcium carbonate and can maintain and grow over eons, they can actually deteriorate rapidly if optimal conditions are not maintained for them.  In the past 100 years and especially the past 50 years or so, coral reefs around the world have been deteriorating dramatically. The causes are varied from. Water pollution is an important example.  Even too many tourist watching fish in and around reefs who wear tanning oils and are careless in terms of stepping on reefs can have a serious deleterious effect.  There has been extensive commercial harvesting of coral which has devastated whole reefs.
In the mean time if mankind can restrain itself from continuing to destroy these great natural wonders, these reefs play a key role in sustaining marine life. One will find a huge variety of marine life in these reefs.  Every aspect of these reefs ends up a niche for a particular kind of life in complex ecosystem.  Small fish live in and around the protective coral structures on the surface of reefs.  Invertebrates such as an octopus can squeeze into tiny spaces and eels find narrow spaces to lodge their bodies.  One will find the most colorful fish in the world living there.  Large predator fish, even some species of shark, live and swim around the periphery of the reefs.  All of this more visible life is supported by a vast array of very small animal and plant life which grow and circulate in and around coral reefs.  
The fact that these reefs grow and flourish in what could otherwise be called ocean deserts with very little life is the ultimate statement of their uniqueness.  Their destruction would have devastating effect on not only the marine but the entire global ecosystem.