Introduction
Biological communities in shallow limestone formations create coral reef in tropical and subtropical waters (Kleypas et al, 2001). Coral reef used to be a hazard to marine navigators but now they are valued for their beauty, biodiversity, and the usefulness and utility they provide to human society. These organisms are distinct from most other animals in two important ways.
Firstly, most of them consist of multiple small, sea anemone-like organisms called Polyps connected by living tissue into one sheet-like colony.
Secondly, they have evolved a close symbiotic relationship within a group of micro algae: small plants, called zooxanthellae, living in large numbers within the tissue of the coral animals.
This fusion of plant and animal creates a composite organism: numerous coral polyps and a much larger number of algal cells all connected into a single living entity. In most cases, the colony can be subdivided into pieces that will continue to live; just like plant cuttings can be disseminated.
Reefs perhaps found in high-nutrient waters, but the coral colony’s ability to feed as an animal and photosynthesize as a plant gives it great survival advantages even in the tropical “deserts” of the ocean, poor-nutrient waters. However, this dependence on light restricts corals, and especially extensive reef-building activity, to shallow depths (from the inter tidal zone to no more than 100 meters) and relatively clear waters. Most reefs, therefore, crop up near land, making them particularly vulnerable to exploitation by humans on nearby landmasses.
Advantage of coral reef to society
Although coral reefs cover less than one percent of the ocean floor, they are home to more than 93,000 plant and animal species, and sustain more than 35 percent of marine species in shallow ocean waters. In fact, it is estimated that more than one million coral reef species remain to be identified...................
