Coral reefs are marine ridges or mounds, which have formed as a result of the deposition of calcium carbonate by living organisms, predominantly corals, but also a rich diversity of other organisms such as coralline algae and shellfish. Coral reefs provide a unique habitat characterised by high diversity and density of life. They occur globally in two distinct marine environments; deep, cold water (3-14°C) coral reefs, and shallow, warm water (21-30°C) coral reefs in tropical latitudes
Major coral reef sites are seen as red dots on this world map. Most of the reefs, with a few exceptions are found in tropical and semitropical waters, between 30° north and 30° south latitudes.
The condition of the growth of coral polyps.
1. High temperature- temperature above 20 degree Celsius.This is usually found in warm waters where the warm ocean current areas.
2. Clear shallow sea water- for the coral reef to survive well in seawater that is shallow and free from sediment. Coral need sunlight to grow , deep or muddy water is unsuitable.
3. Plentiful supply of oxygen and plankton- Coral need oxygen and plankton to grow. The part of the coast is washed by waves , currents and tides which maintain a fresh and plentiful supply of oxygen and plankton for the coral.