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II. Types of corals
There are two main types of coral: non-reef builders (ahermatypic) and reef builders (hermatypic). Ahermatypic corals, such as soft corals and solitary hard corals, and they do not form reefs as they do not possess the symbiotic algae, Zooxanthellae in its internal body wall . Soft corals are colonial corals that have a flexible skeleton and depend on toxic chemicals in their tissues to protect themselves from predators. Hermatypic corals are reef forming corals and this is possible for them because they are known to harbour Zooxanthellae in their body wall. These are hard corals that form large colonies from thousands of connected polyps living together, sharing food and energy. Hard corals use zooxanthellae , to combine calcium and carbonate from the water and for respiration. The zooxanthellae are the coral’s solar panels and provide enough energy to build their skeletons rapidly. Generation after generation of polyps add to the skeleton, corals are known to attain variety of shapes and sizes. Coral colonies can grow bigger than a small house and can be several hundred years old. Over thousands of years, the skeletons of many coral colonies living together form reefs. |