Hard
Corals
Order Madreporaria
These are organisms
whose compact calcareous exoskeletons build coral reefs. Many species
occur on the reef edge, but the beachcomber is unlikely to encounter
many of them except when the tides are very low.
Hard corals are distinguished by their calcium carbonate (chalk) skeletons,
and symbiotic zooxanthellae (photosynthesising algae) living in their
tissues which confer the characteristic colours of coral polyps (the
actual animals). These algae are able to use sunlight and the carbon
dioxide produced by their hosts (the coral) to produce sugars which
are shared. They are hence vital to the coral's ability to produce
its skeleton and helps explain why they are only common in clear,
sunlit waters. |
Tubinaria
Goniastrea
Acropora
Platygyra |
Fungia
Pocillopora
Oulastrea
 Herpolitha |
