Contained in neritic zone, in warm tropical
waters, Coral Reefs constitue a conspicuous and distinctive biome.
The currents and waves constantly renew their nutrient supply and the photic
zone that extent to the ocean floor allows photsynthesis. The reefs
are dominated by the structure of the corals that occupy it. Corals are a diverse group
of Cnidarians that secrete a calcitic hard external skeleton. The
varying shape of the reef systems form a substrate on which the newer corals
and algae grow. The coral animals themselves are preditorial
but require to be within the photic zone due their symbiotic relantionship
with dionoflagellates. They also rely on the photic zone to supply
them with micro-organism and organic matter, which themselves are photosynthetic
organisms. the reef systems are the most diverse and productive biome
on the planet. This is dictated by the immense variety of micro-organisms,
invertebrates and fish who m live among the reefs. Found in the biome
are herbivores which are predominately snails, sea urchins, and fishes.
The herbivores are in turn cosummed by predetory octopus and carnivorous
fishes. Reef communities are very old and are threatenned continuously
by human encroachment.