Coral Field Guide
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What is the distribution of Coral Communities in Hong Kong? Do you know the Basic Biology of Hard Corals? Coral feeding and symbiosis with Zooxanthellae
Hard corals feed on zooplankton. Many of them feed at night so the tentacles are only extended nocturnally, and are retracted into their corallites during daytime. A significant proportion of hard corals have symbiotic unicellular algae called zooxanthellae in their tissues.
These algae utilize the organic wastes generated by the corals for their growth, and in turn provide additional organic materials to the corals from the products of their photosynthetic activities. The presence of this symbiotic interaction between corals and algae significantly increases the rate by which the corals deposit their calcareous skeleton. Hence, only those hard corals that have symbiotic algae can build reef. These hard corals with symbiotic algae are therefore often referred to as the reef building corals (or hermatypic corals) and those without symbiotic algae are called the non-reef building corals (or ahermatypic corals). In most cases, when people talk about hard corals in the coral reef, they are actually referring to those reef building corals. |
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