The Zoantharia are solitary or colonial Anthozoa; many secrete an exoskeleton of calcium carbonate, which is why this subclass has a long fossil record. The skeletal elements consist of:
Zoantharia are also termed Hexacorallia; they usually exhibit either sixfold symmetry or a multiple thereof. The group can be divided into two based on whether the mesenteries occur singly, as in the black corals and tube anemones, or in pairs, as in all others.
- radial skeletal elements (septa, costae and pali);
- tangential skeletal elements (eutheca, pseudotheca and epitheca);
- horizontal skeletal elements (tabulae, dissepiments and synapticulae);
- central skeletal elements (columella and aulos).
The subclass Zoantharia includes the coral orders Rugosa, Tabulata and Scleractinia as well as sea anemones and zoanthid soft corals.
Corals predominantly inhabit shallow seas but are reported to depths of up to 6000m. Most are hermatypic, i.e. they build reefs, and prefer shallow, warm seas. Optimum conditions are in the photic zone, with water temperatures of 25-28 degrees celsius and salinities between 35 and 40 ppt.
Click the thumbnails below to find out more about the three main coral groups within Zoantharia:
Author: Ben Kotrc
Last updated: 21 November 2005
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