| Coenothecalia | |
|---|---|
| Blue coral (Heliopora coerulea) | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Cnidaria |
| Class: | Anthozoa |
| Subclass: | Octocorallia |
| Order: | Coenothecalia Bourne, 1895[1] |
| Families | |
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| Synonyms | |
Coenothecalia (also known as Helioporacea) is an order of the class Alcyonaria that forms massive lobed crystalline calcareous skeletons in colonial corals. These corals first appeared in the Cretaceous period and includes the modern genus, Heliopora coerulea,[2] also known as Blue coral.
Heliopora coerulea, or Blue coral, (the only species in the family Helioporidae) is most common in shallow water of the tropical Pacific[3] or Indo-Pacific reefs.[4] Coenothecalia (Helioporidae) have no spicules, and is the only Octocoral known to produce a massive skeleton formed of fibrocrystalline aragonite fused into lamellae, similar to that of scleractinia. They form in large colonies more than 1 meter in diameter, that may be massive, or most commonly, composed of vertical branches or folia.
The surface appearances of Blue coral is very smooth, and the color in life is a distinctive grey-brown with white tips. The entire skeleton, however, has an unusual blue color and therefore the species is commonly exploited for decorative uses.[5] The blue color of the skeleton (which is covered with a layer of brown polyps) is caused by iron salts. Blue coral can be used in tropical aquariums, and the crystalline calcareous fibres in the skeletons can be used for jewelry.
Individual polyps have eight feathery tentacles and, in the gastrovascular cavity, eight septa, or partitions. Cilia (tiny hairlike projections) on six septa draw water into the cavity. Cilia on the other two septa expel water. The skeleton consists of spicules that form a protective cup around each polyp.[6]