Octocorals are belong to the phylum cnidarians and to the class Anthozoa.
They are marina organisms, with the polyp stage. They are simlar to stony corals in that they have a skeleton but a rather internal one, kind of like vertebrates. But it is a non-living skeleton.
They have tentacles like feathers because they have side branches to one side only.
All their polyps are cemented and connected via their thick mass of mesoglea called a coenchyme.
the mesoglea contains amebocytes and these cells are what secrete the internal skeleton.
The skeleton could be of 2 types, either made of gorgonin or simply cemented calcium carbonate spicules.
This characterisitc splits the octocorals into 2 groups: gorgonians and soft corals.
Gorgonian organisms such as the sea fans, feathers and precious red corals. With the exception of precious red corals which has a calcium carbonate axial skeleton, the gorgonians are placed perpendicular to the water current to maximize food encounter. they form extensively branched colonies supported by an internal skeleton made of protein collagen hard mixtures called gorgonin. The color of the internal axial calcium carbonate skeleton of precious red corals is depended on the species called Corallium rubrum. That skeleton is exported for jewellery usually.
on both sides of the axial skeleton, mesoglea is found anchoring feeding polyps with their tentacles
Soft corals like the sea pansies and sea pens lack an axial cemented internal skeleton. Instead, it is made of calcium carbonate spicules dispersed in the mesoglea. These organisms are found at soft sandy bottoms and have a primrary polyp and a secondary feeding polyp. those secondary polyps share food with the primary polyps. Soft corals accumulate and produce fatty acid substances that function in giving a bad taste to soft corals to deter fish from eating them, and making them disagreeable for crabs and animals to settle on them. so it serves as a defense mechanism.
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