Cnidaria:Anthozoa:Octocorallia

Introduction: Octocorals, also known as alcyonarians, belong to the class Octocorallia, within the subphylum Anthozoa of the phylum Cnidaria.These organisms are exclusively marine, benthic, and sessile, and are characterized by colonies composed of polyps exhibiting eight-fold radial symmetry.Although they resemble stony corals in general morphology and polyp size, octocorals are distinguished by the absence of a rigid calcium carbonate exoskeleton and by their distinctive polyp symmetry.In most octocorals, structural support is provided by microscopic skeletal elements called sclerites, composed of calcium carbonate and embedded within the mesoglea, which contribute to the rigidity and growth of the colony.Each polyp possesses eight pinnate tentacles and eight mesenteries, consistent with the defining features of Octocorallia.Like all cnidarians, octocorals exhibit a complex life cycle that includes a motile, planktonic larval stage, followed by a sessile adult stage, during which they become permanently attached to the substrate.Global diversity: The order encompasses 3608 described species in three orders viz., Malacalcyonacea, Scleralcyonacea, and Octocorallia inserte sedis. Diversity in India:In India, 397 species belonging to 93 genera and 38 families in three orders are recorded.