soft coral

subclass of cnidarians

Also known as: Alcyonaria, octocoral

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July 13, 2026

Quick Summary

Soft corals are marine invertebrates belonging to the class Anthozoa within the phylum Cnidaria. They are characterized by internal skeletons composed of calcareous spicules. These spicules, which vary in shape, stiffen the colony and can be needle-like, club-shaped, or anchor-shaped. Soft corals are colonial, with individual polyps forming a fleshy mass. They are common in shallow tropical seas and contribute to reef construction by cementing skeletal debris between hard coral skeletons. Unlike stony corals, soft corals have eight feathery tentacles and eight partitions (septa) within their gastrovascular cavity.12345

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cnidarian
Size range and diversity of structure
…of most hydroids, hydrocorals, and soft and hard corals, however, proliferate asexually into colonies, which can attain much greater size and longevity than their component polyps. Certain tropical sea anemones (class Anthozoa) may be a metre in diameter, and some temperate ones are nearly that tall. Anthozoans are long-lived, both…
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…of most hydroids, hydrocorals, and soft and hard corals, however, proliferate asexually into colonies, which can attain much greater size and longevity than their component polyps. Certain tropical sea anemones (class Anthozoa) may be a metre in diameter, and some temperate ones are nearly that tall. Anthozoans are long-lived, both…
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cnidarian
Annotated classification
Subclass Alcyonaria Octocorals. Polyps with 8 pinnately branched tentacles, 8 mesenteries, and a single siphonoglyph. Nearly all colonial with internal skeletons. Order Stolonifera Polyps of colony connected by stolons. Skeletons of spicules or horny external cuticle. Shallow tropical and temperate seas. Order
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Subclass Alcyonaria Octocorals. Polyps with 8 pinnately branched tentacles, 8 mesenteries, and a single siphonoglyph. Nearly all colonial with internal skeletons. Order Stolonifera Polyps of colony connected by stolons. Skeletons of spicules or horny external cuticle. Shallow tropical and temperate seas. Order
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skeleton
Crystals
In some corals (Alcyonaria), spicules combine with fibres made of keratin (a protein also found in hair and feathers) or keratins with amorphous calcite (noncrystalline calcium carbonate) to form axial structures of great strength and size, enabling colonies to reach large bushlike proportions.
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In some corals (Alcyonaria), spicules combine with fibres made of keratin (a protein also found in hair and feathers) or keratins with amorphous calcite (noncrystalline calcium carbonate) to form axial structures of great strength and size, enabling colonies to reach large bushlike proportions.
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