Hydractiniidae Family of Hydrocoral

Staghorn Hydrocoral, Janaria mirabilis. A representative of the Hydractiniidae Family of Hydrocorals.

Phylogeny:  The Hydrocorals are members of the Hydractiniidae Family, that are also known as the Calcified Hydroids, and like sea anemones, hard corals, and jellyfish, are in the Phylum Cnidaria. They are in the Class Hydrozoa and the Order Anthoathecata and the Suborder Filifera.

Distribution:  Hydractiniidae Hydrocorals are found globally, in all temperate and tropical and temperate seas. They reside attached to algae, gastropod shells and rocks from the intertidal zone to depths up of 200 m (655 feet). There are currently one hundred and fifteen species in the Hydractiniidae Family of which only this species being found along the Pacific Coast of Mexico.

Morphology:  The Hydractiniidae Hydrocorals are Athecate indicative that in their polyp stage they are unprotected by a holster in their polyp stage in contrast to Thecate Polyps. They are hydrocorals are colonial organisms that consist of four types of multi-cellular, interdependent, animals (zooids). Like hard corals, they build a calcareous skeleton however grow slowly and do not significantly contribute to reef building. They may exist as an encrusting, interconnecting mat or a branching hydrocoral. Like other corals, the mouth is surrounded by tentacles that have nematocysts (or cnidocysts) that are capable of delivering a toxic sting in order to capture prey or repel predators.

Ecosystem Roles:  Hydractiniidae Hydrocorals primarily consume amphipods and other plankton from the surrounding water. Since their polyps are immovable these corals reside in locations that have moving water caused by wave action and currents. In turn they are preyed upon by crabs, fish, gastropods, starfish and polychaete worms.