Epizoanthids of the Epizonathidae Family

Red Epizoanthid, Epizoanthus Sp. A representative of the Epizonathidae Family of Epizonanthids.

Phylogeny:  Epizoanthids of the Epizoanthidae Family, like hydroids, jellyfish and sea anemones are in the Phylum Cnidaria. There are seven species in the one Genus of the Family.  They are in the Class Anthozoa  and the Order Zoantharia.

Distribution:  Epizoanthids are found worldwide, in temperate and tropical seas. There are more than eighty species in this Epizoanthidae Family with at least four species found along Mexico’s Pacific Coast. Zoa, or Zoanthids, may utilize embedded sand or other material including calcareous tubes, to support their body column. Those that live in colonies are connected, at their bases, by a sheet of tissue known as a coenchyme. Epizoanthids are epizootic, indicative that they often reside on the outer surface of other animals, such as sponges, hydroids, gorgonian skeletons, and gastropod shells, especially when the shell is occupied by a hermit crab. Those that do not live in an epizootic manner are found on hard substrates such as rock. They are found from the intertidal zone to depths greater than 3,000 m (9,840 feet).

Morphology: Epizoanthids have radial symmetry, a hollow digestive cavity, and specialized stinging structures in tentacles surrounding the mouth. Their polyps have a flower-like appearance, with the tentacles located on the margin of the disk.  They have two rows of tentacles, and usually, a colonial lifestyle.

Ecosystem Roles:  Unlike many other Zoanthids, Epizoanthids are not zooxanthellate and  they obtain all their necessary nutrients by using their tentacles to capture plankton from the surrounding water. In turn they are preyed on by gastropods, fish and nudibranchs. Zoanthids contain palytoxin, a substance that is toxic to humans but only at an insignificant level although there are anecdotal stories of human affected by handling live specimens.

Reproduction:  Epizoanthids reproduce sexually, some species being male or female, while others are hermaphrodites.