Epizonathidae Family of Epizoanthids

Two Epizoanthids of the Epizonathidae Family can be found in this website:

Phylogeny: Epizoanthids of the Epizoanthidae Family, like hydroids, jellyfish and sea anemones are in the phylum Cnidaria. They are in the subphylum Anthozoa, the class Hexacorallia, the  order Zoantharia, and the suborder Macrocnemina. The Epizoanthidae Family contains two genera and eighty-six species. The name epizoanthidae comes from the Greek words meaning “upon anemones”, referring to there habit of growing on other organisms.

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 around twenty tentacles, in two rows, located on the margin of the disk. 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 may be white, yellow, tan, green, red, or brown in color. The individual polyps of colonial species are fairly small only reaching around 4 mm (0.1 inches) in diameter. Solitary species reach a larger size with the larger species reaching 2 cm (0.75 inches) in diameter and 5 cm (2 inches) in height.

Distribution: Epizoanthids are epizootic, meaning 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). At least four species from this family are found in Mexican waters.

Reproduction:  Epizoanthids may be gonochoric (male or female for life) or hermaphroditic (having both male and female reproductive organs). They reproduce sexually, through broadcast spawning, with external fertilization. The fertilized eggs hatch into planktonic larvae. Epizoanthids may also reproduce asexually through fission or budding.

Ecosystem Roles: Unlike many other Zoanthids, Epizoanthids are not zooxanthellate and  they obtain all their necessary nutrients by using their tentacles to capture amphipods, fish larvae, invertebrate larvae, other zooplankton, and organic matter 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.