Sponge zoanthid (Umimayanthus parasiticus)

Classification (WoRMS)

Full classification as recorded by WoRMS: Kingdom: Animalia · Phylum: Cnidaria · Class: Hexacorallia · Order: Zoantharia · Family: Parazoanthidae · Genus: Umimayanthus.

Accepted name: Umimayanthus parasiticus · Authority: (Duchassaing de Fonbressin & Michelotti, 1860) · Taxonomic status: accepted · AphiaID: 847839.

Synonyms and superseded combinations recorded for this taxon: Parazoanthus parasiticus (Duchassaing de Fonbressin & Michelotti, 1860); Parazoanthus separatus Duerden, 1900; Zoanthus parasiticus Duchassaing de Fonbressin & Michelotti, 1860.

Source: World Register of Marine Species (WoRMS) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=847839 (CC BY 4.0). Accessed 2026-09-23.

Biology and life history (SeaLifeBase)

Measured values published by SeaLifeBase for Umimayanthus parasiticus. Only fields the database actually holds for this species are shown; these are database values, not aquarium guidance.

Habitat zone: sessile · Aquarium trade: never/rarely.

SeaLifeBase notes: This is a commensal species found in coral reefs particularly in subtidal areas (Ref. 83915).

Source: SeaLifeBase species summary (SpecCode 139413) — https://www.sealifebase.se/summary/Umimayanthus-parasiticus.html (CC BY-NC 3.0 — non-commercial use only). Accessed 2026-09-23.

Distribution and occurrence records (GBIF)

576 georeferenced occurrence records for Umimayanthus parasiticus are published through GBIF from 27 countries or marine areas. The map above plots 56 distinct locations from a sample of 576 records, omitting 8 inland records that carry an institution's coordinates rather than a collection site; it shows where the species has been observed and reported, not a modelled range.

Most records by country or area: Guadeloupe (253); Martinique (75); Cayman Islands (38); Bonaire, Sint Eustatius and Saba (34); United States of America (31); Mexico (29); Dominica (28); Bermuda (21); Bahamas (10); Panama (8); Curaçao (7); Honduras (7); Puerto Rico (6); Cuba (5); Jamaica (4).

Source: GBIF Occurrence Search (taxonKey 7978938) — https://www.gbif.org/occurrence/search?taxon_key=7978938&has_coordinate=true (records CC0 / CC BY); WoRMS distribution records (MarineRegions) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=847839 (CC BY 4.0); Natural Earth 110m basemap — https://www.naturalearthdata.com/ (public domain). Accessed 2026-09-23.

Description and natural history (Wikipedia)

The polyps of Umimayanthus parasiticus superficially resemble rather small sea anemones. They grow either singly or in small groups of two or three on the surface of certain species of sponge. The polyps are joined by a thin layer of tissue called coenenchyme and occur at densities of 3 to 10 per square centimetre (20 to 60 per square inch). The distances between the polyps widens as they spread out over the surface of the host sponge by budding. The polyp's column is encrusted with sand particles and calcareous material and is white. The oral disc is up to 6 mm in diameter and there are two rings of tentacles round the edge with about 14 tentacles in each. These are brown and contain symbiotic zooxanthellae, unicellular photosynthetic algae which supply the polyp with nutrients while benefiting from its nitrogenous waste.

Umimayanthus parasiticus is found in the Caribbean Sea, the Gulf of Mexico, Florida, Bermuda and the Bahamas at depths varying from 7.5 to 30 m. It is common where its host sponges are found. These include Cliona deletrix and other Cliona spp., Gelloides ramosa, Callyspongia vaginalis and Spheciospongia spp..

Like other corals, the polyps of Umimayanthus parasiticus extend their tentacles to feed on zooplankton. It is probable that the coral benefits from the flow of water into and out of the sponge which increases the number of food particles coming within its reach. The sponge is a filter feeder and feeds on the bacteria and dissolved organic matter it removes from the water passing through its tissues. The presence of the coral obstructs the inflow of water. Some sponges produce anti-fouling compounds which they release into the surrounding water to try to prevent other organisms colonizing their surface. Nevertheless, an ongoing study of sponges colonized by zoanthid corals showed positive benefits to the sponge in growth and survival rates so the association seems to be mutualistic.

The sexes are separate in Umimayanthus parasiticus. Oocytes start developing in February and become mature when the water temperature rises to about 27 °C in July. Spawning takes place precisely two nights after the full moon during the next three months, with the main spawning event taking place in September. The eggs are shed singly and contain no zooxanthellae and fertilisation occurs in the water column. Little is known of the development of the larvae.

Source: Wikipedia: Umimayanthus parasiticus — https://en.wikipedia.org/wiki/Umimayanthus_parasiticus (CC BY-SA 4.0). Accessed 2026-09-23.