Violet Zoanthid, Zoanthus sansibarcus
Violet Zoanthid, Zoanthus sansibaricus. Underwater photograph taken in Zihuatanejo Bay, Guerrero, March 2018. Photograph courtesy of Ron Woheau, Zihuatanejo. Identification courtesy of Greg Timms, youtube.com/@Coralmasterdives-Puerto-Vallarta/videos.
Phylogeny: The Violet Zoanthid, Zoanthus sansibaricus (Carlgren, 1910), is a hexacorallian zoanthid in the Zoanthidae Family of Zoanthids. The Zoanthus Genus is one of three genera in the Zoanthidae Family, and there are twenty-two species in the Zoanthus Genus. The genus name Zoanthus is the combination of two Greek words meaning “animal-flower”. The species name sansibaricus comes from the German spelling of Zanzibar combined with the Latin ending that means “native to”. This refers to the location where this species was first collected and described. In Mexico they are known as Zoántido Violeto.
Morphology: The scientific community currently believes that there is no clear method of identifying species in the zoanthid genus Zoanthus has been established, due in part to the morphological plasticity of this genus (e.g., in polyp and colony form, oral disk color, tentacle number).” The Violet Zoanthid is a colonial species, with colonies reaching up to 1.5 square meters (16 square feet). The individual polyps range in size from 3 mm (0.1 inch) to 30 mm (1.3 inches) in height and 3 mm (0.1 inch) to 12 mm (0.5 inch) in diameter. The polyps can expand to 2.5 cm (1.9 inches ) in diameter. The polyps are erect and open in the daytime. The tentacles are located on the margin of the oral disk, giving the polyp a flower-like appearance and they have have from 40 to 60 tentacles. The oral disk is about twice as wide as the base. The oral disk and tentacles vary widely in color between colonies, including blue, brown, green, orange, purple, white, and yellow and at times these colors are fluorescent. The polyp stalks are light to dark purple. The polyps are connected by a coenenchyme, which is usually the same color as the polyp stalks, and unlike the coenenchyme in some species, is not covered with sand.
Habitat and Distribution: The Violet Zoanthid grows on rock and coral reef substrates. It is found from the intertidal zone to depths up to 52 m (170 feet), though most specimens are found in depths above 30 m (99 feet). Violet Zoanthids are found in the tropical waters of the Indian and Pacific Oceans and thier distribution in Mexican waters is very limitged and poorly documented. They are ENDEMIC to Mexican having beeen confirmed only from Manzanillo, Colima, to Zihuatanejo, Guererro.
Diet: The Violet Zoanthid is zooxanthellate, meaning that it has a symbiotic relationship with single-cell dinoflagellates, known as zooxanthellae. Zooxanthellae live within certain coral polyps, sea anemones, jellyfish, and nudibranchs. The zooxanthellae produce energy, during daylight, by means of photosynthesis. This energy is passed along to their hosts, sometimes providing up to 90% of the host’s total energy needs. In return, the host provides nutrients, carbon dioxide, and a secure, sunlit, platform for the zooxanthellae. The balance of their energy comes from collection of passing micro plankton and detritus with their tentacles which possess nematocysts.
Predators: Predation of the Violet Zoanthid is very poorly documented. They lack the chemical compounds used for defense found in some zoanthids. Other species in the genus are preyed upon by corallivorous fishes, nudibranchs, and sea stars.
Reproduction: Sources differ on the reproduction of Violet Zoanthids. Some say that both the polyp and the colony are usually simultaneous hermaphrodites (having both male and female reproductive organs) but some are gonochoric (male or female for life). Other sources say that the individual polyps are always either male, female, or asexual, and the colony is always hermaphroditic. Sexual reproduction takes place through broadcast spawning with external fertilization. The zygote develops into a planktonic planula larva, which later settles to the substrate and undergoes metamorphosis. Violet Zoanthids can also reproduce asexually, producing clones through budding or fusion.
Ecosystem Interaction: Other than the relationship with zoxanthellae discussed above, the Violet Zoanthid does not have any documented commensal, parasitic of symbiotic relationships.
Human Interaction: Violet Zoanthids are collected for the aquarium trade and also for their pharmacologic properties. Derivatives from cultured Violet Zoanthids have been shown to possess anti-cancer, anti-inflammatory, anti-oxidant and photoprotective properties. From a conservation perspective the Violet Zoanthid has not been formally evaluated.
Synonyms: Zoanthus cavernarum, Zoanthus cyanoides, Zoanthus erythrochloros, Zoanthus gnophodes, and Zoanthus zansibaricus.