Zoantharia

{{Short description|Order of hexacorallians with marginal tentacles}} {{about|a subgroup of Hexacorallia|Zoantharia as a synonym of Hexacorallia|Hexacorallia}} {{More citations needed|date=October 2025}} {{Automatic taxobox | name = Zoanthids | image = Parazoanth2.JPG | image_caption = ''Parazoanthus axinellae'' | taxon = Zoantharia | diversity_link = | diversity = See text. }}

'''Zoanthids''' (also known as: '''zoanthiniarians''', '''zoantharians''' (proper), '''colonial anemones''', '''button polyps'''; scientific names: '''Zoanthiniaria''',<ref>Scrutton, Colin. (1997). The Palaeozoic corals, I: Origins and relationships. Proceedings of The Yorkshire Geological Society - PROC YORKS GEOL SOC. 51. 177-208</ref> '''Zoanthinaria''',<ref>{{cite book | last=Soliman | first=Gamil N. | title=Invertebrate Zoology: The noncoelomates | publisher=Palm Press | date=1996 | url=https://books.google.com/books?id=uFoWAQAAIAAJ&q=Zoanthinaria | access-date=2025-07-31 | page=155}}</ref> '''Zoantharia''',<ref>Sinniger F., Montoya-Burgos J.I., Chevaldonne P., Pawlowski J. (2005) Phylogeny of the order Zoantharia (Anthozoa, Hexacorallia) based on the mitochondrial ribosomal genes. Mar. Biol. 147 (5): 1121-1128.</ref> '''Zoanthidea''',<ref>{{cite book | last1=Hayward | first1=P. J. | last2=Ryland | first2=J. S. | title=Handbook of the Marine Fauna of North-West Europe | publisher=OUP Oxford | date=1995-06-29 | isbn=978-0-19-854055-7 | url=https://books.google.com/books?id=sZ8mdRT4jbIC&dq=Zoanthidea&pg=PA117 | access-date=2025-07-31 | page=117}}</ref> '''Zoanthidia''',<ref>{{cite web | title=Corals of the World | website=Corals of the World | date=2021-10-01 | url=https://www.coralsoftheworld.org/page/classification/ | access-date=2025-07-31}}</ref> '''Zoantharida'''<ref>MATIS, Dušan. Zoológia bezchordátov. Bratislava: Univerzita Komenského, 1997, p. 119. ISBN 8022311626</ref>) are an order of hexacorals.

Zoanthids are commonly found in coral reefs, the deep sea and many other marine environments around the world. These animals come in a variety of different colonizing formations and in numerous different colors. They can be found as individual polyps, attached by a fleshy stolon or a mat that can be created from small pieces of sediment, sand and rock. The term "zoanthid" refers to all animals within this order Zoantharia, and should not be confused with "''Zoanthus''", which is one genus within Zoantharia.

These are among the most commonly collected cnidarians in reef aquaria, easily propagating and very durable in many water conditions.

== Other use of the name Zoantharia == The name Zoantharia (but not the above mentioned variants of this name) is often used as a synonym of Hexacorallia, i. e. in a much broader sense than in this article.

==Characteristics== Zoanthids can be distinguished from other colonial anthozoans and soft coral by their characteristic of incorporating sand and other small pieces of material into their tissue to help make their structure (except for the family Zoanthidae). A main characteristic of the order is that their tentacles are all marginal. Most species propagate asexually and the offspring of the original polyp remain connected to each other, by a stolonal network or coenosarc. Some species are solitary.<ref>{{cite book|author=Light. Sol Felty |title=The Light and Smith Manual: Intertidal Invertebrates from Central California to Oregon|url=https://books.google.com/books?id=64jgZ1CfmB8C&pg=PA177 |year=2007 |publisher=University of California Press |isbn=978-0-520-23939-5 |page=177}}</ref>

While the most well-known zoanthids are the zooxanthellate containing genera found in tropical and sub-tropical waters (primarily ''Zoanthus'' and ''Palythoa''), many other species and genera exist, some still relatively unknown to science.<ref>Reimer J.D., Ono S., Iwama A., Tsukahara J., Takishita K., Maruyama T. (2006) Morphological and molecular revision of Zoanthus (Anthozoa: Hexacorallia) from southwestern Japan with description of two new species. Zoological Science 23 (3): 261-275.</ref><ref>Reimer J.D., Hirano S., Fujiwara Y., Sinniger F., Maruyama T. (2007) Morphological and molecular characterization of Abyssoanthus nankaiensis, a new family, new genus and new species of deep-sea zoanthid (Anthozoa: Hexacorallia: Zoantharia) from a northwest Pacific methane cold seep. Inv. Syst. 21: 255-262.</ref><ref>Reimer JD, Nonaka M, Sinniger F., Iwase F. (2008) Morphological and molecular characterization of a new genus and new species of parazoanthid (Anthozoa: Hexacorallia: Zoantharia) associated with Japanese red coral (Paracorallium japonicum) in southern Japan. Coral Reefs 27 (4):935–949.</ref><ref>Sinniger F., Häussermann V. (2009) Zoanthids (Cnidaria: Hexacorallia: Zoantharia) from shallow waters of the southern Chilean fjord region with the description of a new genus and two new species. Org. Div. Evol. 9:23–36</ref> Many zoanthids (in particular the genera Epizoanthus and Parazoanthus) are often found growing on other marine invertebrates.{{Citation needed|date=January 2025}}

Often in zooxanthellate genera such as ''Zoanthus'' and ''Palythoa'' there are a large number of different morphs of the same or similar species. Such zooxanthellate genera derive a large portion of their energy requirements from symbiotic dinoflagellates of the genus ''Symbiodinium'' (zooxanthellae), similar to many corals, anemones, and some other marine invertebrates.{{Citation needed|date=January 2025}}

==Families and genera== The families and genera within the order Zoanthin(i)aria/Zoantharia/Zoanthidea are:<ref>{{cite WoRMS|author=WoRMS|year=2018|title=Zoanthidea|id=16327|access-date=2018-08-24}}</ref> * Abyssoanthidae<ref>{{cite WoRMS|author=Reimer, J.|year=2011|title=Abyssoanthidae|id=411554|access-date=2011-12-16}}</ref> ** ''Abyssoanthus'' Reimer & Fujiwara in Reimer, Sinniger, Fujiwara, Hirano & Maruyama, 2007 Suborder Macrocnemina * Epizoanthidae<ref>{{cite WoRMS|author=Reimer, J.|year=2011|title=Epizoanthidae|id=100688 |access-date=2016-09-24}}</ref> ** ''Epizoanthus'' Gray, 1867 ** ''Paleozoanthus'' Carlgren, 1924 ** ''Thoracactis'' Gravier, 1918 * Hydrozoanthidae<ref>{{cite WoRMS|author=Reimer, J.|year=2011|title=Hydrozoanthidae|id=467537|access-date=2011-12-16}}</ref> ** ''Hydrozoanthus'' Sinniger, Reimer & Pawlowski, 2010 ** ''Terrazoanthus'' Reimer & Fujii, 2010 * Microzoanthidae ** ''Microzoanthus'' Fujii & Reimer, 2011 * Nanozoanthidae ** ''Nanozoanthus'' Fujii & Reimer, 2013 * Parazoanthidae<ref>{{cite WoRMS|author1=Sinniger, F.|author2=Reimer, J.|year=2013|title=Parazoanthidae|id=100689|access-date=2016-09-24}}</ref> **''Antipathozoanthus'' Sinniger, Reimer & Pawlowski, 2010 **''Bergia'' Duchassaing & Michelotti, 1860 **''Bullagummizoanthus'' Sinniger, Ocaña & Baco, 2013 **''Corallizoanthus'' Reimer in Reimer Nonaka Sinniger & Iwase, 2008 **''Hurlizoanthus'' Sinniger, Ocaña & Baco, 2013 **''Isozoanthus'' Carlgren, 1905 **''Kauluzoanthus'' Sinniger, Ocaña & Baco, 2013 **''Kulamanamana'' Sinniger, Ocaña & Baco, 2013 **''Mesozoanthus'' Sinniger & Haussermann, 2009 **''Parazoanthus'' Haddon & Shackleton, 1891 **''Savalia'' Nardo, 1814 (synonym: ''Gerardia'') **''Umimayanthus'' Montenegro, Sinniger & Reimer, 2015 **''Zibrowius'' Sinniger, Ocaña & Baco, 2013 Suborder Brachycnemina * Neozoanthidae<ref>{{cite WoRMS|author=Reimer, J.|year=2011|title=Neozoanthidae|id=266944|access-date=2011-12-16}}</ref> ** ''Neozoanthus'' * Sphenopidae<ref>{{cite WoRMS|author=Reimer, J.|year=2011|title=Sphenopidae|id=266945|access-date=2016-09-24}}</ref> ** ''Palythoa'' Lamouroux, 1816 ** ''Sphenopus'' Steenstrup, 1856 * Zoanthidae<ref>{{cite WoRMS|author=Reimer, J.|year=2011|title=Zoanthidae|id=100690|access-date=2016-09-24}}</ref> ** ''Acrozoanthus'' Saville-Kent, 1893 ** ''Isaurus'' Gray, 1828 ** ''Zoanthus'' Cuvier, 1800

Note: there are some zoanthid genera such as ''Neozoanthus'' or ''Paleaozoanthus'' for which there are currently only few data available, those zoanthids having never been found again since their original description.{{Citation needed|date=January 2025}}

==Aquaria== [[File:Zoanthus-dragon-eye.jpg| right|thumb|This dragon-eye zoanthid is a popular source of color in reef tanks]] Zoanthidae include many species popular in the fishkeeping world, among hobbyists and professionals. They are relatively easy to keep alive and healthy, and will often spread to cover rocks in their bright circles of color. They are known by some as carpet coral, button polyps, and "zoas" or "zoos."{{Citation needed|date=January 2025}}

==Captive propagation==

thumb|Eagle Eye zooanthid coral, propagated in captivity

Animals of this order are propagated in captivity by cutting the polyps apart using a scalpel or scissors then attaching to a surface with cyanoacrylate glue. Gloves and goggles should be worn during this process. Drying the polyps with paper towel then gluing them to a small base with gelled cyanoacrylate glue ensures they do not drift in the aquarium when reintroduced.<ref>{{Cite episode |title=Zoanthid and Palythoa Coral Propagation| url=https://www.youtube.com/watch?v=pe0AJVpl480&ab_channel=TidalGardens |archive-url=https://ghostarchive.org/varchive/youtube/20211222/pe0AJVpl480 |archive-date=2021-12-22 |url-status=live| series=Tidal Gardens}}{{cbignore}}</ref>

==Toxicity== Some (but not all) members of this order contain the highly toxic substance palytoxin. Even in small quantities, palytoxin can be incapacitating or potentially fatal.<ref>{{cite web |title=Palytoxin |website=cbwinfo.com |url=http://www.cbwinfo.com/Biological/Toxins/Palytoxin.html |access-date=12 January 2022 |archive-url=https://web.archive.org/web/20090317031203/http://www.cbwinfo.com/Biological/Toxins/Palytoxin.html |archive-date=17 March 2009 }}</ref> A 2010 study found toxic species for sale in three Washington, D.C. area aquarium stores.<ref>{{cite journal |last1=Deeds |first1=J.R. |last2=Handy |first2=S.M. |last3=White |first3=K.D. |last4=Reimer |first4=J.D. |year=2011 |title=Palytoxin found in palythoa sp. zoanthids (Anthozoa, Hexacorallia) sold in the home aquarium trade |journal=PLoS One |volume=6 |issue=4 |article-number=e18235 |doi=10.1371/journal.pone.0018235 |pmid=21483745 |doi-access=free |pmc=3070722 |bibcode=2011PLoSO...618235D }}</ref>

Reports are varied and conflicting on the potential dangers of handling the animal in the aquarist hobby. General opinion and practical experience holds that in order for this toxin to be dangerous to humans, the average aquarist would need to expose mucous membranes or freshly lacerated skin to the polyps, and average handling, propagation and aquarium maintenance is unlikely to pose any danger beyond a localized skin reaction.<ref>{{cite web |title=Some zoanthids produce a deadly toxin |department=Handling zoanthids |website=Blue Zoo Aquatics (bluezooaquatics.com) |series=informational resource |url=http://www.bluezooaquatics.com/resources.asp?show=16 }}</ref>

Other sources state that palytoxin can be absorbed through intact skin,<ref>{{cite journal |first1=Sean Patrick |last1=Nordt |first2=Jerry |last2=Wu |first3=Stephen |last3=Zahller |first4=Richard F. |last4=Clark |first5=F. Lee |last5=Cantrell |year=2009 |title=Palytoxin poisoning after dermal contact with zoanthid coral |journal=Journal of Emergency Medicine |volume=40 |issue=4 |pages=397–399 |doi=10.1016/j.jemermed.2009.05.004 |pmid=19545971 |type=in press }}</ref> and the danger of acute poisonings is quite real. According to a published case report a hobbyist was poisoned through skin injuries on fingers by a species of ''Parazoanthus'', but recovered after three days. His zoanthid was found to contain 2-3 milligrams of PTX per gram.<ref>{{cite journal |first1=Katrin |last1=Hoffmann |first2=Maren |last2=Hermanns-Clausen |first3=Claus |last3=Buhl |first4=Markus W. |last4=Büchler |first5=Peter |last5=Schemmer |first6=Dietrich |last6=Mebs |first7=Silke |last7=Kauferstein |year=2008 |title=A case of palytoxin poisoning due to contact with zoanthid corals through a skin injury |journal=Toxicon |volume=51 |issue=8 |pages=1535–1537 |doi=10.1016/j.toxicon.2008.03.009 |pmid=18433818 |bibcode=2008Txcn...51.1535H }}</ref>

Research suggests that in sublethal quantities, palytoxin is a tumor promoter.<ref>{{cite journal |first=Elizabeth V. |last=Wattenberg |year=2007 |title=Palytoxin: Exploiting a novel skin tumor promoter to explore signal transduction and carcinogenesis |journal=American Journal of Physiology. Cell Physiology |volume=292 |issue=1 |pages=C24–C32 |doi=10.1152/ajpcell.00254.2006 |pmid=16855216 |pmc=1769420 }}</ref>

Generally speaking, it is considered proper practice to always wear appropriate protective gloves and goggles when working on an aquarium.<ref>{{cite magazine |first=Nicholas |last=Violand |date=May 2008 |title=Palytoxin and you: How and why to avoid a deadly zoanthid toxin |page=122 |department=Aquarium science |magazine=Tropical Fish Hobbyist Magazine |url=https://www.tfhmagazine.com/articles/saltwater/aquarium-science-palytoxin-and-you-how-and-why-to-avoid-a-deadly-zoanthid-toxin |url-status=live |access-date=2025-08-05 |via=tfhmagazine.com }}</ref>

==Diet== Zoanthids feed both by photosynthesis, aided by the zooxanthellae they contain, and by capturing plankton and particulate matter. Although photosynthesis aids in their nutrition, even species that do not actively capture plankton cannot live through photosynthesis alone.<ref name="Borneman">{{cite book | last = Borneman | first = Eric H. | title = Aquarium Corals: Selection, Husbandry, and Natural History | publisher = T.F.H. Publications | year =2001 | location =Neptune City, NJ | isbn = 1-890087-47-5 | page = 464}}</ref> Zoanthids are often fed brine shrimp or krill when kept in aquariums for this very reason.

==References== {{Reflist}}

==External links== {{Commons category|Zoantharia}} * [https://web.archive.org/web/20100317051815/http://www.thesea.org/zoanthids/index.html Maintaining Zoanthids Tips, Care, Photos] * [http://reefcentral.com/forums/showthread.php?s=&threadid=158730 Discussion About The Toxicity of Zoanthids] * [https://web.archive.org/web/20110127185635/http://www.zoaid.com/index.php?module=Gallery2&func=main&g2_view=core.ShowItem&g2_itemId=15 Gallery of Zoanthid Pictures] * [http://blogs.discovermagazine.com/notrocketscience/2011/04/05/world's-2nd-deadliest-poison-in-an-aquarium-store-near-you/ World's 2nd deadliest poison, in an aquarium store near you] {{Webarchive|url=https://web.archive.org/web/20110406024238/http://blogs.discovermagazine.com/notrocketscience/2011/04/05/world%E2%80%99s-2nd-deadliest-poison-in-an-aquarium-store-near-you/ |date=2011-04-06 }}

Category:Zoantharia Category:Hexacorallia Category:Anthozoa orders