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| Zoanthids | |
|---|---|
 | |
| Parazoanthus axinellae | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Cnidaria |
| Subphylum: | Anthozoa |
| Class: | Hexacorallia |
| Order: | Zoantharia |
| Diversity | |
| See text. | |
Zoanthids (also known as:zoanthiniarians,zoantharians (proper),colonial anemones,button polyps; scientific names:Zoanthiniaria,[1]Zoanthinaria,[2]Zoantharia,[3]Zoanthidea,[4]Zoanthidia,[5]Zoantharida[6]) are anorder ofhexacorals.
Zoanthids are commonly found incoral reefs, the deep sea and many other marine environments around the world. Theseanimals come in a variety of different colonizing formations and in numerous different colors. They can be found as individualpolyps, attached by a fleshystolon or a mat that can be created from small pieces ofsediment, 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 corals inreef aquaria, easily propagating and very durable in many water conditions.
The name Zoantharia (but not the above mentioned variants of this name) is often used as a synonym ofHexacorallia, i. e. in a much broader sense than in this article.
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 familyZoanthidae). A main characteristic of the order is that their tentacles are all marginal. Most species propagateasexually and the offspring of the original polyp remain connected to each other, by astolonal network orcoenosarc. Some species are solitary.[7]
While the most well-known zoanthids are the zooxanthellate genera found in tropical and sub-tropical waters (primarilyZoanthus andPalythoa), many other species and genera exist, some still relatively unknown to science.[8][9][10][11] Many zoanthids (in particular the genera Epizoanthus and Parazoanthus) are often found growing on other marine invertebrates.[citation needed]
Often in zooxanthellate genera such asZoanthus andPalythoa there are a large number of differentmorphs of the same or similar species. Such zooxanthellate genera derive a large portion of their energy requirements from symbioticdinoflagellates of the genusSymbiodinium (zooxanthellae), similar to many corals, anemones, and some other marine invertebrates.[citation needed]
The families and genera within the order Zoanthin(i)aria/Zoantharia/Zoanthidea are:[12]
SuborderMacrocnemina
SuborderBrachycnemina
Note: there are some zoanthid genera such asNeozoanthus orPaleaozoanthus for which there are currently only few data available, those zoanthids having never been found again since their original description.[citation needed]
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]
Zooanthids and Palythoa 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.[20]
Some (but not all) members of this order contain the highly toxic substancepalytoxin. Even in small quantities, palytoxin can be incapacitating or potentially fatal.[21] A 2010 study found toxic species for sale in three Washington, D.C. area aquarium stores.[22]
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.[23]
Other sources state that palytoxin can be absorbed through intact skin,[24] 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 ofParazoanthus, but recovered after three days. His zoanthid was found to contain 2-3 milligrams of PTX per gram.[25]
Research suggests that in sublethal quantities, palytoxin is a tumor promoter.[26]
Generally speaking, it is considered proper practice to always wear appropriate protective gloves and goggles when handling sea invertebrates.[27]
Zoanthids feed both byphotosynthesis, aided by the zooxanthellae they contain, and by capturingplankton and particulate matter. Although photosynthesis aids in their nutrition, even species that do not actively capture plankton cannot live through photosynthesis alone.[28] Zoanthids are often fedbrine shrimp orkrill when kept in aquariums.
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