| Palythoa | |
|---|---|
 | |
| Palythoa grandis | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Cnidaria |
| Class: | Anthozoa |
| Order: | Zoantharia |
| Family: | Sphenopidae |
| Genus: | Palythoa Lamouroux, 1816 |
| Synonyms | |
| |
Palythoa is a genus of anthozoans in the order Zoantharia. [1] [2]
The polyps of Palythoa are partially embedded in an encrusting mat of tissue (coenenchyme) covering the substrate on which the colony grows. The individual polyps have flattened oral discs surrounded by a fringe of tentacles. The tentacles' shape and size can vary considerably between species, and even between colonies of the same species. Their colors are also highly variable, with relatively dull shades like cream, coffee, white, brown, or yellow, being the most common. Fluorescent colored colonies also exist, but these are more rare. [3] [4]
Palytoxin is a highly toxic fatty alcohol produced by many species of Palythoa, and is also found in other corals and certain marine invertebrates. The substance was first isolated from the seaweed-like "limu-make-o-Hana" ("Seaweed of Death from Hana") in 1971 in Hawaii. Scientific investigation of the seaweed found it to be a colonial cnidarian, which was classified as a zoanthid and named Palythoa toxica . Small quantities of palytoxin can be fatal should it be ingested or inhaled.
The presence of this toxin is of significance to aquarists who keep reef aquariums, as Palythoa and related zoanthids are commonly kept as decorative specimens in marine aquaria. Aquarists have reported symptoms consistent with palytoxin poisoning prior to having exposure to zoanthids suspected to contain the toxin. One report involved an aquarist being accidentally poisoned through skin injuries after handling zoanthids. [5] Another report involved an aquarium hobbyist in Virginia who experienced a severe respiratory reaction after trying to eradicate colonies of brown zoanthids (suspected to be Palythoa) from rocks in their aquarium. [6] A 2010 study found that a single specimen of Palythoa from a sample of fifteen colonies purchased from three aquarium stores in the Washington D.C. area contained high levels of palytoxin, indicating that toxic individuals are present in the captive population. [7]
While poisoning events have occurred, they are exceedingly rare, and many reef hobbyists have kept Palythoa without any adverse reactions. However, it is generally recommended to always wear appropriate protective gloves and goggles when reaching into aquaria and handling animals which are suspected to be toxic. [8]
The genus Protopalythoa was once thought to be distinct from the genus Palythoa but is now considered to be a synonym. [1]
The following species are recognized in the genus Palythoa:
¹Indicates Species Unreviewed: has not been verified by a taxonomic editor
Taxon inquirendum:
Palytoxin, PTX or PLTX is an intense vasoconstrictor, and is considered to be one of the most poisonous non-protein substances known, second only to maitotoxin in terms of toxicity in mice.
Zoanthids are an order of cnidarians 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 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.
Nassarius, common name nassa mud snails (USA) or dog whelks (UK), is a genus of minute to medium-sized sea snails, marine gastropod molluscs in the family Nassariidae. They are scavengers.
Aiptasia is a genus of a symbiotic cnidarian belonging to the class Anthozoa. Aiptasia is a widely distributed genus of temperate and tropical sea anemones of benthic lifestyle typically found living on mangrove roots and hard substrates. These anemones, as well as many other cnidarian species, often contain symbiotic dinoflagellate unicellular algae of the genus Symbiodinium living inside nutritive cells. The symbionts provide food mainly in the form of lipids and sugars produced from photosynthesis to the host while the hosts provides inorganic nutrients and a constant and protective environment to the algae. Species of Aiptasia are relatively weedy anemones able to withstand a relatively wide range of salinities and other water quality conditions. In the case of A. pallida and A. pulchella, their hardiness coupled with their ability to reproduce very quickly and out-compete other species in culture gives these anemones the status of pest from the perspective of coral reef aquarium hobbyists. These very characteristics make them easy to grow in the laboratory and thus they are extensively used as model organisms for scientific study. In this respect, Aiptasia have contributed a significant amount of knowledge regarding cnidarian biology, especially human understanding of cnidarian-algal symbioses, a biological phenomenon crucial to the survival of corals and coral reef ecosystems. The dependence of coral reefs on the health of the symbiosis is dramatically illustrated by the devastating effects experienced by corals due to the loss of algal symbionts in response to environmental stress, a phenomenon known as coral bleaching.
Natica is a genus of small to medium-sized predatory sea snails, marine gastropods in the subfamily Naticinae of the family Naticidae, the moon snails. The genus was erected by Giovanni Antonio Scopoli in 1777.
Parazoanthus is a genus of anemone-like anthozoans in the order Zoantharia.
Actinia is a genus of sea anemones in the family Actiniidae. Actinia display a rare form of heteromorphosis in which a cut inflicted on a specimen can develop into a second mouth.
Sagartia is a genus of sea anemones in the family Sagartiidae. The genus was first described by Philip Henry Gosse in 1855 and the image is his painting of several species found in British waters included in his book, A history of the British sea-anemones and corals.
Zoanthus is a genus of anthozoans in the family Zoanthidae. It is the type genus for its family and order.
Anemonia is a genus of sea anemones belonging to the family Actiniidae.
Palythoa toxica, also referred to by its Hawaiian common name, limu-make-o-Hana, is a species of zoanthid native to Hawaii. It is notable as the species in which palytoxin was discovered and from which it was first isolated.
Parazoanthus darwini is a species of macrocnemic zoanthid first found in the Galapagos. It can be distinguished by its association with sponges, by having about 24–30 tentacles and polyps embedded in a well-developed coenenchyme.
Briareum is a genus of soft corals in the family Briareidae. The coral is cultivated by aquarium owners for its fluorescing polyps, which reveal themselves under actinic light. The genus is in need of extensive examination, as many specimens sold by marketers display unique and similar characteristics, but are often labeled as one species, Pachyclavularia violacea.