Palythoa Argus

''Palythoa'' is a genus of anthozoans in the order Zoantharia.Reimer, J. (2018). Palythoa Lamouroux, 1816. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=205785 on 2018-08-27

Description

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.

Palytoxin

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. 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. 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.

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.Nicholas Violan
Aquarium Science: Palytoxin and You
Tropical Fish Hobbyist Magazine

Taxonomy and systematics

The genus ''Protopalythoa'' was once thought to be distinct from the genus ''Palythoa'' but is now considered to be a synonym.

Species

The following species are recognized in the genus ''Palythoa'':

* ''Palythoa aggregata'' Lesson, 1830
* ''Palythoa anneae'' Carlgren, 1938
* ''Palythoa anthoplax'' Pax & Müller, 1957¹
* ''Palythoa arenacea'' Heller, 1868
* ''Palythoa argus'' Ehrenberg, 1834
* ''Palythoa aspera'' Pax, 1909
* ''Palythoa atogrisea'' Pax, 1924
* ''Palythoa australiae'' Carlgren, 1937¹
* ''Palythoa australiensis'' Carlgren, 1950
* ''Palythoa bertholeti'' Gray, 1867
* ''Palythoa brasiliensis'' Heider, 1899
* ''Palythoa braunsi'' Pax, 1924
* ''Palythoa brochi'' Pax, 1924
* ''Palythoa buitendijkl'' Pax, 1924
* ''Palythoa caesia'' Dana, 1846
* ''Palythoa calcaria'' Muller, 1883
* ''Palythoa calcigena'' Pax, 1924
* ''Palythoa calycina'' Pax, 1909
* ''Palythoa canalifera'' Pax, 1908
* ''Palythoa canariensis'' Haddon & Duerden, 1896
* ''Palythoa cancrisocia'' Martens, 1876
* ''Palythoa capensis'' Haddon & Duerden, 1896¹
* ''Palythoa caracasiana