''Phyllodiscus'' is a

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

sea anemone Sea anemones are a group of predation, predatory marine invertebrates of the order (biology), order Actiniaria. Because of their colourful appearance, they are named after the ''Anemone'', a terrestrial flowering plant. Sea anemones are classifi ...

s in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Aliciidae Aliciidae is a family of sea anemones, comprising the following genera: * '' Alicia'' Johnson, 1861 * '' Cradactis'' McMurrich, 1893 * '' Lebrunia'' Duchassaing de Fonbressin & Michelotti, 1860 * '' Phyllodiscus'' Kwietniewski, 1897 * ''Triactis ...

. The only

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

is ''Phyllodiscus semoni'', commonly known as the night anemone, which is native to shallow seas in the central

Indo-West Pacific The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...

, such as Indonesia, the Philippines and southern Japan. It is venomous and can cause a painful, long-lasting sting to humans. It is called ''unbachi-isoginchaku'' in

Japanese Japanese may refer to: * Something from or related to Japan, an island country in East Asia * Japanese language, spoken mainly in Japan * Japanese people, the ethnic group that identifies with Japan through ancestry or culture ** Japanese diaspor ...

which translates as "wasp-sea anemone".

Description

''Phyllodiscus semoni'' has a broad basal disc attached to the substrate. The lower portion of the column is smooth and the middle section has a radially arranged series of pseudo-tentacles, thick, stalked and branched outgrowths which show great variety in their appearance between different individuals. There are a number of hemispherical vesicles on the branches, and occasionally on the stalks. These contain

nematocyst A cnidocyte (also known as a cnidoblast or nematocyte) is an explosive cell containing one large secretory organelle called a cnidocyst (also known as a cnida () or nematocyst) that can deliver a sting to other organisms. The presence of this ce ...

s containing short and long-shafted stinging threads. The upper section of the column is short and smooth with a few nematocysts. The oral disc has a marginal ring of up to 160 long

tentacle In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work main ...

s, two siphonoglyphs (feeding grooves) and a central mouth.

Behaviour

There are a range of different morphotypes of this sea anemone. Some are smooth discs, some are similar to branching corals and others to dead coral rock covered by algae, resembling these models not only in shape, but also in colour. Some individuals are solitary and others form aggregations of similar morphotypes. The aggregations include a range of different-sized individuals and are likely to be

clones Clone or Clones or Cloning or Cloned or The Clone may refer to: Places * Clones, County Fermanagh * Clones, County Monaghan, a town in Ireland Biology * Clone (B-cell), a lymphocyte clone, the massive presence of which may indicate a pathologi ...

formed by

asexual reproduction Asexual reproduction is a type of reproduction that does not involve the fusion of gametes or change in the number of chromosomes. The offspring that arise by asexual reproduction from either unicellular or multicellular organisms inherit the fu ...

, possibly by fragmentation when the sea anemone moves across the substrate. The different morphotypes show great resemblance to corals, algae and other objects in the environment and the sea anemone seems to use

camouflage Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the ...

mimicry In evolutionary biology, mimicry is an evolved resemblance between an organism and another object, often an organism of another species. Mimicry may evolve between different species, or between individuals of the same species. Often, mimicry f ...

and masquerade to blend itself into its surroundings, deceive potential

prey Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill the ...

and confuse potential predators. ''Phyllodiscus semoni'' is a

zooxanthellate Zooxanthellae is a colloquial term for single-celled dinoflagellates that are able to live in symbiosis with diverse marine invertebrates including demosponges, corals, jellyfish, and nudibranchs. Most known zooxanthellae are in the genus ''Sy ...

species of sea anemone, housing

symbiotic Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasit ...

photosynthetic

dinoflagellate The dinoflagellates (Greek δῖνος ''dinos'' "whirling" and Latin ''flagellum'' "whip, scourge") are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered algae. Dinoflagellates are ...

s within its tissues. These are concentrated in the pseudotentacles which are spread out widely during the day to maximise their exposure to the light. At the same time the oral disc, mouth, and tentacles are retracted into the interior of the animal and it is not apparent that it is a sea anemone at all. At night the oral disc emerges and the tentacles expand to feed on

zooplankton Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...

and small

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

Venom

This sea anemone is venomous and its stings can cause painful injuries to humans, and on rare occasions can result in acute kidney damage. The toxin has been shown to kill the shrimp ''

Palaemon paucidens ''Palaemon paucidens'' is a species of shrimp of the family Palaemonidae. It is found in rivers on the Korean Peninsula Korea ( ko, 한국, or , ) is a peninsular region in East Asia. Since 1945, it has been divided at or near the 38th ...

'' and cause

haemolysis Hemolysis or haemolysis (), also known by several other names, is the rupturing (lysis) of red blood cells (erythrocytes) and the release of their contents (cytoplasm) into surrounding fluid (e.g. blood plasma). Hemolysis may occur in vivo ...

in sheep

red blood cell Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek ''erythros'' for "red" and ''kytos'' for "holl ...

s. Human contact with ''Phyllodiscus semoni'' can cause a severe

dermatitis Dermatitis is inflammation of the skin, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened. The area of skin involved can v ...

with ulceration and swelling of the affected part which may persist for months. Several

haemolytic Hemolysis or haemolysis (), also known by several other names, is the rupturing (lysis) of red blood cells (erythrocytes) and the release of their contents (cytoplasm) into surrounding fluid (e.g. blood plasma). Hemolysis may occur in vivo o ...

toxins have been isolated from ''Phyllodiscus semoni'' and it is the first sea anemone whose venom has been shown to damage the kidneys and cause acute

renal failure Kidney failure, also known as end-stage kidney disease, is a medical condition in which the kidneys can no longer adequately filter waste products from the blood, functioning at less than 15% of normal levels. Kidney failure is classified as eit ...

. The venom does not appear to affect other major organs.

References

{{Taxonbar, from=Q15646574 Aliciidae Monotypic cnidarian genera Hexacorallia genera