''Triacanthus'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of marine

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...

belonging to the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Triacanthidae Triacanthidae, the triplespines or tripodfishes, is a family of marine ray-finned fishes belonging to the order Tetraodontiformes, which also includes the pufferfishes, boxfishes, filefishes and related groups. The family is made up of four exta ...

, the triplespines or tripodfishes. The two species in this genus are found in the Indian Ocean and the western Pacific Ocean.

Taxonomy

''Triacanthus'' was first proposed as a

monospecific genus 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 "unispe ...

in 1786 by the German

naturalist Natural history is a domain of inquiry involving organisms, including animals, fungi, and plants, in their natural environment, leaning more towards observational than experimental methods of study. A person who studies natural history is cal ...

Lorenz Oken Lorenz Oken (1 August 1779 – 11 August 1851) was a Germans, German natural history, naturalist, botany, botanist, biologist, and ornithology, ornithologist. Biography Oken was born Lorenz Okenfuss () in Bohlsbach (now part of Offenburg), Ortena ...

with ''Balistes biaculeatus'' as its

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

monotypy 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 "unispe ...

. ''B. aculeatus'' was first formally described in 1786 by the German

physician A physician, medical practitioner (British English), medical doctor, or simply doctor is a health professional who practices medicine, which is concerned with promoting, maintaining or restoring health through the Medical education, study, Med ...

and naturalist

Marcus Elieser Bloch Marcus Elieser Bloch (1723–1799) was a German physician and naturalist who is best known for his contribution to ichthyology through his multi-volume catalog of plates illustrating the fishes of the world. Brought up in a Hebrew-speaking Jewish ...

with its type locality given as the Indian Ocean. In 1968, James C. Tyler classified the family Triacanthidae within the

suborder Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized ...

Triacanthoidei alongside the Triacanthodidae. The 5th edition of ''

Fishes of the World ''Fishes of the World'' is a standard reference for the systematics of fishes. It was first written in 1976 by the American ichthyologist Joseph S. Nelson (1937–2011). Now in its fifth edition (2016), the work is a comprehensive overview of t ...

'' classifies the Triacanthoidei as suborder of the

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

Tetraodontiformes Tetraodontiformes (), also known as the Plectognathi, is an order of ray-finned fishes which includes the pufferfishes and related taxa. This order has been classified as a suborder of the order Perciformes, although recent studies have found ...

Etymology

''Triacanthus'' prefixes ''acanthus'', which means “thorn” or “spine”, with ''tri-'', meaning “three”, this is an allusion to the long and robust first spine of the

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

and the two large spines in the

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral (belly) surface of fish, and are the lower of the only two sets of paired fins (the other being the laterally positioned pectoral fins). The pelvic fins are homologous to the hi ...

s. ''

Balistes ''Balistes'' is a genus of marine Actinopterygii, ray-finned fishes belonging to the Family (biology), family Balistidae, the triggerfishes. The triggerfishes in this genus are found in the Atlantic and eastern Pacific Ocean. Taxonomy ''Balistes ...

'', the genus the type species was originally classified in, does not possess pelvic fin spines.

Species

''Triacanthus'' currently has 2 recognised species classified within it: * ''

Triacanthus biaculeatus ''Triacanthus biaculeatus'', also known as the short-nosed tripod fish, black-finned triple-spine, blacktail tripodfish, hollow-snouted tripodfish or silver tripodfish, is a species of marine ray-finned fish belonging to the family Triacanthidae ...

'' (Bloch, 1786) (Short-nosed tripodfish) * '' Triacanthus nieuhofii'' Bleeker, 1852 (Silver tripodfish)

Characteristics

''Triacanthus'' tripodfishes have a lower, scaly surface of the

pelvis The pelvis (: pelves or pelvises) is the lower part of an Anatomy, anatomical Trunk (anatomy), trunk, between the human abdomen, abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also c ...

that is nearly as wide at the front as it is at the rear and which does not taper to a point. There are six spines in the dorsal fin, the first spine being between three and four times longer than the second spine. There are 21 to 26 soft rays in the dorsal fin and 17 to 23 in the

anal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported o ...

. The scales have low emarginated cross-shaped ridges. The two species in the genus are similar in size with maximum published total lengths for ''T. biaculeatus'' of and for ''T. nieuhofii'' of .

Distribution and habitat

''Triacanthus'' tripodfishes have an

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 s ...

distribution and are found in the

Persian Gulf The Persian Gulf, sometimes called the Arabian Gulf, is a Mediterranean seas, mediterranean sea in West Asia. The body of water is an extension of the Arabian Sea and the larger Indian Ocean located between Iran and the Arabian Peninsula.Un ...

and

Gulf of Oman The Gulf of Oman or Sea of Oman ( ''khalīj ʿumān''; ''daryâ-ye omân''), also known as Gulf of Makran or Sea of Makran ( ''khalīj makrān''; ''daryâ-ye makrān''), is a gulf in the Indian Ocean that connects the Arabian Sea with th ...

east to Indonesia, north to Japan and south to northern Australia. These fishes are found in coastal waters and estuaries, on sand or mud flats typically no deeper than .

Human utilisation

''Triacanthus'' tripodfishes are sold as fresh fish in markets and are used in

traditional Chinese medicine Traditional Chinese medicine (TCM) is an alternative medicine, alternative medical practice drawn from traditional medicine in China. A large share of its claims are pseudoscientific, with the majority of treatments having no robust evidence ...

References

{{Taxonbar, from=Q130071 Triacanthidae Marine fish genera Taxa named by Lorenz Oken