Triacanthoidei is a

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 ...

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

belonging to 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 ...

, which includes the pufferfishes, triggerfishes and related taxa. These benthic fishes are mainly found in the Indian Ocean with some of the spikefishes found in the Western Atlantic Ocean.

Taxonomy

Triacanthoidei was first proposed as a superfamily, the Triacanthoidea, in 1968 by the American ichthyologist James C. Tyler who placed it in the monotypic suborder Triacanthoidei. The 5th edition of ''Fishes of the World'' does not use the superfamily classification for this taxon, listing only the suborder and its constituent families within the order Tetraodontiformes.

Etymology

Triacanthoidei has its base in the name of the genus '' Triacanthus'' which prefixes ''acanthus'', meaning "thorn" or "spine" with ''tri'' , which means "three". This is a reference too the large 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 ...

. The element ''oid'' is a contraction of ''oides'' which ''means "resembles".

Families

Triaconthoidei contains the following families: *Family Triacanthodidae

Gill A gill () is a respiration organ, respiratory organ that many aquatic ecosystem, aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow r ...

, 1862 (Spikefishes) **Subfamily Hollardiinae Tyler, 1968 **Subfamily Triacanthodinae Gill, 1862 *Family

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 ...

Bleeker, 1859 (Triplespines)

Characteristics

Triacanthoidei has been resolved as a monophyletic group and the two families share the some basal features. These include a dorsal nerve cord which is not greatly shortened, a large spine, and 2 soft rays, in the pelvic fins the spine can be locked into position. They also have a slightly protractible upper jaw, there are six spines in the dorsal fin and 12 main fin rays in the

caudal 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 only ...

. They have between 2 and 6 separate with 12 principal rays. The largest species in the group are ''

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 ...

'' and Trixiphichthys weberi both with maximum published

total length Fish measurement is the measuring of individual fish and various parts of their anatomies, for data used in many areas of ichthyology, including taxonomy and fishery biology. Overall length Standard length (SL) is the length of a fish measured f ...

s of , while the smallest is '' Atrophacanthus japonicus'' with a maximum published

standard length Fish measurement is the measuring of individual fish and various parts of fish anatomy, their anatomies, for data used in many areas of ichthyology, including Taxonomy (biology), taxonomy and fishery biology. Overall length Standard length (SL) is ...

is .

Distribution and habitat

Triacanthoidei fishes are found mainly in the

Indo-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 ...

region but the family Triacanthodidae gas some species in the Western Atlantic Ocean. The spikefishes are deepwater benthic marine fishes while the triplespines are shallow water, marine benthic fishes.

References

{{Taxonbar, from=Q3538648 Tetraodontiformes Fish suborders Taxa named by James C. Tyler