''Tripodichthys'' 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, the triplespines or tripodfishes. The three species in this genus are found in the Indian Ocean and the western Pacific Ocean in shallow water over soft substrates.

Taxonomy

''Tripoichthys'' was first proposed as a genus in 1968 by the American

ichthyologist Ichthyology is the branch of zoology devoted to the study of fish, including bony fish (Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). According to FishBase, 35,800 species of fish had been described as of March 2 ...

James C. Tyler with ''Triacanthus blochii'' designatedas 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 ...

.''T. blochii'' had originally been described in 1852 by the Dutch ichthyologist

Pieter Bleeker Pieter Bleeker (10 July 1819 – 24 January 1878) was a Dutch medical doctor, Ichthyology, ichthyologist, and Herpetology, herpetologist. He was famous for the ''Atlas Ichthyologique des Indes Orientales Néêrlandaises'', his monumental work on ...

with its type locality given as

Singapore Singapore, officially the Republic of Singapore, is an island country and city-state in Southeast Asia. The country's territory comprises one main island, 63 satellite islands and islets, and one outlying islet. It is about one degree ...

. ''Tripodichthys'' is vlassified within the family Triacanthidae and, in 1968, Tyler classified this family 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 ...

Species

''Tripodichthys'' currently contains the following three valid species: * '' Tripodichthys angustifrons'' Hollard, 1854 (Black-flag tripodfish) * '' Tripodichthys blochii'' (Bleeker, 1852) (Long-tail tripodfish) * '' Tripodichthys oxycephalus'' (Bleeker, 1851) (Short-tail tripodfish)

Etymology

''Tripodichthys'' suffixes the Greek word for "fish", ''-ichthys'' onto ''tripodis'', which means a

tripod A tripod is a portable three-legged frame or stand, used as a platform for supporting the weight and maintaining the stability of some other object. The three-legged (triangular stance) design provides good stability against gravitational loads ...

, as it was envisioned that the fish rested on the subtrate using the two 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 ...

and the lower lobe of 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 ...

. The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

of the

honours

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 ...

, the describer of '' Triacanthus biaculeatus'' which was thought to be a

congeneric Congener may refer to: * Congener (biology), organisms within the same genus * Congener (chemistry), related chemicals, e.g., elements in the same group of the periodic table * Congener (beverages), a substance other than ethanol produced during t ...

with ''T. blochii''. The specific name of ''T. angustifrons'' means "narrow forehead" and refers to this species thinner snout than '' Triacanthus brevirostris'', its assumed congener. The third species has the specific name ''oxycephalus'', meaning "sharp head", an allusion to the long, pointed head.

Characteristics

''Tripodichthys'' tripodfishes are characterised by having a scale covered part 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 ...

which tapers towards the rear. The second spine in 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 ...

is clearly less than half the kength of the first spine and the base of the dorsal fins have a total length which is 1.5 to 1.7 times longer than the base of 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 a low, cruciform ridge on them. In ''T. oxycephalus'' the pelvis is wide between bases of the pelvic fin spines and the

caudal peduncle 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 ...

is short. In the other two species the pelvis is thin between the bases of the pelvic fin spines and they have a long caudal peduncle. In ''T. agustifrons'' the membrane of the spiny dorsal fin is typically dark between the first four spines, there are 22-24 soft rays in the second dorsal fin and 18-19 in the

. In ''T. blochii'' the spiny dorsal fin has a pale membrane, there are 20-24 soft rays in the second dorsal in and 13-15 in the anal fin. These fishes have 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 , in the case of ''T. angustifrons'' and ''T. oxtcephalus'', and in ''T. blochii''.

Distribution and habitat

''Tripodichthys'' tripodfishes are found in the Indian and Western Pacific Oceans. ''T. angustifrons'' has been recorded from Indonesia and northern Australia, ''T. blochii'' from the

South China Sea The South China Sea is a marginal sea of the Western Pacific Ocean. It is bounded in the north by South China, in the west by the Indochinese Peninsula, in the east by the islands of Taiwan island, Taiwan and northwestern Philippines (mainly Luz ...

and Indonesia, with strays recorded in China and Japan, while ''T. oxycephalus'' from the

Bay of Bengal The Bay of Bengal is the northeastern part of the Indian Ocean. Geographically it is positioned between the Indian subcontinent and the Mainland Southeast Asia, Indochinese peninsula, located below the Bengal region. Many South Asian and Southe ...

, South China Sea and

Arafura Sea The Arafura Sea (or Arafuru Sea) lies west of the Pacific Ocean, overlying the continental shelf between Australia and Western New Guinea (also called Papua), which is the Indonesian part of the Island of New Guinea. Geography The Arafura Sea is ...

. They are found at depths down to over sand and mud substrates.

References

{{Taxonbar, from=Q130477 Triacanthidae Marine fish genera Taxa named by James C. Tyler