The giant African threadfin (''Polydactylus quadrifilis'') is a species of

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or hor ...

from the

threadfin Threadfins are silvery grey perciform fish of the family Polynemidae. Found in tropical to subtropical waters throughout the world, the threadfin family contains eight genera and about 40 species. An unrelated species sometimes known by the name ...

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 ...

Polynemidae Threadfins are silvery grey perciform fish of the family Polynemidae. Found in tropical to subtropical waters throughout the world, the threadfin family contains eight genera and about 40 species. An unrelated species sometimes known by the name ...

. It is found in the eastern Atlantic Ocean off the west coast of Africa.

Description

The giant African threadfin is, as its common name indicates, a large species of threadfin attaining a maximum

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

of , although the more common size is . It has a pointed snout and analmost straight dorsal profile on the head. It has two separate

dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through conv ...

s, the first dorsal fin has 8 spines with the second of these being thicker than the rest, and the second dorsal fin contains a single spine and 13 soft rays. The

anal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

has 3 spines and 11 soft rays, its base approximately equal in length to the base of the second dorsal fin. The

pectoral fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

has 12 or 13 unbranched rays and it measures 20 to 24% of the

standard length Fish measurement is the measuring of individual fish and various parts of their anatomies. These data are used in many areas of ichthyology, including taxonomy and fisheries biology. Overall length * Standard length (SL) is the length of a fish m ...

of the fish, its tip not extended as far as the tip of

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral surface of fish. The paired pelvic fins are homologous to the hindlimbs of tetrapods. Structure and function Structure In actinopterygians, the pelvic fin consists of two en ...

. There are 4 pectoral filaments with the first being the shortest, the first three filaments extend past the origin of the pelvic fin but not as far as its tip. The fourth pectoral filament is the longest, being 27 to 39% of the standard length, reaches at least to the tip of the pelvic fin. The

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

is deeply forked and has lobes non-filamentous long lobes. There are 70*71 pored scales in the

lateral line The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelial ...

which is simple and runs from the upper end of the gill slit to the upper end of the lower lobe of the caudal fin. The head and upper flanks are silver with a blackish tint, paler on the lower flanks and white on the breast and belly. The snout is semi-transparent. The dorsal fins and caudal fin are pale with blackish rear margins. The pectoral fin is bright yellow and the pectoral filaments are white. The pelvic and anal fins are dusky with white on the front edge and at their bases.

Distribution

The giant African threadfin occurs in the tropical eastern Atlantic Ocean off the coast of western Africa from Senegal to Congo. There is a single record from Mauritania.

Habitat and biology

The giant African threadfin is found in shallow coastal waters where there are sandy and muddy bottoms and is occasionally recorded in brackish waters. It will enters estuaries and is rarely taken in fresh water but the largest individuals are only recorded from marine waters. This carnivorous fish east crustaceans and fishes.

Fisheries

The giant African threadfin is a highly sought after species for commercial and sport fisheries.

Species description

The giant African threadfin was first formally described by Georges Cuvier in ''Histoire naturelle des poissons. Tome troisième. Suite du Livre troisième. Des percoïdes à dorsale unique à sept rayons branchiaux et à dents en velours ou en cardes'' co-authored with

Achille Valenciennes Achille Valenciennes (9 August 1794 – 13 April 1865) was a French zoologist. Valenciennes was born in Paris, and studied under Georges Cuvier. His study of parasitic worms in humans made an important contribution to the study of parasitology. ...

. The name Cuvier gave it was ''Polynemus quadrifilis'' and the type locality was given as Senegal.

References

{{DEFAULTSORT:Giant African Threadfin Giant African threadfin Fish described in 1829 Taxa named by Georges Cuvier