The African threadfish (''Alectis alexandrina''), also known as the Alexandria pompano, is a

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 ...

of large

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

in the jack family,

Carangidae The Carangidae are a family of ray-finned fish which includes the jacks, pompanos, jack mackerels, runners, and scads. It is the largest of the six families included within the order Carangiformes. Some authorities classify it as the only family ...

. The species is distributed along the coast of tropical

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

in the eastern

Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...

, extending to the

Mediterranean Sea The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the ea ...

. Adults live predominantly in waters shallower than 70 m deep, often forming small schools. The African threadfish is similar in appearance to the closely related and co-occurring African pompano, with the species' most definitive feature its slightly concave head profile. Like other members of the genus ''

Alectis ''Alectis'' is a genus of fish in the family Carangidae containing three extant species, all of which are large marine fishes. They are commonly known as threadfish, diamond trevallies or pompanos, although they have no close affiliation with t ...

'', the juveniles of the species have long trailing dorsal and anal

fin A fin is a thin component or appendage attached to a larger body or structure. Fins typically function as foils that produce lift or thrust, or provide the ability to steer or stabilize motion while traveling in water, air, or other fluids. Fin ...

s. The African threadfish is of minor commercial importance, and is also considered to be a

game fish Game fish, sport fish or quarry refer to popular fish pursued by recreational anglers, and can be freshwater or saltwater fish. Game fish can be eaten after being caught, or released after capture. Some game fish are also targeted commerciall ...

Taxonomy and naming

The African threadfish is one of three members of the diamond trevally

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 ...

'', which is one of 33 genera in the jack and horse mackerel

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 ...

. The Carangidae are part of the

order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...

Carangiformes Carangiformes is an order of the ray-finned fishes. The order is part of a clade which is a sister clade to the Ovalentaria, the other orders in the clade being Synbranchiformes, Anabantiformes, Istiophoriformes and Pleuronectiformes. The Carang ...

. The species has a complex taxonomic history, featuring two

species description A species description is a formal description of a newly discovered species, usually in the form of a scientific paper. Its purpose is to give a clear description of a new species of organism and explain how it differs from species that have be ...

s. The first description was made by the

French French (french: français(e), link=no) may refer to: * Something of, from, or related to France ** French language, which originated in France, and its various dialects and accents ** French people, a nation and ethnic group identified with Franc ...

naturalist

Étienne Geoffroy Saint-Hilaire Étienne Geoffroy Saint-Hilaire (15 April 177219 June 1844) was a French naturalist who established the principle of "unity of composition". He was a colleague of Jean-Baptiste Lamarck and expanded and defended Lamarck's evolutionary theories. ...

in 1817, in which he named the species ''Gallus alexandrinus'', using the generic name '' Gallus'' which had been created by Lacépède after he recognised the genus distinct from ''Zeus'', a genus of

dories A dory is a small, shallow-draft boat, about long. It is usually a lightweight boat with high sides, a flat bottom and sharp bows. It is easy to build because of its simple lines. For centuries, the dory has been used as a traditional fishin ...

. However, ''Gallus'' was preoccupied by a bird, leading to the reassignment of the species to at least six different genera, before the species was placed in ''Alectis''. The second description was made by

Georges Cuvier Jean Léopold Nicolas Frédéric, Baron Cuvier (; 23 August 1769 – 13 May 1832), known as Georges Cuvier, was a French natural history, naturalist and zoology, zoologist, sometimes referred to as the "founding father of paleontology". Cuvier ...

in 1833 under the name of ''Gallichthys aegyptiacus''. This name was also re-evaluated twice, before the description was discarded as a junior synonym of ''A. alexandrina''. The species has also been incorrectly referred to as ''Alectis alexandrinus''. However the genus is feminine and so ''alexandrina'' is the correct spelling. The common names 'African threadfish' and 'Alexandria pompano' are in reference to the species prominent distribution around Africa, as well as the thread like appearance of the juveniles dorsal and anal fins.

Description

The African threadfish has the typical

body Body may refer to: In science * Physical body, an object in physics that represents a large amount, has mass or takes up space * Body (biology), the physical material of an organism * Body plan, the physical features shared by a group of anima ...

structure of a large jack, with a distinctly angular, strongly compressed body. The major identifying feature of the species is its head profile, having a slight concavity near the

eye Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conv ...

s which distinguishes it from the African pompano. The

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal co ...

profile of the fish is more curved than the

ventral Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. Th ...

profile, and the body is deepest between the origins of the soft

and soft

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 ...

s. The first section of the dorsal fin consists of 5 to 7 visible spines, with the second section having one spine and 20 to 22

soft rays Fish anatomy is the study of the form or morphology of fish. It can be contrasted with fish physiology, which is the study of how the component parts of fish function together in the living fish. In practice, fish anatomy and fish physiology co ...

. The anal fin has two spines followed by a single spine and 18 or 19 soft rays. 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 ...

is long and curved, extending beyond the junction of the straight and curved sections of 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 ...

. Anterior to 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 ...

are two oblate keels on each side of the line of scutes. The body appears to be scaleless, but on closer inspection has minute, deeply embedded

scales Scale or scales may refer to: Mathematics * Scale (descriptive set theory), an object defined on a set of points * Scale (ratio), the ratio of a linear dimension of a model to the corresponding dimension of the original * Scale factor, a number w ...

. The lateral line is strongly curved anteriorly, with a section of 6 to 11

scute A scute or scutum (Latin: ''scutum''; plural: ''scuta'' "shield") is a bony external plate or scale overlaid with horn, as on the shell of a turtle, the skin of crocodilians, and the feet of birds. The term is also used to describe the anterior po ...

s toward the tail. Juveniles and often adults have long, filamentous trailing first anal and dorsal fin spines, a trait of all members of ''Alectis''. The species grows to at least 1 m in length. The African threadfish is silver in colour, often with blue and greenish tints and reflection, especially when fresh. The fins are all a pale silvery green to blue colour, or

hyaline A hyaline substance is one with a glassy appearance. The word is derived from el, ὑάλινος, translit=hyálinos, lit=transparent, and el, ὕαλος, translit=hýalos, lit=crystal, glass, label=none. Histopathology Hyaline cartilage is ...

. Juveniles may show two dark bands on their lower bodies.

Distribution and habitat

The African threadfish is primarily distributed throughout the tropical eastern

, inhabiting the waters of

West Africa West Africa or Western Africa is the westernmost region of Africa. The United Nations defines Western Africa as the 16 countries of Benin, Burkina Faso, Cape Verde, The Gambia, Ghana, Guinea, Guinea-Bissau, Ivory Coast, Liberia, Mali, Maurit ...

from

Morocco Morocco (),, ) officially the Kingdom of Morocco, is the westernmost country in the Maghreb region of North Africa. It overlooks the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to ...

around to

Angola , national_anthem = " Angola Avante"() , image_map = , map_caption = , capital = Luanda , religion = , religion_year = 2020 , religion_ref = , coordina ...

. The species also has had several individuals taken from the

Mediterranean The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the e ...

and one extreme capture in the

Adriatic Sea The Adriatic Sea () is a body of water separating the Italian Peninsula from the Balkan Peninsula. The Adriatic is the northernmost arm of the Mediterranean Sea, extending from the Strait of Otranto (where it connects to the Ionian Sea) to t ...

. Adults are generally solitary in

coastal The coast, also known as the coastline or seashore, is defined as the area where land meets the ocean, or as a line that forms the boundary between the land and the coastline. The Earth has around of coastline. Coasts are important zones in n ...

waters, occupying lower parts of the water column, down to at least 70 m. Juveniles are usually

pelagic The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or wa ...

and drift with ocean currents, sometimes ending up in

estuarine An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environment ...

environments.

Biology

Limited information is available on the species

biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary i ...

, with only the

diet Diet may refer to: Food * Diet (nutrition), the sum of the food consumed by an organism or group * Dieting, the deliberate selection of food to control body weight or nutrient intake ** Diet food, foods that aid in creating a diet for weight loss ...

of the species confirmed. The African threadfish feeds on

squid True squid are molluscs with an elongated soft body, large eyes, eight arms, and two tentacles in the superorder Decapodiformes, though many other molluscs within the broader Neocoleoidea are also called squid despite not strictly fitting t ...

and other fishes. The

reproduction Reproduction (or procreation or breeding) is the biological process by which new individual organisms – "offspring" – are produced from their "parent" or parents. Reproduction is a fundamental feature of all known life; each individual or ...

in the species is largely unknown, but observations on ''Alectis ciliaris'' suggest individual fish may pair and then

spawn Spawn or spawning may refer to: * Spawn (biology), the eggs and sperm of aquatic animals Arts, entertainment, and media * Spawn (character), a fictional character in the comic series of the same name and in the associated franchise ** '' Spawn: ...

Relationship to humans

The species is of minor importance to local

fisheries Fishery can mean either the enterprise of raising or harvesting fish and other aquatic life; or more commonly, the site where such enterprise takes place ( a.k.a. fishing ground). Commercial fisheries include wild fisheries and fish farms, both ...

throughout its range, and is also considered a good

, especially in larger sizes. The species is rarely targeted by anglers though, due to its comparative rarity. The fish also fetches high prices at

market Market is a term used to describe concepts such as: *Market (economics), system in which parties engage in transactions according to supply and demand *Market economy *Marketplace, a physical marketplace or public market Geography *Märket, an ...

, unlike many other members of the Carangidae. The

IGFA The International Game Fish Association (''IGFA'') is the leading authority on angling pursuits and the keeper of the most current World Record fishing catches by fish categories. Fishermen who are sport fishers are careful to follow their string ...

world record for the species stands at 8.10 kg (17 lb 3oz) caught off of Daklha,

in 1993.

References

External links

African threadfish (''Alectis alexandrina'')
a
Encyclopaedia of Life
{{Taxonbar, from=Q765602 African threadfish Fish of Africa Fish of the East Atlantic Fish of the Mediterranean Sea Marine fauna of West Africa African threadfish Taxa named by Étienne Geoffroy Saint-Hilaire