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

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of large marine

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

in the jack family,

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

. The species is distributed along the coast of tropical

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

in the eastern

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

, 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 east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern Eur ...

. 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 (biology), family Carangidae containing three Extant taxon, extant species, all of which are large Marine (ocean), marine fishes. They are commonly known as threadfish, diamond trevallies or pompanos, ...

'', 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. F ...

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 species pursued by recreational fishing, recreational fishers (typically angling, anglers), and can be freshwater fish, freshwater or saltwater fish. Game fish can be fish as food, eaten aft ...

Taxonomy and naming

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

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 ...

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

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 ...

. The Carangidae are part 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 ...

Carangiformes Carangiformes is a large, diverse order of ray-finned fishes within the clade Percomorpha. It is part of a sister clade to the Ovalentaria, alongside its sister group, the Anabantaria (including Anabantiformes and Synbranchiformes). The Cara ...

. The species has a complex taxonomic history, featuring two

species description A species description is a formal scientific description of a newly encountered species, typically articulated through a scientific publication. Its purpose is to provide a clear description of a new species of organism and explain how it diff ...

s. The first description was made by the

French French may refer to: * Something of, from, or related to France ** French language, which originated in France ** French people, a nation and ethnic group ** French cuisine, cooking traditions and practices Arts and media * The French (band), ...

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 ...

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 theorie ...

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. 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". Cuv ...

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 anim ...

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 An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system. In higher organisms, the ey ...

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 The fus ...

profile of the fish is more curved than the

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

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

and soft

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 ...

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 moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish aquatic locomotion, swim. Apart from the tail or caudal fin, fish fins have no direct connection with the vertebral column ...

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 epithelia ...

. Anterior to 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 ...

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 ...

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

scute A scute () or scutum (Latin: ''scutum''; plural: ''scuta'' "Scutum (shield), 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 Bird anatomy#Scales, birds. The ter ...

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 , and . Histopathology Hyaline cartilage is named after its glassy appearance on fresh gross pathology. On light microscopy of H&E stained slides, the extracellula ...

. 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, also known as Western Africa, is the westernmost region of Africa. The United Nations geoscheme for Africa#Western Africa, United Nations defines Western Africa as the 16 countries of Benin, Burkina Faso, Cape Verde, The Gambia, Gha ...

from

Morocco Morocco, officially the Kingdom of Morocco, is a country in the Maghreb region of North Africa. It has coastlines on the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to Algeria–Morocc ...

around to

Angola Angola, officially the Republic of Angola, is a country on the west-Central Africa, central coast of Southern Africa. It is the second-largest Portuguese-speaking world, Portuguese-speaking (Lusophone) country in both total area and List of c ...

. 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 east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern ...

and one extreme capture in the

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

. Adults are generally solitary in

coastal A coast (coastline, shoreline, seashore) is the land next to the sea or the line that forms the boundary between the land and the ocean or a lake. Coasts are influenced by the topography of the surrounding landscape and by aquatic erosion, su ...

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. The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or water column between the sur ...

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 environm ...

environments.

Biology

Limited information is available on the species

biology Biology is the scientific study of life and living organisms. It is a broad natural science that encompasses a wide range of fields and unifying principles that explain the structure, function, growth, History of life, origin, evolution, and ...

, 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 A squid (: squid) is a mollusc with an elongated soft body, large eyes, eight cephalopod limb, arms, and two tentacles in the orders Myopsida, Oegopsida, and Bathyteuthida (though many other molluscs within the broader Neocoleoidea are also ...

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. There are two forms of reproduction: Asexual reproduction, asexual and Sexual ...

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: * Spawning, 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: Armageddon' ...

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 grounds). Commercial fisheries include wild fisheries and fish farm ...

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 *Marketing, the act of sat ...

, 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 and anglers are careful to follow ...

world record for the species stands at 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 fish of West Africa African threadfish Taxa named by Étienne Geoffroy Saint-Hilaire