Bichirs and the

reedfish The reedfish, ropefish (more commonly used in the United States), or snakefish, ''Erpetoichthys calabaricus'', is a species of fish in the bichir family and order. It is the only member of the genus ''Erpetoichthys''. It is native to fresh and ...

comprise Polypteridae , a

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 ...

of archaic

ray-finned fishes 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 h ...

and the only family in 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 ...

Polypteriformes .Helfman GS, Collette BB, Facey DE, Bowen BW. 2009. The Diversity of Fishes. West Sussex, UK: Blackwell Publishing. 720 p. All the

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 ...

occur in

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

s in 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 ...

and the

Nile The Nile, , Bohairic , lg, Kiira , Nobiin language, Nobiin: Áman Dawū is a major north-flowing river in northeastern Africa. It flows into the Mediterranean Sea. The Nile is the longest river in Africa and has historically been considered ...

River system, mainly swampy, shallow

floodplain A floodplain or flood plain or bottomlands is an area of land adjacent to a river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge.Goudi ...

s and

estuaries 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 ...

. Cladistia, polypterids and their fossil relatives, are considered the

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and t ...

to all other extant ray-finned fishes ( Actinopteri).Dai Suzuki, Matthew C. Brandley, Masayoshi Tokita: ''CORRECTION: The mitochondrial phylogeny of an ancient lineage of ray-finned fishes (Polypteridae) with implications for the evolution of body elongation, pelvic fin loss, and craniofacial morphology in Osteichthyes.'' BMC Evolutionary Biology. Bd. 10, Art.-Nr. 209, 2010, They likely diverged from Actinopteri at least 330 million years ago. A closely related group, the Scanilepiformes, are known from the

Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...

, and are likely ancestral to polypterids. The oldest polypterids are around 100 million years old, from the early

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...

of South America and Africa.

Anatomy

Polypterids are elongated

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 ...

with a unique series of dorsal finlets which vary in number from seven to 18, instead of a single

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 ...

. Each of the dorsal finlets has bifid (double-edged) tips, and are the only fins with spines; the rest of the fins are composed of soft rays. The body is covered in thick, bonelike, and rhombic (

ganoid A fish scale is a small rigid plate that grows out of the skin of a fish. The skin of most jawed fishes is covered with these protective scales, which can also provide effective camouflage through the use of reflection and colouration, as w ...

) scales. Their

jaw The jaw is any opposable articulated structure at the entrance of the mouth, typically used for grasping and manipulating food. The term ''jaws'' is also broadly applied to the whole of the structures constituting the vault of the mouth and serv ...

structure more closely resembles that of the

tetrapod Tetrapods (; ) are four-limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant and extinct amphibians, sauropsids ( reptiles, including dinosaurs and therefore birds) and synapsids (pelycosaurs, extinct theraps ...

s than that of the teleost fishes. Bichirs have a number of other primitive characteristics, including fleshy pectoral fins superficially similar to those of

lobe-finned fishes Sarcopterygii (; ) — sometimes considered synonymous with Crossopterygii () — is a taxon (traditionally a class or subclass) of the bony fishes known as the lobe-finned fishes. The group Tetrapoda, a mostly terrestrial superclass includ ...

. They also have a pair of slit-like

spiracle Spiracle or spiraculum may refer to: * Spiracle (arthropods), opening in the exoskeletons of some arthropods * Spiracle (vertebrates), openings on the surface of some vertebrates * Spiraculum, a genus of land snails in family Cyclophoridae Cycl ...

s on the top of their heads that are used to breathe air, two gular plates, and paired ventral

lung The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of t ...

s (the left lung shorter than the right). Four pairs of gill arches are present. Polypterids have a maximum body length ranging from to over depending on specific species and morphology.

Diet and traits

Polypterids are nocturnal and feed on small vertebrates, crustaceans, and insects. Their common aquarium diet includes bloodworms ( Chironomidae larvae). Polypterids are known to have extraordinary olfactory ability. Polypterid reproduction consists of the female laying anywhere from 100 to 300 eggs over the span of a few days, and subsequent fertilization by the male.

Air breathing

Polypterids possess paired lungs which connect to the esophagus via a

glottis The glottis is the opening between the vocal folds (the rima glottidis). The glottis is crucial in producing vowels and voiced consonants. Etymology From Ancient Greek ''γλωττίς'' (glōttís), derived from ''γλῶττα'' (glôtta), va ...

. They are facultative air-breathers, accessing surface air to breathe when the water they inhabit is poorly oxygenated. Their lungs are highly vascularized to facilitate gas exchange. Deoxygenated arterial blood is brought to the lungs by paired pulmonary arteries, which branch from the fourth efferent branchial arteries (artery from the fourth gill arch), and oxygenated blood leaves the lungs in pulmonary veins. Unlike most lungfish and tetrapods, their lungs are smooth sacs instead of alveolated tissue. Polypterids are unique in that they breathe using recoil aspiration.Graham, J.B. 1997. Air-breathing Fishes: Evolution, diversity, and adaptation. San Diego: Academic Press. 299 p. Polypterids appear to prefer breathing air via their spiracles when undisturbed or in extremely shallow waters where they are unable to incline their body enough to breathe air through their mouth.

Polypterids as aquarium specimens

Polypterids are popular subjects of public and large hobby aquaria. They are sometimes called dragon bichir or dragon fin in pet shops for a more appealing name due to their dragon-like appearance. Though predatory, they are otherwise peaceful, preferring to lie on the bottom (they tend to swim when there are lots of large plants present), and make good tankmates with other species large enough to not be prey but small enough to not eat them. Some aquarists note that pleco catfish eat the slime coat off of polypterids. Polypterids in captivity have life expectancies of 10-30+ years. They greatly appreciate heavily planted tanks as it mimics their natural habitat.

Classification

In addition to the

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus ''Bawitius'', the two living genera, '' Polypterus'' and ''

Erpetoichthys The reedfish, ropefish (more commonly used in the United States), or snakefish, ''Erpetoichthys calabaricus'', is a species of fish in the bichir family and order. It is the only member of the genus ''Erpetoichthys''. It is native to fresh and ...

'', have 12 extant species: Bawitius_restoration

Order Polypteriformes Suborder Polypterioidei Clade Salamandrophysida * Family Polypteridae ** Genus †''

Bawitius ''Bawitius'' is an extinct genus of giant polypterid from the Upper Cretaceous (lower Cenomanian) Bahariya Formation of Egypt. The type species is ''B. bartheli'', named as a species of ''Polypterus'' in 1984, and the genus etymology comes from ...

'' Grandstaff et al. 2012 *** †''

Bawitius bartheli ''Bawitius'' is an extinct genus of giant polypterid from the Upper Cretaceous (lower Cenomanian) Bahariya Formation of Egypt. The type species is ''B. bartheli'', named as a species of ''Polypterus'' in 1984, and the genus etymology comes from ...

'' (Schaal 1984) Grandstaff et al. 2012 - Late Cretaceous (

Cenomanian The Cenomanian is, in the ICS' geological timescale, the oldest or earliest age of the Late Cretaceous Epoch or the lowest stage of the Upper Cretaceous Series. An age is a unit of geochronology; it is a unit of time; the stage is a unit in the s ...

) of Egypt ** Genus †''

Serenoichthys ''Serenoichthys'' is an extinct genus of small bichir from the Late Cretaceous (Cenomanian) of southeastern Morocco. The genus is monotypic, the type and only species being ''Serenoichthys kemkemensis''. Only known at first from postcranial skele ...

'' Dutheil 1999a *** †'' Serenoichthys kemkemensis'' Dutheil 1999a ** Genus ''Erpetoichthys'' J. A. Smith, 1865 *** ''

Erpetoichthys calabaricus The reedfish, ropefish (more commonly used in the United States), or snakefish, ''Erpetoichthys calabaricus'', is a species of fish in the bichir family and order. It is the only member of the genus ''Erpetoichthys''. It is native to fresh and ...

'' J. A. Smith, 1865 (reedfish) ** Genus '' Polypterus''

Lacépède Lacepede can refer to: * Bernard Germain de Lacépède (1756–1825), French naturalist and politician. * Lacepede Bay, a bay in South Australia. * Lacépède, Lot-et-Garonne, a ''commune'' in France * Lacepede Islands, a group of four islands in t ...

, 1803 *** †''

Polypterus dageti ''Polypterus'' is a genus of freshwater fish in the bichir family (Polypteridae) of order Polypteriformes. The type species is the Nile bichir (''P. bichir''). Fish in this genus live in various areas in Africa. ''Polypterus'' is the only kno ...

'' Gayet & Meunier 1996 *** †'' Polypterus faraou'' Otero et al., 2006 — late Miocene *** †''

Polypterus sudanensis ''Polypterus'' is a genus of freshwater fish in the bichir family (Polypteridae) of order Polypteriformes. The type species is the Nile bichir (''P. bichir''). Fish in this genus live in various areas in Africa. ''Polypterus'' is the only kno ...

'' Werner & Gayet 1997 *** Retropinnis group **** ''

Polypterus retropinnis The West African bichir or retropinnis bichir (''Polypterus retropinnis''), is a freshwater fish in the family Polypteridae, is found in the central Congo River basin and Ogooué River in Africa. It is a long, slender fish that grows to a ma ...

'' Vaillant, 1899 (West African bichir) *** Bichir group **** ''

Polypterus ansorgii The Guinean bichir (''Polypterus ansorgii'') is a ray-finned fish from rivers and other freshwater habitats in Western Africa, ranging from Guinea-Bissau to Nigeria. It reaches a maximum length of , is greenish-brown to black in color, and has la ...

Boulenger Boulenger is a surname. Notable people with the surname include: * Benjamin Boulenger (born 1990), French footballer * Edward George Boulenger (1888–1946), British zoologist, director of aquarium at London Zoo * George Albert Boulenger (1858–1 ...

, 1910 (Guinean bichir) **** '' Polypterus bichir''

, 1803 (Nile bichir) ***** ''P. b. bichir'' Lacepède, 1803 ***** ''P. b. lapradei''

Steindachner Franz Steindachner (11 November 1834 in Vienna – 10 December 1919 in Vienna) was an Austrian zoologist, ichthyologist, and herpetologist. He published over 200 papers on fishes and over 50 papers on reptiles and amphibians. Steindachner describ ...

, 1869 ***** ''P. b. ornatus'' Arambourg 1948 **** ''

Polypterus congicus ''Polypterus congicus'', the Congo bichir, is a species of bichir with a maximum recorded size of . The colour also varies from yellowish brown to grey, darker in the top, paler in the ventral area. It has a pattern of around 8 irregular vertical ...

, 1898 (Congo bichir) **** '' Polypterus endlicheri'' Heckel, 1847 (saddled bichir) *** Weeksii group **** '' Polypterus mokelembembe'' Schliewen &

Schäfer Schaefer is an alternative spelling and cognate for the German language, German word Wikt:Schäfer, ''schäfer'', meaning Wikt:shepherd, 'shepherd', which itself descends from the Old High German ''Wikt:scāphare, scāphare''. Variants "Shaefer", " ...

, 2006 (Mokèlé-mbèmbé bichir) **** ''

Polypterus ornatipinnis ''Polypterus ornatipinnis'', the ornate bichir, is a bony fish found in Lake Tanganyika and the Congo River basin in Central and East Africa. Description ''P. ornatipinnis'' has black and yellow patterning on its body, head, and fins, with 9 to ...

, 1902 (ornate bichir) **** ''

Polypterus weeksii ''Polypterus weeksii'', the mottled bichir, is a fish in the family Polypteridae found in the central basin of the Congo River. It grows to about 54 cm in head-to-tail length. Named in honor of John Henry Weeks (1861-1924), Baptist missio ...

, 1898 (mottled bichir) *** Senegalus group **** '' Polypterus delhezi''

, 1899 (barred bichir) **** ''

Polypterus polli ''Polypterus polli'', Poll's bichir, is a species of bichir from the Malebo Pool and the lower and central basins of the Congo River The Congo River ( kg, Nzâdi Kôngo, french: Fleuve Congo, pt, Rio Congo), formerly also known as the Zaire ...

'' J. P. Gosse, 1988 **** ''

Polypterus palmas ''Polypterus palmas'', also called the shortfin or marbled bichir, is a fish in the family Polypteridae found in freshwater environments throughout West Africa. Distribution ''P. palmas'' has a wide range; it can be found in freshwater environm ...

'' Ayres, 1850 (shortfin bichir) ***** ''P. p. buettikoferi''

, 1891 ***** ''P. p. palmas'' Ayres, 1850 **** '' Polypterus senegalus''

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

, 1829 (gray bichir) ***** ''P. s. meridionalis'' Poll, 1941 (most likely a variant of ''P. s. senegalus'') ***** ''P. s. senegalus'' Cuvier, 1829 **** ''

Polypterus teugelsi ''Polypterus teugelsi'' (Teugelsi bichir) is a species of carnivorous, nocturnal bichir (a group of ray-finned fishes) that lives in the Cross River drainage basin in the country of Cameroon. ''P. teugelsi'' was described in 2004 by Ralf Britz ...

'' Britz, 2004 ( Teugelsi bichir)

References

External links

FishBase entry for Polypteridae
{{Authority control Fish of Africa Extant Cretaceous first appearances Taxa named by Charles Lucien Bonaparte