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Polypterus

Polypterus is a genus of primitive ray-finned fishes in the family Polypteridae and order Polypteriformes, comprising 13 valid species of air-breathing bichirs endemic to freshwater habitats across tropical and subtropical Africa.^[1] These ancient fishes, often described as living fossils due to their morphological similarities to Cretaceous-era ancestors from approximately 96 million years ago, exhibit a suite of basal actinopterygian traits including an elongated body covered in rhomboidal ganoid scales, 5 to 18 separate dorsal finlets with anterior spines, paired lobed pectoral fins homologous to tetrapod limbs, and a vascularized swim bladder functioning as a lung for bimodal respiration.^[2]^[3] Native to river basins such as the Nile, Congo, and Niger, as well as associated swamps, floodplains, and lagoons, Polypterus species thrive in warm, slow-moving or stagnant waters with dense vegetation and low dissolved oxygen levels, where their air-breathing capability provides a survival advantage during hypoxic conditions.^[4] Their distribution spans sub-Saharan Africa from Senegal in the west to Ethiopia in the east and southward to Angola, with some species like P. senegalus exhibiting broad ranges across multiple basins while others, such as P. mokelembembe, are restricted to specific locales like the Congo River.^[5]^[1] As opportunistic carnivores, they primarily feed on small fish, insects, crustaceans, and amphibians, foraging nocturnally along the bottom with their sensory barbels and capable of short terrestrial excursions using pectoral fins.^[2]^[4] Reproduction in Polypterus involves external fertilization, with spawning typically occurring in shallow, vegetated areas during wet seasons; some species demonstrate parental care, where males guard adhesive eggs attached to substrate or plants.^[4] Juveniles possess external gills for additional oxygen uptake, which are resorbed as they mature, and the genus displays notable phenotypic plasticity, such as fin and body shape adjustments in response to environmental substrates.^[2] Valued in scientific research for insights into vertebrate evolution—particularly the transition to land and early ray-finned fish diversification—Polypterus also holds popularity in the aquarium trade, though overcollection threatens certain localized populations.^[6]^[7]

Taxonomy and evolution

Classification

Polypterus belongs to the kingdom Animalia, phylum Chordata, class Actinopterygii (ray-finned fishes), order Polypteriformes, family Polypteridae, and genus Polypterus.^[8] Phylogenetically, the genus represents a basal actinopterygian lineage, positioned as the sister group to all other ray-finned fishes, highlighting its primitive characteristics within the class.^[9] Within Polypteridae, Polypterus diverged from the closely related genus Erpetoichthys during the Neogene period, marking a relatively recent split in the family's evolutionary history.^[10] The etymology of Polypterus derives from Greek roots: "poly" (many) and "pteron" (fin or wing), alluding to the series of dorsal finlets that distinguish members of the genus.^[11] The type species, Polypterus bichir, was designated by Lacepède in 1803.^[12]

Species diversity

The genus Polypterus currently comprises 13 valid species, though taxonomic revisions continue to refine this count based on morphological and molecular evidence.^[13]^[14] All species are endemic to freshwater habitats across tropical and subtropical Africa, including rivers, lakes, swamps, and floodplains, with many exhibiting broad distributions while others occupy restricted ranges such as the Congo River basin.^[14]^[5] For instance, Polypterus congicus is confined to the Congo basin, where it inhabits slow-moving waters with dense vegetation. Among the recognized species, Polypterus senegalus, the gray bichir, stands out for its extensive range spanning West African river systems like the Senegal, Gambia, Niger, Volta, and Chad basins, extending eastward to the Nile River and Lake Turkana.^[5] This adaptability contributes to its status as one of the most widespread polypterids. In contrast, Polypterus ornatipinnis, the ornate bichir, is favored in the aquarium trade for its striking black-and-gold marbled patterning and reaches lengths up to 60 cm, originating from central African rivers. Polypterus delhezi, known as the delicate or barred bichir, is a smaller species, typically growing to 32–44 cm, and is native to the middle Congo River basin, where its seven to eight dark vertical bars provide camouflage in vegetated shallows. Similarly, Polypterus endlicherii, the saddle bichir, displays variable saddle-like patterns of dark blotches on a lighter background and can attain 65 cm, distributed across Nile and Congo systems.^[15] Taxonomic debates within Polypterus often stem from historical misclassifications, including the treatment of regional forms as subspecies rather than distinct species, which genetic analyses have since elevated. For example, mitochondrial DNA studies have revealed polyphyly in groups like P. endlicherii and P. palmas, indicating hidden diversity and prompting revisions that increased the recognized species count from earlier estimates.^[16] A comprehensive 2019 revision integrated morphological, meristic, and molecular data to validate the current 13 species, resolving many synonyms and underscoring the role of genetic evidence in clarifying evolutionary relationships.^[14]

Fossil record

The fossil record of Polypteriformes, the order to which Polypterus belongs, dates back to the Late Cretaceous, with the earliest known specimens from the Cenomanian stage (approximately 100–94 million years ago). These include scales and other disarticulated remains from African sites such as the Bahariya Formation in Egypt, representing the onset of polypterid diversification during a period of peak genus richness in the early Late Cretaceous.^[17]^[10] Fossils confidently assigned to the genus Polypterus appear later, with the earliest records from the Middle Eocene (Lutetian to Bartonian stages, approximately 48–38 million years ago) in North African deposits. Notable examples include fragmentary remains of Polypterus sp. from the Dur At-Talah locality in Libya, consisting of scales, vertebrae, and jaw elements that exhibit characteristics typical of modern forms, such as ganoid scale microstructure and dental patterns. A more complete specimen, Polypterus faraou sp. nov., was described from Late Miocene (approximately 11–5 million years ago) sediments at Toros-Menalla in Chad, marking the first well-preserved polypterid skeleton and confirming the genus's persistence in African freshwater systems.^[18] Key fossil sites are predominantly in Africa, including formations in Libya, Egypt, Morocco, and Chad, which demonstrate geographic continuity with the modern distribution of Polypterus species across the continent's riverine and lacustrine habitats. Earlier Cretaceous polypterid fossils from South America suggest a broader historical range, possibly linked to Gondwanan connections, but post-Cretaceous records are confined to Africa, with no evidence of major genus-specific extinction events disrupting this lineage.^[19]^[10] The evolutionary significance of Polypterus lies in its retention of primitive traits within ray-finned fishes (Actinopterygii), such as rhombic ganoid scales, multiple dorsal finlets, and a functional spiracle, which provide insights into the basal architecture of actinopterygians and their adaptations predating the tetrapod transition. These features, preserved in both fossils and extant species, underscore Polypterus's role as a "living fossil" that bridges early vertebrate evolution, highlighting a cryptic history with a substantial gap between molecular divergence estimates (over 300 million years ago) and the oldest fossils.^[20]

Physical description

External features

Polypterus species exhibit an elongated, snake-like body form, with lengths reaching up to 70 cm in standard length for common species such as P. senegalus. The body is subcylindrical anteriorly and laterally compressed posteriorly, covered entirely in thick, rhombic ganoid scales that form a protective, armor-like dermal skeleton.^[21] These scales feature an external layer of enamel-like ganoine, providing robust defense against predators in their native freshwater environments.^[21] The fin system is distinctive, lacking a continuous dorsal or anal fin. Instead, a series of separate dorsal finlets—ranging from 5 to 18 per species, each comprising a leading-edge spine supporting horizontal rays—runs along the back, resembling a row of flags.^[21] Paired pectoral fins emerge from fleshy, lobe-like bases that resemble primitive limbs, enabling enhanced maneuverability and occasional terrestrial support.^[22] Pelvic fins are present in all species, positioned ventrally toward the posterior body, while the caudal fin is rounded and diphycercal, with symmetrical upper and lower lobes.^[21] The head is relatively small and dorsoventrally depressed, with a terminal mouth featuring jaws of equal length or slight protrusion in one (species-dependent). A pair of sensory barbels on the lower jaw aid in detecting prey along the bottom. Eyes are positioned laterally, typically pale with dark pupils, adapted for low-light conditions.^[23] The pectoral fins attach via muscular stalks to the skull-integrated girdle, enhancing their limb-like appearance and function.^[24] Coloration varies by species but generally includes mottled olive-brown to dark brown patterns dorsally and laterally for camouflage among vegetation and substrate, with creamy white undersides. For example, P. senegalus displays grey or beige tones accented by dark spots and blotches, while other species like P. teugelsi feature a network of black markings on an olive background. These patterns provide species-specific visual distinctions, aiding in identification and environmental blending.^[25]

Internal anatomy

The skeletal system of Polypterus features a robust vertebral column composed of numerous vertebrae, with species such as P. bichir possessing 61–62 vertebrae in total. This column extends to support the diphycercal caudal fin and includes unique features like dorsal and ventral ribs attaching to the upper and lower parts of the vertebrae, contributing to structural stability in aquatic environments.^[26] The overall skeleton is well-ossified, reflecting primitive actinopterygian traits.^[27] Additionally, the swim bladder is modified into a lung-like structure, aiding in both buoyancy and respiration.^[27] The respiratory organs of Polypterus include paired lungs derived from the swim bladder, which are connected to the pharynx via a pneumatic duct for air intake.^[28] These lungs are vascularized and function as accessory breathing organs, enabling aerial respiration in low-oxygen conditions.^[29] A prominent spiracle located dorsally on the head serves as the primary entry point for air, facilitating up to 93% of air breaths through aspiration in species like P. senegalus.^[30] The digestive system of Polypterus is characterized by a relatively simple intestine that lacks large supranuclear vacuoles typical of some other fish, instead featuring cilia-bearing enterocytes with apical pinocytotic vesicles for nutrient absorption.^[31] Sensory structures include electroreceptive ampullae of Lorenzini-like organs, with approximately 1,000 such ampullary electroreceptors concentrated on the head, consisting of short canals filled with jelly-like material and innervated by the anterior lateral line nerve.^[32] These organs detect weak electric fields, analogous to those in elasmobranchs.^[32] The reproductive system consists of paired gonads, with ovaries in females and testes in males; Polypterus species are oviparous, with external fertilization.^[33]

Physiology and behavior

Respiration

Polypterus species employ bimodal respiration, extracting oxygen from water primarily through their gills while relying on paired lungs for aerial breathing, an adaptation that enables survival in hypoxic aquatic environments.^[34] In well-oxygenated water, gill-based oxygen uptake accounts for a substantial portion of total respiration, but as dissolved oxygen levels decline, the contribution from air breathing via lungs increases significantly, often exceeding 90% in severe hypoxia.^[35] The air-breathing process involves recoil aspiration, where exhalation occurs via contraction of torso muscles that compress the lungs and deform the rigid, scale-covered body wall, expelling air through the mouth or operculum. Upon relaxation, the elastic recoil restores the body shape, creating negative intrapulmonary pressure (typically -530 to -800 Pa) that draws air into the buccopharyngeal cavity predominantly through the spiracle—a dorsal opening behind the eye—allowing the fish to remain mostly submerged while accessing the surface; the spiracle accounts for up to 93% of inhalations under secure conditions. A subsequent cycle of buccal pumping, involving coordinated movements of the mouth and operculum, transfers the air to the lungs through the glottal valve.^[36]^[34] In captivity under normoxic conditions, Polypterus individuals surface to breathe air periodically, with the frequency adapting dynamically—increasing from baseline rates (about every 20-30 minutes) up to every few minutes in severe hypoxic settings to sustain oxygen homeostasis.^[34] This respiratory strategy underscores the evolutionary significance of Polypterus, as its lung ventilation mechanism mirrors that proposed for early stem tetrapods, providing insights into the water-to-land transition.^[34]

Locomotion and feeding

Polypterus species primarily utilize an undulatory locomotion pattern in water, generating thrust through lateral oscillations of the body and tail, which allows efficient propulsion in their freshwater habitats.^[37] This axial undulation is often combined with movements of the pectoral fins, enabling a form of axial-appendicular locomotion that provides maneuverability near the substrate.^[38] In shallow or drying conditions, these fish employ their pectoral fins to "walk" along the bottom, pushing against the substrate to move forward in a tetrapod-like gait.^[39] As carnivorous predators, Polypterus species adopt an ambush strategy, lying in wait on the river or lake bottom to capture small fish, aquatic invertebrates, and insects that venture close.^[40] Their diet consists mainly of these prey items, with studies showing consumption of small fish and insect larvae in natural environments.^[41] To detect hidden prey in sediment or murky water, they use fleshy maxillary barbels equipped with taste buds for chemoreception and mechanoreception, probing the substrate to sense chemical cues and vibrations.^[42] These fish exhibit nocturnal activity patterns, remaining largely inactive and hidden during the day while foraging actively at night as bottom-dwellers.^[43] This behavior aligns with their ambush tactics in low-light conditions. Additionally, Polypterus can briefly tolerate emersion from water by gulping air into their swim bladder for respiration and using pectoral fin-assisted locomotion to traverse land short distances, aiding survival in fluctuating aquatic environments.^[44] Sensory integration enhances their hunting efficiency, particularly through passive electroreception via ampullary organs distributed across the head and body, which detect weak bioelectric fields from prey in dark, turbid waters where vision is limited.^[45] This electrosensory capability, combined with barbel probing, allows precise prey localization without relying on eyesight.^[46]

Habitat and ecology

Distribution

Polypterus species are endemic to freshwater systems across sub-Saharan Africa, ranging from the Nile River basin in the east, through the Congo River basin in central Africa, to major West African river systems including the Senegal, Gambia, Niger, Volta, and Chad basins; the genus is notably absent from Madagascar and other islands. This distribution reflects the tropical and subtropical freshwater environments of the continent, with no records outside Africa.^[10] These fish primarily inhabit slow-moving or stagnant freshwater habitats such as rivers, swamps, floodplains, and marginal lagoons, where they prefer muddy or vegetated bottoms for cover. The majority are strictly freshwater dwellers.^[47] Species distribution varies widely within the genus; for instance, Polypterus senegalus has a broad range spanning West Africa and extending into the Nile basin, making it one of the most widespread members. In contrast, others are more localized, such as Polypterus bichir, which is primarily restricted to the Nile River and its tributaries including Lake Turkana, and Polypterus teugelsi, endemic to the upper Cross River system in Cameroon.^[47] Movement patterns are generally limited, with Polypterus species showing sedentary behavior in permanent waters but undertaking short seasonal migrations into floodplains during wet periods to exploit expanded habitats and resources. These movements, observed in species like Polypterus senegalus, align with annual flood pulses in river systems. Habitat degradation from deforestation and pollution threatens some localized populations.^[48]^[49]^[50]

Environmental adaptations

Polypterus species exhibit remarkable adaptations to hypoxic aquatic environments, primarily through their ability to breathe atmospheric air via a lung-like swim bladder, enabling survival in stagnant, oxygen-depleted waters common in their tropical habitats. This air-breathing mechanism allows them to supplement gill respiration when dissolved oxygen levels drop, as observed in studies where Polypterus senegalus increases air-breathing frequency in response to low oxygen conditions. Additionally, certain species, such as Polypterus senegalus, can burrow into moist mud for short-term survival during drying periods, relying on air-breathing to endure until water returns; unlike lungfishes, they do not enter prolonged aestivation.^[51]^[52]^[53] These fish thrive in warm temperatures typically ranging from 24–30°C, with tolerance extending to extremes as low as 7°C and up to 31°C, reflecting their broad thermal plasticity suited to fluctuating tropical freshwater systems. Polypterus species maintain optimal physiological function across a pH spectrum of 6–8, accommodating the variable acidity in swamp and floodplain waters. Some coastal Polypteridae species demonstrate euryhaline capabilities, tolerating brackish conditions, which broadens their habitat range in estuarine-like environments.^[54]^[55]^[56] Predation defense in Polypterus is bolstered by their ganoid scales, which form a rigid, interlocking armor that resists penetration and abrasion from attacks by larger predators. Complementing this physical barrier, their predominantly nocturnal habits minimize exposure to diurnal threats, as they remain hidden in vegetation or substrate during daylight and become active foragers at night.^[57]^[23] In ecological interactions, Polypterus functions as an opportunistic predator, primarily consuming macroinvertebrates such as insects, crustaceans, and mollusks, which it captures using suction feeding along the benthic zone. Conversely, it serves as prey for larger piscivorous fish and avian predators, integrating it into the food web of its native wetlands.^[55]

Reproduction and life cycle

Breeding biology

Breeding in Polypterus species is seasonal and closely tied to environmental cues in their native African habitats, particularly the onset of flooding during the rainy season, which prompts adults to migrate to shallow, vegetated swamps for spawning.^[58] This timing, often peaking from June to August or during transitions to the dry season, ensures optimal conditions for egg survival amid rising water levels and increased food availability.^[59] Sexual dimorphism aids mate selection, with males typically exhibiting larger, more muscular anal fins used in courtship.^[58] Courtship behaviors are initiated by the male, who performs displays such as body quivering, lateral head nudges against the female, and brushing her with his cup-like anal fin while staying in close proximity.^[5] These actions, often accompanied by chasing and following the female through the water, escalate until she accepts, leading her to a suitable spawning site amid dense vegetation.^[5] The process may involve surface leaps by one or both fish, signaling readiness and reinforcing pair bonding during the brief ritual, which typically spans a single day.^[60] Spawning entails external fertilization, where the female scatters adhesive eggs in small batches over submerged plants or substrate, with no nest construction.^[5] Clutch sizes range from 100 to 500 eggs per spawning event, though females may produce multiple clutches annually, contributing to total fecundity of several hundred to over 2,000 eggs depending on body size.^[61] The eggs, measuring approximately 0.5 mm in diameter, adhere firmly to surfaces for protection against currents.^[59] Adults provide no parental care post-spawning, leaving the eggs vulnerable to predation.^[62] Hatching occurs after 3-4 days under typical temperatures of 25-28°C, with newly emerged larvae remaining attached to the substrate while absorbing their yolk sacs for initial nourishment.^[62] This brief embryonic phase transitions quickly to free-swimming fry, which must fend for themselves amid the flooded environment.^[62] Captive breeding of Polypterus has proven challenging due to the need to simulate natural flood cycles, such as through temperature drops or water level changes to mimic rainy season cues. The first successful reproduction of P. senegalus in captivity was achieved in 1964 by Arnoult, marking a milestone that highlighted these environmental replication difficulties but paved the way for subsequent farm-based propagation.^[63]

Development

The embryonic stage of Polypterus species, such as P. senegalus, culminates in hatching after 3–5 days of incubation at temperatures around 28°C, yielding larvae approximately 5–7 mm in total length.^[64] These newly hatched embryos initially depend on branchial gills for aquatic respiration, as the primary lung bud emerges post-hatching around 9 days after fertilization, eventually bifurcating into paired lungs by 13 days.^[65] This sequence underscores the transitional respiratory strategy in early ontogeny, bridging gill-dominated breathing with emerging air-breathing capabilities. In the subsequent larval phase, lasting 1–2 weeks, Polypterus larvae exhibit prominent external gills derived from the hyoid arch, which function as the primary respiratory organs during this free-living period and arise via a heterochronic acceleration of arch development.^[66] Scales form rapidly during this stage, initially along the lateral line before extending to the flanks and tail, while the larvae display tadpole-like morphology with adhesive organs for substrate attachment.^[67] Metamorphosis to the juvenile stage occurs by around 1 month post-hatching, marked by the reduction of external gills, expansion of opercular flaps, onset of aerial respiration, and a shift in pigmentation and locomotion.^[68] Juveniles exhibit rapid initial growth, attaining sexual maturity at 1–2 years of age and lengths of 20–30 cm, with growth rates slowing thereafter; maximum sizes vary by species, up to 70 cm in P. senegalus.^[5] In the wild, Polypterus individuals typically live 15–20 years, though captive specimens can exceed 30 years under optimal conditions.^[5] A distinctive ontogenetic trait is the paedomorphic retention of larval features into adulthood, including the series of multiple dorsal finlets, which reflect evolutionary conservation of primitive actinopterygian morphology.^[64]

History and human interaction

Discovery and research

The genus Polypterus was first discovered and formally described in 1802 by French naturalist Étienne Geoffroy Saint-Hilaire during Napoleon's scientific expedition to Egypt, where specimens of Polypterus bichir were collected from the Nile River. This initial encounter highlighted the fish's distinctive features, including its elongated body, multiple dorsal finlets, and paired lungs, which immediately drew attention for their resemblance to more derived vertebrate groups.^[69] Early classifications of Polypterus were marked by debates over its affinities, with some naturalists initially mistaking it for an amphibian due to its limb-like pectoral fins and air-breathing capabilities. By 1907, however, anatomist E.S. Goodrich resolved much of this uncertainty through detailed comparative studies of its skeletal and scale structures, confirming Polypterus as a true fish and one of the most primitive living actinopterygians. Phylogenetic analyses using mitochondrial DNA sequencing in the 1990s further solidified this position, placing Polypterus at the base of the ray-finned fish clade and excluding affinities with lobe-finned fishes or tetrapods.^[70] Key milestones in Polypterus research include the first successful captive breeding of Polypterus senegalus in 1964 by J. Arnoult, which enabled controlled studies of its reproduction and early development for the first time. A significant 2014 investigation into the biomechanics of lung ventilation revealed that Polypterus employs recoil aspiration—wherein elastic recoil of the lung walls aids exhalation—offering direct insights into the respiratory adaptations that may have facilitated the water-to-land transition in stem tetrapods.^[71]^[34] Recent advances, particularly genomic sequencing efforts post-2020, have sequenced the Polypterus genome alongside other basal ray-finned fishes, uncovering genetic signatures of adaptations such as enhanced limb flexibility and sensory development that inform the evolutionary origins of tetrapod-like traits in vertebrates. In 2025, studies including a high-quality diploid genome assembly and analyses of fin regeneration and transcript diversity further advanced understanding of appendage regeneration and gene expression in P. senegalus. These studies underscore Polypterus as a vital model for understanding ancient divergences in fish phylogeny, though gaps persist in integrating fossil records with ongoing behavioral and ecological research.^[6]^[72]^[73]^[74]

Aquarium trade and conservation

Polypterus species are popular in the ornamental fish trade, particularly in regions like Indonesia and Europe, where they are valued for their unique appearance and prehistoric traits. The genus has gained traction among aquarists, with species such as P. senegalus commonly available through domestic markets and limited international exports. Aquaculture production of P. senegalus has expanded using earthen ponds and concrete tanks, supporting the trade while introducing risks of establishment as non-native populations.^[75] Captive breeding successes for P. senegalus and P. ornatipinnis have reduced reliance on wild-caught specimens in some markets, with techniques including hormone induction and controlled spawning environments. These efforts, first documented for P. senegalus in the mid-20th century and refined in commercial settings, promote sustainable sourcing by producing variants like albinos that appeal to hobbyists. However, unregulated breeding in non-native areas has led to wild establishments, highlighting the need for trade regulations to prevent invasive spread.^[75]^[76] Polypterus populations face threats from habitat degradation in African river systems, including fragmentation by dams that alter flow regimes and block migrations, as seen in basins like the Congo and Nile. Pollution from agricultural runoff, mining, and urban waste contributes to eutrophication and toxic accumulation, affecting water quality in floodplains and swamps where these fish thrive. Overfishing, often using small-mesh nets or poisons, targets them occasionally for local food or bait, exacerbating declines in localized areas. Most species are assessed as Least Concern by the IUCN Red List, with the latest assessments as of 2025 confirming stable populations overall, though habitat pressures persist.^[77]^[78] Conservation measures focus on protected areas in the Congo Basin, such as Upemba National Park, where restricted access in core zones safeguards biodiversity hotspots containing species like P. ornatipinnis. Monitoring programs emphasize co-management with local communities to curb illegal fishing and pollution, while the absence of CITES listing reflects low international trade risks but underscores the need for regional oversight. Sustainable aquaculture holds promise for bolstering aquarium supply without wild harvest, potentially easing collection pressures. Knowledge gaps remain, including emerging climate change effects, such as altered flooding patterns in floodplains that could disrupt spawning and habitat availability.^[79]^[80]^[75]^[81]

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Development of dependence on aerial respiration in Polypterus ...
The respiratory behaviour and partitioning of O2 uptake between air and water were investigated in Polypterus genegalus using continuous-flow and two-phase.Missing: mechanism | Show results with:mechanism
[36]
Air Ventilation by Recoil Aspiration in Polypterid Fishes | Science
The discovery that polypterid fishes breathe by recoil aspiration is the first evidence for aspiration breathing in any lower vertebrate.
[37]
Locomotor flexibility of Polypterus senegalus across various aquatic ...
(3) The last category is axial-appendicular-based locomotion, which combines body undulation and pectoral fins to generate thrust. In the present study, we ...
[38]
Locomotor flexibility of Polypterus senegalus across various aquatic ...
... locomotion involving cyclic oscillations of the axial body, paired with near-simultaneous movements of both pectoral fins. Individuals ≤3.5 cm used tail ...<|control11|><|separator|>
[39]
Fin and body neuromuscular coordination changes during walking ...
Summary: Polypterus senegalus use intermittent high-intensity activity of fin and mid-body muscles during walking compared with more constant,
[40]
Aerial and aquatic visual acuity of the grey bichir Polypterus ...
The present study assessed the aerial and aquatic visual abilities of juvenile grey bichir Polypterus senegalus, fish capable of terrestrial locomotion, ...Missing: barbels prey detection
[41]
Preliminary studies on food and feeding habits of Polypterus ...
It leads a sedentary lifestyle, in some cases switching from feeding on fish, aquatic insect larvae, and other hydrobionts to preferentially feeding on adult ...
[42]
Anatomical structure, and expression of CCL4 and CCL13-like ...
This organ is well adapted for chemoreception and mechanoreception. In the complete absence of visual signals, taste buds in the maxillary barbels could ...
[43]
Bichir Care 101: Tank Mates, Diet, Size, Types, Etc. - Aquarium Source
Nov 1, 2025 · The average bichir lifespan is usually 10-15 years in captivity. However, it's not out of the question for them to hit 20 years of age if they ...<|control11|><|separator|>
[44]
New research set to crack the 'walking fish' phenomenon
Aug 22, 2022 · The bichir "Polypterus senegalus". This African fish can breathe air and 'walk' on land using two front fins. Credit: Dr Valentina Di Santo ...
[45]
Insights into Electroreceptor Development and Evolution from ...
Following the discovery of electroreception in weakly electric teleosts, electroreception ... Fine structure of the ampullary organs of the bichir Polypterus ...
[46]
Electroreception in early vertebrates: survey, evidence and new ...
Feb 11, 2018 · In elasmobranchs (sharks and rays), electroreceptors are called ampullae of Lorenzini (Fig. 2). These are jelly-filled canals, c. 1 mm in ...
[47]
Polypterus senegalus, Gray bichir : fisheries - FishBase
Polypterus senegalus Cuvier, 1829 · Classification / Names Common names | Synonyms | Catalog of Fishes(genus, species) | ITIS | CoL | WoRMS | Cloffa · Environment ...
[48]
Fish communities in the eastern, seasonal-floodplain of the Sudd ...
Fish migration into a southeast section of the seasonal floodplain was led by Clarias gariepinus, Polypterus senegalus and several small species which were ...Missing: movements | Show results with:movements
[49]
John Samuel Budgett (1872–1904): In Pursuit of Polypterus
... Polypterus, a fish found in the lakes, river margins, swamps, and floodplains of tropical central and western Africa and the Nile River system. Budgett, the ...
[50]
Air- breathing in fish: Air- breathing organs and control of respiration
Some of the air-breathing fishes, such as Protopterus, Polypterus and Amia have been shown to have NECs in the gills and/or lungs, although the role of these ...
[51]
Respiration of Air by the Primitive Fish Polypterus senegalus
More recently, it has been shown that the spiracles are used to inhale air which is passed to the lungs3. Air is inspired both in conditions of low oxygen ...Missing: duct | Show results with:duct
[52]
Amphibious fishes: evolution and phenotypic plasticity
Aug 1, 2016 · Early rearing in air has been shown to profoundly alter the phenotype of later life stages in Polypterus ... estivation in mud . Physiol ...
[53]
Locomotor Activity of the Intact and Visually Deprived Senegal Bichir ...
Oct 11, 2024 · ... temperatures (7, 16, 25, 28, and 31°C) covering most of the temperature tolerance range of this species are presented. The maximum values of ...
[54]
(PDF) Food and feeding habits of Hepsetus odoe and Polypterus ...
For most species, sucrose has an indifferent taste, but stimulates food intake only in fish, which consume much plant food, or the latter makes up a ...
[55]
Ontogeny and homology of cranial bones associated with lateral ...
Polypteridae (Cladistii: Polypteriformes) is a group of freshwater and brackish water fishes that includes 14 valid species (Eschmeyer et al., 2019; Moritz ...<|control11|><|separator|>
[56]
Threat-protection mechanics of an armored fish - ScienceDirect.com
Here, the mechanical interaction between the ganoid armor of the predatory fish Polypterus ... predators and prey (Vermeij, 1987, Dietl and Kelley, 2002).
[57]
(PDF) Distribution, Morphometrics, Feeding Evaluation and the ...
Oct 10, 2023 · Distribution, Morphometrics, Feeding Evaluation and the Reproductive Capacity of Polypterus .. males and female fishes. (Table 2).
[58]
Polypterus senegalus - BAP - BIOTOPE AQUARIUM Project
Distribution: Africa: widespread from Senegal and Gambia rivers, Niger and Chad basins to Nile River basin; Lake Albert, Lake Turkana; single record from Congo ...
[59]
[PDF] Growth and reproductive parameters of Polypterus senegalus ...
Nov 4, 2016 · Gonadosomatic Index (GSI). Gonadosomatic indices were calculated using the formula: GSI = Gonad weight (g) x 100. Body weight (g).
[60]
Polypterus senegalus senegalus (Senegal Bichir) - Seriously Fish
This species is more widespread than any other bichir and occurs in no less than 26 countries in Africa, incuding Egypt, Cameroon, Ethiopia, Kenya, Mali, Ivory ...
[61]
A breeding first: The Reedfish - Practical Fishkeeping
The male is then very close to the female, almost touching her, and makes jerking sideways movements with his head towards her body. This stimulates the female.
[62]
Staging of The Early Development of Polypterus (Cladistia
The external gills of bichirs represent prominent adaptive structures, and constitute major breathing organs of their free-living embryos and early larvae ( ...
[63]
Molecular developmental mechanism in polypterid fish provides ...
Jul 28, 2016 · These results demonstrate that the primary lung bud begins to develop after hatching. Figure 1. Lung development in Polypterus senegalus.
[64]
Bichir external gills arise via heterochronic shift that accelerates ...
Mar 26, 2019 · This suggests that the prominent external gills of bichir larva (Figure 1A) initially arise from striking accelerated development of the ...
[65]
(PDF) The Embryonic and Larval Development of Polypterus ...
Jun 11, 2025 · It displays larval and adult stages differing in the skeletal and soft tissues' composition. ... Recently hatched larvae swam at speeds up ...Missing: lifespan | Show results with:lifespan
[66]
Bichir external gills arise via heterochronic shift that accelerates ...
Mar 26, 2019 · This major heterochronic shift in the anteroposterior developmental sequence enables early appearance of the external gills that represent key breathing organs.
[67]
Major discoveries on the dermal skeleton of fossil and Recent ...
Dec 21, 2001 · The polypterid fossil record was for a long time reduced to some scarce, disarticulated bones, mainly scales, found in various African deposits ...
[68]
The Complete Mitochondrial DNA Sequence of the Bichir ... - NIH
Phylogenetic analyses suggest the bichir's placement as the most basal living member of the ray-finned fish and rule out its classification as a lobe-finned ...
[69]
Comportement et reproduction en captivité de Polypterus senegalus C
Aug 7, 2025 · The first viable eggs were laid on March 15, 1962, and these fry were raised and themselves laid viable eggs several times in 1963. The methods ...
[70]
(PDF) Culture, trade and establishment of Polypterus senegalus in ...
Jun 25, 2022 · The African grey bichir Polypterus senegalus is a popular ornamental fish in Indonesia. Pet trade with this species is increasing, and aquaculture production ...<|control11|><|separator|>
[71]
Living Fossils - Keeping Polypterus in the Aquarium
Other notable features include a snake-like body with large pectoral fins, which are used for locomotion and give the Polypterus a very distinctive method of ...
[72]
[PDF] THE DIVERSITY OF LIFE IN AFRICAN FRESHWATERS - IUCN Portal
... threats to freshwater biodiversity ... Pollution...................................................................................................
[73]
https://www.biorxiv.org/content/10.1101/2025.03.12.642910v1
[74]
The Upemba National Park (Upper Congo Basin, DR Congo) - MDPI
This species was described from 'Old Calabar' at the mouth of the Calabar and Cross rivers in Nigeria [40] and its reported distribution extends from the Niger ...
[75]
https://www.researchgate.net/publication/361529101_Culture_trade_and_establishment_of_Polypterus_senegalus_in_Indonesia_with_first_record_of_wild_populations
[76]
[PDF] The Diversity of Life in African Freshwaters - IUCN
The views expressed in this publication do not necessarily reflect those of IUCN or other participating organizations. Published by: IUCN, Gland, Switzerland ...