West African lungfish | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Sarcopterygii |
Class: | Dipnoi |
Order: | Ceratodontiformes |
Family: | Protopteridae |
Genus: | Protopterus |
Species: | P. annectens |
Binomial name | |
Protopterus annectens | |
Subspecies | |
Synonyms [4] [5] | |
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The West African lungfish (Protopterus annectens), also known as the Tana lungfish or simply African lungfish, is a species of African lungfish. [6] [7] It is found in a wide range of freshwater habitats in West and Middle Africa, as well as the northern half of Southern Africa. [7] [6]
Protopterus annectens is an ancient fish thought to have existed for over 400 million years. [8] This longevity is due to its physiological adaptations, which allow it to survive periods of drought, making the lungfish resilient in many habitats. P. annectens is known for its eel-like appearance with an anguilliform body. It has pelvic fins that are described as “whip-like" with skeletal elements. [9] It has a prominent snout and small eyes that are known to be partially blind. Although their eyesight is not well-developed, they have sensory structures called lateral lines. [10] These structures allow them to detect water movement. These sensory receptors extend along the snout of the animal, similar to those found in amphibians and other fish. [11]
Its body is about 9–15 times the length of the head. It has two pairs of long, filamentous fins. The pectoral fins have a basal fringe and are about three times the head length, while its pelvic fins are about twice the head length. In general, three external gills are inserted posterior to the gill slits and above the pectoral fins.
It has cycloid scales embedded in the skin. About 40–50 scales occur between the operculum and the anus, and 36–40 around the body before the origin of the dorsal fin. It has 34–37 pairs of ribs. The dorsal side is olive or brown in color and the ventral side is lighter, with great blackish or brownish spots on the body and fins except on its belly. [12] West African lungfish can grow up to 1 meter long (3.3 feet) and weigh up to 4 kilograms (9 pounds). [13]
The West African lungfish also has another subspecies; P. a. brieni, which is found primarily in southern Africa near the Zambezi, Pungwe and Sabi rivers. [14] [15] The West African lungfish is often confused with the South American lungfish (Lepidosiren paradoxa), which shares similar physical traits, such as paired lungs and burrowing behavior. Despite these similarities, they differ in that the South American lungfish is slimmer and has shorter pelvic fins, whereas P. annectens has longer pelvic fins. It is believed that L. paradoxa and P. annectens diverged during the Cretaceous period, as they share a common phylogeny. [16]
The West African lungfish is historically known as a unique species and an early precursor of fish to tetrapods. Due to its monophyletic clade, Dipnoi, it is the sister group to the tetrapods; this is attributed to its distinctive physiology and inferred data from fossil and taxa records. [9]
P. annectens is unique due to its ability to use its pelvic fin as a “foot” to lift its body off substrate. The lungfish has a range of gaits that include both overlapping and non-overlapping fin contacts, allowing it to have movement patterns that resemble walking. [9] However, this doesn't mean it uses its pelvic fins to walk on land entirely; it is exclusively used to lift itself underwater. Although these animals occasionally travel on land, moving from puddle to puddle to stay moisturized, they do not walk on land in the manner of tetrapods.
The west African lungfish also has the ability to breathe atmospheric air by rising to the water's surface and taking a gulp of air, which it must do every half an hour or so to survive. [10] While they do possess lungs, there is minimal oxygen exchange through them; the lungs are primarily used for atmospheric respiration. [9]
The African lungfish has an omnivorous diet, consisting of various fish, earthworms, plants, and even crustaceans. [17] They also have strong jaws designed to crush prey and powerful suction abilities, which enable them to sift through mud and capture prey. [18] The lungfish can also go for up to 3 1/2 years without any food intake whatsoever. During this time period the lung fish enters a dormancy stage called aestivation, which is similar to hibernation but occurs in the summer instead of winter. To begin aestivation It buries itself in the mud about 12-18 inches deep. As the mud dries, It releases a copious amount of mucus, forming a cocoon that eventually hardens and protects them from the environment, preventing dehydration. [18] [19] The fish then has no direct contact with the outside environment; however, a tube of dried mucus goes into the pharynx of the fish and allows the fish to breathe. The lungfish usually relies on protein for energy, so the nitrogenous waste of amino acids is converted to urea, which builds up in the tissues and is only excreted when the lungfish returns to the water. [13] [20]
The West African lungfish is distributed throughout Africa typically, it can be found in freshwater swamps, backwaters, and small rivers in West and South Africa. [8] [15] It has also been reported in African countries such as Senegal, Niger, Gambia, Western Sudan, Côte d’Ivoire, Sierra Leone, Guinea, and many others. [7] Like other African lungfish, the West African lungfish is an obligate air breather and a freshwater-dwelling fish. [15] It is demersal, meaning that it lives primarily buried within riverbeds. Within its habitat, dry seasons are frequent, causing the rivers and floodplains to dry up. During these periods, the West African lungfish can aestivate for up to a year. [15]
The reproductive life of the African lungfish consists of building nests to lay their eggs during the wet season. The eggs, are about 4mm in diameter, are cared for by the males. About a week after being laid, the eggs hatch, and the males continue to care for the larvae for about two months. During this larval development, their gills are absorbed and transformed into fully developed lungs. Once mature, the young develop fused tooth plates to chew their food, a feature uncommon in most fish. [10] [18]
According to the IUCN, the West African lungfish is currently categorized as being of least concern. However, population density, habitat range, and overall population estimates are not entirely known, as more research is needed on this species’ population. [7] Furthermore, the African lungfish is commonly used for food consumption in many African regions. In Ugandan fish markets, African lungfish can frequently be found. According to some studies, Uganda caught between 15,000 and 22,000 tons of lungfish from 1976 to 1985, but this number decreased from 1985 to 1989. In Kenya, around 1,000 to 3,000 tons have been caught over four decades, but catches have decreased since 2005. [21] According to the same study, many locals in Africa claim that the lungfish are sought for their various benefits, such as treating lactation problems in women, alcoholism, enhancing sexual performance in men, and boosting the immune system. [21]
Coelacanths are an ancient group of lobe-finned fish (Sarcopterygii) in the class Actinistia. As sarcopterygians, they are more closely related to lungfish and tetrapods than to ray-finned fish.
Aestivation is a state of animal dormancy, similar to hibernation, although taking place in the summer rather than the winter. Aestivation is characterized by inactivity and a lowered metabolic rate, that is entered in response to high temperatures and arid conditions. It takes place during times of heat and dryness, which are often the summer months.
Lungfish are freshwater vertebrates belonging to the class Dipnoi. Lungfish are best known for retaining ancestral characteristics within the Osteichthyes, including the ability to breathe air, and ancestral structures within Sarcopterygii, including the presence of lobed fins with a well-developed internal skeleton. Lungfish represent the closest living relatives of the tetrapods. The mouths of lungfish typically bear tooth plates, which are used to crush hard shelled organisms.
Sarcopterygii — sometimes considered synonymous with Crossopterygii — is a clade of vertebrate animals which includes a group of bony fish commonly referred to as lobe-finned fish. These vertebrates are characterised by prominent muscular limb buds (lobes) within their fins, which are supported by articulated appendicular skeletons. This is in contrast to the other clade of bony fish, the Actinopterygii, which have only skin-covered bony spines supporting the fins.
Bichirs and the reedfish comprise Polypteridae, a family of archaic ray-finned fishes and the only family in the order Polypteriformes.
The Australian lungfish, also known as the Queensland lungfish, Burnett salmon and barramunda, is the only surviving member of the family Neoceratodontidae. It is one of only six extant lungfish species in the world. Endemic to Australia, the Neoceratodontidae are an ancient family belonging to the class Sarcopterygii, or lobe-finned fishes.
The South American lungfish, also known as the American mud-fish and scaly salamanderfish, is the single species of lungfish found in swamps and slow-moving waters of the Amazon, Paraguay, and lower Paraná River basins in South America. Notable as an obligate air-breather, it is the sole member of its family Lepidosirenidae, although some authors also place Protopterus in the family. In Brazil, it is known by the indigenous language Tupi name piramboia, which means "snake-fish", and synonyms pirarucu-bóia, traíra-bóia, and caramuru.
Protopterus is the genus of four species of lungfish found in Africa. Protopterus is considered the sole genus in the family Protopteridae, which is grouped with Lepidosiren in the order Lepidosireniformes.
The marbled lungfish is a lungfish of the family Protopteridae. Also known as the leopard lungfish, it is found in Eastern and Central Africa, as well as the Nile region. At 133 billion base pairs, it has the largest known genome of any animal and one of the largest of any organism, along with the flowering plant Paris japonica, the fern Tmesipteris oblanceolata and the protist Polychaos dubium at 150 billion, 160 billion and 670 billion, respectively.
Lepidogalaxias salamandroides is a species of small freshwater fish of Western Australia. It is the only member of the family Lepidogalaxiidae and genus Lepidogalaxias. Common names for this fish include salamanderfish and Shannon mudminnow. Although it is not a lungfish, it resembles lungfish in several respects, including its ability to survive dry seasons by burrowing into the sand. It is on the IUCN Red List as Endangered.
Amphibious fish are fish that are able to leave water for extended periods of time. About 11 distantly related genera of fish are considered amphibious. This suggests that many fish genera independently evolved amphibious traits, a process known as convergent evolution. These fish use a range of methods for land movement, such as lateral undulation, tripod-like walking, and jumping. Many of these methods of locomotion incorporate multiple combinations of pectoral-, pelvic-, and tail-fin movement.
Elpistostegalia is a clade containing Panderichthys and all more derived tetrapodomorph taxa. The earliest elpistostegalians, combining fishlike and tetrapod-like characters, such as Tiktaalik, are sometimes called fishapods. Although historically Elpistostegalia was considered an order of prehistoric lobe-finned fishes, it was cladistically redefined to include tetrapods.
Gnathorhiza is an extinct genus of prehistoric lobe-finned fish (lungfish) which lived from the Carboniferous period to the Early Triassic epoch. It is the only known lungfish genus to have crossed the Permo-Triassic boundary. Several species have been described, ranging in size from 5 to 50 centimeters.
Malapterurus beninensis is a species of electric catfish native to the African nations of Angola, Benin, Cameroon, the Democratic Republic of the Congo, the Republic of the Congo, Equatorial Guinea, Gabon, Ghana, Nigeria and Togo. This species grows to a length of 22 cm (9 in) SL. Its habitat is lowland marshes, rivers, and lakes.
The gilled lungfish, also known as the East African lungfish, is a species of African lungfish. It is found in the swamps and flood plains of East Africa, and has been positively identified in Kenya, Somalia and Mozambique. Records from Tanzania require confirmation and may be the result of introductions.
The spotted lungfish or slender lungfish is a species of lungfish from Middle Africa, where found in the Congo, Kouilou-Niari and Ogowe river basins. It is one of four extant species in the genus Protopterus.
The West African bichir or retropinnis bichir, 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 maximum length of about 34 cm (13 in).
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 by muscles.
The evolution of tetrapods began about 400 million years ago in the Devonian Period with the earliest tetrapods evolved from lobe-finned fishes. Tetrapods are categorized as animals in the biological superclass Tetrapoda, which includes all living and extinct amphibians, reptiles, birds, and mammals. While most species today are terrestrial, little evidence supports the idea that any of the earliest tetrapods could move about on land, as their limbs could not have held their midsections off the ground and the known trackways do not indicate they dragged their bellies around. Presumably, the tracks were made by animals walking along the bottoms of shallow bodies of water. The specific aquatic ancestors of the tetrapods, and the process by which land colonization occurred, remain unclear. They are areas of active research and debate among palaeontologists at present.
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