African lungfish | |
---|---|
Protopterus annectens | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Sarcopterygii |
Class: | Dipnoi |
Order: | Ceratodontiformes |
Family: | Protopteridae Peters, 1855 |
Genus: | Protopterus Owen, 1839 |
Species | |
Synonyms [2] [3] [4] | |
|
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. [5] [6] [7] [8]
The earliest fossils of the Protopteridae come from the Late Cretaceous (Campanian-Maastrichtian) of Sudan, [9] but phylogenetic evidence indicates that it and Lepidosirenidae split at the very beginning of the Early Cretaceous, around 145 Ma. [8] Together, their common ancestor diverged from the only other extant lungfishes in Neoceratodontidae during the Late Jurassic. [10]
Some papers suggest grouping Protopterus and Lepidosiren together in the family Lepidosirenidae, as their Cretaceous divergence is relatively recent compared to the Carboniferous origins of other lungfish families. However, most taxonomic authorities retain them as distinct families. [6] [7] [8]
African lungfish are elongated, eel-like fishes with thread-like pectoral and pelvic fins. They have soft scales, and the dorsal and tail fins are fused into a single structure. They can either swim like eels or crawl along the bottom using their pectoral and pelvic fins. [11] The largest species can reach about 200 cm (6.6 ft) in length. [4]
African lungfish generally inhabit shallow waters, such as swamps and marshes. They are also found in larger lakes such as Lake Victoria. They can survive out of water for many months by burrowing into hardened mud beneath a dried stream bed. They are carnivorous, feeding on crustaceans, aquatic insect larvae, and molluscs. [11]
The African lungfish is an example of how the evolutionary transition from breathing water to breathing air can occur. Lungfish are periodically exposed to water with low oxygen content or encounter situations in which their aquatic environment dries up. To cope with these conditions, they have developed an adaptation in the form of an outpocketing of the gut, similar to the swim bladder found in other fishes. This specialized structure functions as a lung. [11] Within the lung, numerous thin-walled blood vessels allow the blood to absorb oxygen from the air that is gulped into the lung.
They are obligate air breathers, with reduced gills in the adults. There are two anterior gill arches that retain gills, though they are too small to function as the sole respiratory apparatus, and may be more important for carbon dioxide elimination. About 90% of their oxygen is acquired via their lungs, and the remaining ~10% via the gills and skin. [12] The lungfish heart has adaptations that partially separate the flow of blood into its pulmonary and systemic circuits. The atrium is partially divided, so that the left side receives oxygenated blood and the right side receives deoxygenated blood from the other tissues. These two blood streams remain mostly separate as they flow through the ventricle leading to the gill arches. As a result, oxygenated blood mostly goes to the anterior gill arches and the deoxygenated blood mostly goes to the posterior arches.
African lungfishes breed at the beginning of the rainy season. They construct nests or burrows in the mud to hold their eggs, which they then guard against predators. When they hatch, the young resemble tadpoles, with external gills, and only later develop lungs and begin to breathe air. [11]
Until the introduction of the Nile perch to the region, lungfish typically comprised a small proportion of a fisherman's catch. Transportation to market from catching sites in Lake Victoria was often done with fish sun-dried for better preservation. Human consumption of the lungfish varies by population; the Luo peoples occasionally do so but the Sukuma avoid eating lungfish due to a taste which is "locally either highly appreciated or strongly disliked." [13] As technology advancements such as longlines and gillnets have been increasingly applied over the past 50 years, the lungfish populations there are believed to be decreasing.
The family Protopteridae and genus Protopterus contain four extant (living) species: [4]
Other extinct species are known from fossil remains:
A gill is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are kept moist. The microscopic structure of a gill presents a large surface area to the external environment. Branchia is the zoologists' name for gills.
The Anabantidae are a family of ray-finned fish within the order Anabantiformes commonly called the climbing gouramies or climbing perches. The family includes about 34 species. As labyrinth fishes, they possess a labyrinth organ, a structure in the fish's head which allows it to breathe atmospheric oxygen. Fish of this family are commonly seen gulping at air at the surface of the water. The air is held in a structure called the suprabranchial chamber, where oxygen diffuses into the bloodstream via the respiratory epithelium covering the labyrinth organ. This therefore allows the fish to move small distances across land.
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 taxon of the bony fish known as the lobe-finned fish or sarcopterygians, characterised by prominent muscular limb buds (lobes) within the 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 (lepidotrichia) 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 swamp eels are a family (Synbranchidae) of freshwater eel-like fishes of the tropics and subtropics. Most species are able to breathe air and typically live in marshes, ponds and damp places, sometimes burying themselves in the mud if the water source dries up. They have various adaptations to suit this lifestyle; they are long and slender, they lack pectoral and pelvic fins, and their dorsal and anal fins are vestigial, making them limbless vertebrates. They lack scales and a swimbladder, and their gills open on the throat in a slit or pore. Oxygen can be absorbed through the lining of the mouth and pharynx, which is rich in blood vessels and acts as a "lung".
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.
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 and the protist Polychaos dubium at 150 billion and 670 billion, respectively.
Notothenioidei is one of 19 suborders of the order Perciformes. The group is found mainly in Antarctic and Subantarctic waters, with some species ranging north to southern Australia and southern South America. Notothenioids constitute approximately 90% of the fish biomass in the continental shelf waters surrounding Antarctica.
The Gnathorhizidae are an extinct family of lungfish that lived from the late Carboniferous until the middle Triassic. Gnathorhizid fossils have been found in North America, Madagascar, Australia, and possibly Eastern Europe and South Africa. They are characterized by high-ridged toothplates that form cutting blades and a reduction in cranial bones.
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.
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.
Cladistia is a clade of bony fishes whose only living members are the bichirs of tropical Africa. Their major synapomorphies are a heterocercal tail in which the dorsal fin has independent rays, and a posteriorly elongated parasphenoid.
The West African lungfish, also known as the Tana lungfish or simply African lungfish, is a species of African lungfish. It is found in a wide range of freshwater habitats in West and Middle Africa, as well as the northern half of Southern Africa.
Polypterus palmas, also called the shortfin or marbled bichir, is a fish in the family Polypteridae found in freshwater environments throughout West Africa.
Fish gills are organs that allow fish to breathe underwater. Most fish exchange gases like oxygen and carbon dioxide using gills that are protected under gill covers (operculum) on both sides of the pharynx (throat). Gills are tissues that are like short threads, protein structures called filaments. These filaments have many functions including the transfer of ions and water, as well as the exchange of oxygen, carbon dioxide, acids and ammonia. Each filament contains a capillary network that provides a large surface area for exchanging oxygen and carbon dioxide.
There are two major sources of fish in Uganda; one is from aquaculture, the other from fishing in rivers and lakes. Different types of fish flourish in different water sources. The waters of Uganda contain an impressive array of fish species—over 90 in all. This count does not include the Haplochromis complex, which itself is made up of more than 200 species.
Neoceratodontidae is a family of lungfish containing Neoceratodus and the extinct Mioceratodus. It, Lepidosirenidae, and Protopteridae represent the only lungfish families still extant.
Ceratodontiformes is one of two extant orders of lungfish, containing the family Neoceratodontidae as well as many other extinct groups. Members of this group are one of two extant groups of lungfish known to have survived the Permian-Triassic extinction event. Although lungfish originated in marine environments, the Ceratodontiformes have been an exclusively freshwater group since the Carboniferous.