# Lungfish

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This article is about the animal. For the band, see [Lungfish (band)](/source/Lungfish_(band)).

**Lungfish**, also known as **dipnoans**, are freshwater [vertebrates](/source/Vertebrate) belonging to the [class](/source/Class_(biology)) **Dipnoi**.[1] Lungfish are best known for their innovative respiratory system, including the ability to breathe air, and derived structures within [Sarcopterygii](/source/Sarcopterygii), including the presence of lobed fins with a well-developed internal skeleton. Lungfish represent the closest living relatives of the [tetrapods](/source/Tetrapod) (which includes living amphibians, reptiles, birds and mammals). The mouths of lungfish typically bear tooth plates, which are used to [crush hard shelled organisms](/source/Durophagy).

Today there are only six known species of lungfish, living in [Africa](/source/Africa), [South America](/source/South_America), and [Australia](/source/Australia), though they were formerly globally distributed. The fossil record of the group extends into the Early [Devonian](/source/Devonian), over 410 million years ago. The earliest known members of the group were marine, while almost all post-[Carboniferous](/source/Carboniferous) representatives inhabit freshwater environments.[2]

## Etymology

*Dipnoan* is English, *Dipnoi* is Modern Latin and *δίπνοο (dípnoo)* is Modern Greek. Αll these names are derived from Classical [Greek](/source/Greek_language) *δίπνοος (dípnoos)* “with two breathing structures”, from *δι- (di-)* “twice” and *πνοή (pnoḗ)* “breathing, breath”.

## Anatomy and morphology

All lungfish demonstrate an uninterrupted cartilaginous [notochord](/source/Notochord) and an extensively developed [palatal dentition](/source/Palatal_dentition). [Basal](/source/Basal_(phylogenetics)) ("[primitive](/source/Primitive_(phylogenetics))") lungfish groups may retain marginal teeth and an ossified braincase, but derived lungfish groups, including all modern species, show a significant reduction in the marginal bones and a cartilaginous braincase. The bones of the [skull roof](/source/Skull_roof) in primitive lungfish are covered in a [mineralized tissue](/source/Mineralized_tissue) called [cosmine](/source/Cosmine), but in post-[Devonian](/source/Devonian) lungfishes, the skull roof lies beneath the skin and the cosmine covering is lost. All modern lungfish show significant reductions and fusions of the bones of the skull roof, and the specific bones of the skull roof show no [homology](/source/Homology_(biology)) to the skull roof bones of [ray-finned fishes](/source/Ray-finned_fish) or [tetrapods](/source/Tetrapods). During the breeding season, the [South American lungfish](/source/South_American_lungfish) develops a pair of feathery appendages that are actually highly modified pelvic fins. These fins are thought to improve gas exchange around the fish's eggs in its nest.[3]

Through [convergent evolution](/source/Convergent_evolution), lungfishes have evolved internal nostrils similar to the tetrapods' [choana](/source/Choana),[4] and a brain with certain similarities to [Lissamphibian](/source/Lissamphibia) brain (except for the Queensland lungfish, which branched off in its own direction about 277 million years ago and has a brain resembling that of the *[Latimeria](/source/Latimeria)*).[5]

The dentition of lungfish is different from that of any other [vertebrate](/source/Vertebrate) group. "[Odontodes](/source/Odontode)" on the palate and lower jaws develop in a series of rows to form a fan-shaped [occlusion](/source/Occlusion_(dentistry)) surface. These odontodes then wear to form a uniform crushing surface. In several groups, including the modern [lepidosireniformes](/source/Lepidosireniformes), these ridges have been modified to form occluding blades.

The modern lungfishes have a number of larval features, which suggest [paedomorphosis](/source/Paedomorphosis). They also demonstrate the largest [genome](/source/Genome) among the vertebrates.

Modern lungfish all have an elongate body with fleshy, paired [pectoral](/source/Pectoral_fin) and [pelvic](/source/Pelvic_fin) fins and a single unpaired [caudal fin](/source/Caudal_fin) replacing the [dorsal](/source/Dorsal_fin), caudal and [anal](/source/Anal_fin) fins of most fishes.

## Lungs

Lungfish have a highly specialized [respiratory system](/source/Respiratory_system). They have a distinct feature in that their lungs are connected to the larynx and pharynx without a trachea. While other species of fish can breathe air using modified, vascularized [gas bladders](/source/Gas_bladder),[6] these bladders are usually simple sacs, devoid of complex internal structure. In contrast, the lungs of lungfish are subdivided into numerous smaller air sacs, maximizing the surface area available for [gas exchange](/source/Gas_exchange).

Most extant lungfish species have two lungs, with the exception of the Australian lungfish, which has only one. The lungs of lungfish are homologous to the lungs of tetrapods. As in tetrapods and [bichirs](/source/Bichir), the lungs extend from the ventral surface of the [esophagus](/source/Esophagus) and gut.[7][8]

### Perfusion of water

Of extant lungfish, only the [Australian lungfish](/source/Australian_lungfish) can breathe through its gills without needing air from its lung. In other species, the gills are too atrophied to allow for adequate gas exchange. When a lungfish is obtaining [oxygen](/source/Oxygen) from its gills, its circulatory system is configured similarly to the common fish. The spiral valve of the [conus arteriosus](/source/Conus_arteriosus) is open, the bypass arterioles of the third and fourth gill arches (which do not actually have gills) are shut, the second, fifth and sixth gill arch arterioles are open, the [ductus arteriosus](/source/Ductus_arteriosus) branching off the sixth arteriole is open, and the pulmonary arteries are closed. As the water passes through the gills, the lungfish uses a buccal pump. Flow through the mouth and gills is unidirectional. Blood flow through the secondary lamellae is countercurrent to the water, maintaining a more constant concentration gradient.

### Perfusion of air

When breathing air, the spiral valve of the conus arteriosus closes (minimizing the mixing of oxygenated and deoxygenated blood), the third and fourth gill arches open, the second and fifth gill arches close (minimizing the possible loss of the oxygen obtained in the lungs through the gills), the sixth arteriole's ductus arteriosus is closed, and the pulmonary arteries open. Importantly, during air breathing, the sixth gill is still used in respiration; deoxygenated blood loses some of its carbon dioxide as it passes through the gill before reaching the lung. This is because carbon dioxide is more soluble in water. Air flow through the mouth is tidal, and through the lungs it is bidirectional and observes "uniform pool" diffusion of oxygen.

## Ecology and life history

Lungfish are [omnivorous](/source/Omnivorous), feeding on fish, [insects](/source/Insect), [crustaceans](/source/Crustacean), [worms](/source/Worm), [mollusks](/source/Mollusk), [amphibians](/source/Amphibian) and plant matter. They have an [intestinal spiral valve](/source/Intestinal_spiral_valve) rather than a true [stomach](/source/Stomach).[9]

African and South American lungfish are capable of surviving seasonal drying out of their habitats by burrowing into mud and [estivating](/source/Estivating) throughout the dry season. Changes in [physiology](/source/Physiology) allow it to slow its [metabolism](/source/Metabolism) to as little as one sixtieth of the normal metabolic rate, and protein waste is converted from [ammonia](/source/Ammonia) to less-toxic [urea](/source/Urea) (normally, lungfish excrete nitrogenous waste as ammonia directly into the water).

Burrowing is seen in at least one group of fossil lungfish, the [Gnathorhizidae](/source/Gnathorhizidae).

Lungfish can be extremely long-lived. A [Queensland lungfish](/source/Queensland_lungfish) called "Granddad"[10] at the [Shedd Aquarium](/source/Shedd_Aquarium) in [Chicago](/source/Chicago) was part of the permanent live collection from 1933 to 2017 after a previous residence at the [Sydney Aquarium](/source/Sydney_Aquarium);[11] at 109 years old,[12] it was euthanized following a decline in health consistent with old age.[11]

As of 2022, the oldest lungfish, and probably the oldest aquarium fish in the world is "[Methuselah](/source/Methuselah_(lungfish))", an Australian lungfish 4 feet (1.2 m) long and weighing around 40 pounds (18 kg). Methuselah is believed to be female, unlike [its namesake](/source/Methuselah), and is estimated to be over 90 years old.[10]

## Evolution

About 420 million years ago, during the [Devonian](/source/Devonian), the [last common ancestor](/source/Last_common_ancestor) of lungfish and [tetrapods](/source/Tetrapod) split into two separate evolutionary lineages, with the ancestor of the extant [coelacanths](/source/Coelacanth) diverging a little earlier from a [sarcopterygian](/source/Sarcopterygian) progenitor.[13] *[Youngolepis](/source/Youngolepis)* and *[Diabolepis](/source/Diabolepis)*, dating to 419–417 million years ago, during Early Devonian ([Lochkovian](/source/Lochkovian)), are the currently oldest known lungfish, and show that the lungfishes had adapted to a diet including hard-shelled prey ([durophagy](/source/Durophagy)) very early in their evolution.[14] The earliest lungfish were marine. Almost all post-[Carboniferous](/source/Carboniferous) lungfish inhabit or inhabited freshwater environments. There were likely at least two transitions amongst lungfish from marine to freshwater habitats. The last common ancestor of all living lungfish likely lived sometime between the Late [Carboniferous](/source/Carboniferous)[2] and the [Jurassic](/source/Jurassic).[15] Lungfish remained present in the northern [Laurasian](/source/Laurasia) landmasses into the [Cretaceous](/source/Cretaceous) period.[16]

## Extant lungfish

Extant lungfishes Family Genus Species Neoceratodontidae Neoceratodus Queensland lungfish Lepidosirenidae Lepidosiren South American lungfish Protopteridae Protopterus Marbled lungfish Gilled lungfish West African lungfish Spotted lungfish

The [Queensland lungfish](/source/Queensland_lungfish), *Neoceratodus forsteri*, is [endemic](/source/Endemic) to Australia.[17] Fossil records of this group date back 380 million years, around the time when the [higher vertebrate](/source/Higher_vertebrate) classes were beginning to evolve.[18] Fossils of lungfish belonging to the genus *Neoceratodus* have been uncovered in northern [New South Wales](/source/New_South_Wales), indicating that the Queensland lungfish has existed in Australia for at least 100 million years, making it a [living fossil](/source/Living_fossil) and one of the oldest living vertebrate genera on the planet.[18][19] It is the most primitive surviving member of the ancient air-breathing lungfish (Dipnoi) lineages.[18][20] The five other freshwater lungfish species, [four](/source/Protopterus) in Africa and [one](/source/South_American_lungfish) in South America, are very different morphologically to *N. forsteri*.[18] The Queensland lungfish can live for several days out of the water if it is kept moist, but will not survive total water depletion, unlike its African counterparts.[17]

The [South American lungfish](/source/South_American_lungfish), *Lepidosiren paradoxa*, is the single species of lungfish found in [swamps](/source/Swamp) and slow-moving waters of the [Amazon](/source/Amazon_River), [Paraguay](/source/Paraguay_River), and lower [Paraná River](/source/Paran%C3%A1_River) [basins](/source/Drainage_basin) in South America. Notable as an [obligate](/source/Obligate) air-breather, it is the sole member of its family native to the Americas. Relatively little is known about the South American lungfish.[21] When immature it is spotted with gold on a black background. In the adult this fades to a brown or gray color.[22] Its tooth-bearing [premaxillary](/source/Premaxillary) and [maxillary](/source/Maxilla) bones are fused like other lungfish. South American lungfishes also share an autostylic jaw suspension (where the [palatoquadrate](/source/Palatoquadrate) is fused to the [cranium](/source/Cranium)) and powerful adductor jaw muscles with the extant lungfish (Dipnoi). Like the [African lungfishes](/source/African_lungfish), this species has an elongate, almost eel-like body. It may reach a length of 125 centimetres (4 ft 1 in). The [pectoral fins](/source/Pectoral_fin) are thin and threadlike, while the pelvic fins are somewhat larger, and set far back. The fins are connected to the shoulder by a single bone, which is a marked difference from most fish, whose fins usually have at least four bones at their base; and a marked similarity with nearly all land-dwelling vertebrates.[23] They have the lowest aquatic respiration of all extant lungfish species,[24] and their gills are greatly reduced and essentially non-functional in the adults.[25]

The [marbled lungfish](/source/Marbled_lungfish), *Protopterus aethiopicus*, is found in Africa. The marbled lungfish is smooth and elongated with deeply embedded [scales](/source/Scale_(zoology)), and (starting from the head end) is cylindrical for much of its length. The tail is very long and tapers at the end. They are the largest of the African lungfish species as they can reach a length of up to 200 cm.[26] The pectoral and pelvic fins are also very long and thin, almost spaghetti-like. The newly hatched young have branched external gills much like those of newts. After 2 to 3 months the young transform (called [metamorphosis](/source/Metamorphosis)) into the adult form, losing the [external gills](/source/External_gills) for gill openings. These fish have a yellowish gray or pinkish toned ground color with dark slate-gray splotches, creating a marbling or leopard effect over the body and fins. The color pattern is darker along the top and lighter below.[27] The marbled lungfish's [genome](/source/Genome) contains 133 billion [base pairs](/source/Base_pairs), making it the largest known genome of any [vertebrate](/source/Vertebrate). The only [organisms](/source/Organism) known to have more base pairs are the [protist](/source/Protist) *[Polychaos dubium](/source/Polychaos_dubium)* and the flowering plant *[Paris japonica](/source/Paris_japonica)* at 670 billion and 150 billion, respectively.[28]

The [gilled lungfish](/source/Gilled_lungfish), *Protopterus amphibius* is a species of lungfish found in [East Africa](/source/East_Africa).[29][30] It generally reaches only 44 centimetres (17 inches) long, making it the smallest [extant](/source/Extant_taxon) lungfish in the world.[31] This lungfish is uniform blue, or slate grey in colour. It has small or inconspicuous black spots, and a pale grey belly.[32]

The [west African lungfish](/source/West_African_lungfish), *Protopterus annectens*, is a species of lungfish found in West Africa.[33][34][35] It has a prominent [snout](/source/Snout) and small [eyes](/source/Eye). Its body is long and [eel-like](/source/Eel), some 9–15 times the length of the head. It has two pairs of long, filamentous [fins](/source/Fish_fin). The [pectoral fins](/source/Pectoral_fin) have a basal fringe and are about three times the head length, while its [pelvic fins](/source/Pelvic_fin) are about twice the head length. In general, three external [gills](/source/Fish_gill) are inserted [posterior](/source/Posterior_(anatomy)) to the [gill slits](/source/Gill_slit) and above the pectoral fins. It has [cycloid scales](/source/Cycloid_scale) embedded in the skin. There are 40–50 scales between the [operculum](/source/Operculum_(fish)) and the [anus](/source/Anus) and 36–40 around the body before the origin of the [dorsal fin](/source/Dorsal_fin). It has 34–37 pairs of [ribs](/source/Rib). The [dorsal](/source/Dorsum_(anatomy)) side is olive or brown in color and the [ventral](/source/Ventral) side is lighter, with great blackish or brownish spots on the body and fins except on its belly.[36] They reach a length of about 100 cm in the wild.[37]

The [spotted lungfish](/source/Spotted_lungfish), *Protopterus dolloi*, is a species of lungfish found in Africa. Specifically, it is found in the [Kouilou-Niari](/source/Kouilou-Niari_River) Basin of the [Republic of the Congo](/source/Republic_of_the_Congo) and [Ogowe](/source/Ogowe) River basin in [Gabon](/source/Gabon). It is also found in the lower and Middle [Congo River Basins](/source/Congo_River_Basin).[38] *Protopterus dolloi* can [aestivate](/source/Aestivate) on land by surrounding itself in a layer of dried [mucus](/source/Mucus).[39][40] It can reach a length of up to 130 cm.[38]

## Taxonomy

The relationship of lungfishes to the rest of the [bony fish](/source/Bony_fish) is well understood:

- Lungfishes are most closely related to *[Powichthys](/source/Powichthys)*, and then to the [Porolepiformes](/source/Porolepiformes).
- Together, these taxa form the [Dipnomorpha](/source/Dipnomorpha), the sister group to the [Tetrapodomorpha](/source/Tetrapodomorpha).
- Together, these form the [Rhipidistia](/source/Rhipidistia), the sister group to the [coelacanths](/source/Coelacanth).

Recent molecular genetic analyses strongly support a sister relationship of lungfishes and tetrapods ([Rhipidistia](/source/Rhipidistia)), with coelacanths branching slightly earlier.[41][42]

The relationships among lungfishes are significantly more difficult to resolve. While Devonian lungfish had enough bone in the skull to determine relationships, post-Devonian lungfish are represented entirely by skull roofs and teeth, as the rest of the skull is [cartilaginous](/source/Cartilaginous). Additionally, many of the taxa already identified may not be [monophyletic](/source/Monophyletic).

Phylogeny after Kemp, Cavin & Guinot, 2017[2]

Cladogram after Brownstein et al. 2023[15]

## See also

- *[Ceratodus](/source/Ceratodus)*
- *[Lepidogalaxias salamandroides](/source/Lepidogalaxias_salamandroides)*
- *[Polypteridae](/source/Polypteridae)*

## References

1. ["ITIS - Report: Dipnoi"](https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=161039#null). *www.itis.gov*. Retrieved 2023-03-13.

1. Kemp, Anne; Cavin, Lionel; Guinot, Guillaume (2017-04-01). "Evolutionary history of lungfishes with a new phylogeny of post-Devonian genera". *Palaeogeography, Palaeoclimatology, Palaeoecology*. **471**: 209–219. [Bibcode:2017PPP...471..209K](https://ui.adsabs.harvard.edu/abs/2017PPP...471..209K). [doi:10.1016/j.palaeo.2016.12.051](https://doi.org/10.1016/j.palaeo.2016.12.051). [ISSN 0031-0182](https://www.worldcat.org/issn/0031-0182)

1. Piper, Ross (2007). *Extraordinary Animals: An encyclopedia of curious and unusual animals*. [Greenwood Press](/source/Greenwood_Press)

1. ["Evolution: On the evolution of internal nostrils (choanae)"](http://scienceweek.com/2004/sa041224-3.htm). *Science-Week*. [Archived](https://web.archive.org/web/20120320190643/http://scienceweek.com/2004/sa041224-3.htm) 20 March 2012 at the Wayback Machine. Retrieved 23 September 2011.

1. Clement Alice M (2014). "The first virtual cranial endocast of a lungfish (*sarcopterygii*: *dipnoi*)". *PLOS ONE*. **9** (11). [Bibcode:2014PLoSO...9k3898C](https://ui.adsabs.harvard.edu/abs/2014PLoSO...9k3898C). [doi:10.1371/journal.pone.0113898](https://doi.org/10.1371/journal.pone.0113898). [PMC 4245222](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4245222). [PMID 25427173](https://pubmed.ncbi.nlm.nih.gov/25427173). 10.1371. Text was copied from this source, which is available under a [Creative Commons Attribution 4.0 International License](https://creativecommons.org/licenses/by/4.0/).

1. Colleen Farmer (1997), ["Did lungs and the intracardiac shunt evolve to oxygenate the heart in vertebrates"](http://www.biology.utah.edu/farmer/publications%20pdf/1997%20Paleobiology23.pdf), *Paleobiology*. **23** (3): 358–372, [doi:10.1017/s0094837300019734](https://doi.org/10.1017/s0094837300019734). [S2CID 87285937](https://api.semanticscholar.org/CorpusID:87285937), [archived](https://web.archive.org/web/20100611170942/http://www.biology.utah.edu/farmer/publications%20pdf/1997%20Paleobiology23.pdf) 11 June 2010 at the Wayback Machine

1. Wisenden, Brian (2003). ["Chapter 24: The Respiratory System – Evolution Atlas"](http://cwx.prenhall.com/bookbind/pubbooks/martini10/chapter24/custom2/deluxe-content.html). *Human Anatomy*. Pearson Education, Inc. [Archived](https://web.archive.org/web/20101125095303/http://cwx.prenhall.com/bookbind/pubbooks/martini10/chapter24/custom2/deluxe-content.html) 25 November 2010 at the Wayback Machine.

1. Hilber, S.A. (2007). ["Gnathostome form & function"](http://people.biology.ufl.edu/sahilber/VertZooLab2007/Lab2.htm). Vertebrate Zoology Lab. U. Florida. Lab 2. [Archived](https://web.archive.org/web/20110720083608/http://people.biology.ufl.edu/sahilber/VertZooLab2007/Lab2.htm) 20 July 2011 at the Wayback Machine. Retrieved 31 December 2010.

1. Purkerson, M.L. (1975). "Electron microscopy of the intestine of the African lungfish, *Protopterus aethiopicus*". *The Anatomical Record*. **182** (1): 71–89. [doi:10.1002/ar.1091820109](https://doi.org/10.1002/ar.1091820109). [PMID 1155792](https://pubmed.ncbi.nlm.nih.gov/1155792). [S2CID 44787314](https://api.semanticscholar.org/CorpusID:44787314)

1. ["Methuselah: Oldest aquarium fish lives in San Francisco and likes belly rubs"](https://www.theguardian.com/us-news/2022/jan/26/methuselah-oldest-aquarium-fish-lives-san-francisco). *The Guardian*. 26 January 2022.

1. ["Chicago aquarium euthanizes 90 year-old lungfish"](http://www.startribune.com/chicago-aquarium-euthanizes-more-than-90-year-old-lungfish/412918113/). *Star Tribune*. [Archived](https://web.archive.org/web/20170207031540/http://www.startribune.com/chicago-aquarium-euthanizes-more-than-90-year-old-lungfish/412918113/) 7 February 2017 at the Wayback Machine. Retrieved 6 February 2017.

1. CSIRO. ["DNA reveals the true age of Granddad the lungfish"](https://www.csiro.au/en/news/all/articles/2022/june/granddad-lungfish). *www.csiro.au*. Retrieved 2024-11-26.

1. [Australian lungfish has largest genome of any animal sequenced so far - New Scientist](https://www.newscientist.com/article/2265127-australian-lungfish-has-largest-genome-of-any-animal-sequenced-so-far/)

1. Cui, Xindong; Friedman, Matt; Qiao, Tuo; Yu, Yilun; Zhu, Min (2022-05-02). "The rapid evolution of lungfish durophagy". *Nature Communications*. **13** (1): 2390. [doi:10.1038/s41467-022-30091-3](https://doi.org/10.1038/s41467-022-30091-3). [ISSN 2041-1723](https://www.worldcat.org/issn/2041-1723). [PMC 9061808](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9061808). [PMID 35501345](https://pubmed.ncbi.nlm.nih.gov/35501345)

1. Brownstein, Chase Doran; Harrington, Richard C; Near, Thomas J. (July 2023). ["The biogeography of extant lungfishes traces the breakup of Gondwana"](https://onlinelibrary.wiley.com/doi/10.1111/jbi.14609). *Journal of Biogeography*. **50** (7): 1191–1198. [doi:10.1111/jbi.14609](https://doi.org/10.1111/jbi.14609). [ISSN 0305-0270](https://www.worldcat.org/issn/0305-0270)

1. Frederickson, Joseph A. & Cifelli, Richard L. (January 2017). "New Cretaceous lungfishes (Dipnoi, Ceratodontidae) from western North America". *Journal of Paleontology*. **91** (1): 146–161. [doi:10.1017/jpa.2016.131](https://doi.org/10.1017/jpa.2016.131). [ISSN 0022-3360](https://www.worldcat.org/issn/0022-3360). [S2CID 131962612](https://api.semanticscholar.org/CorpusID:131962612)

1. Lake, John S. (1978). *Australian Freshwater Fishes*. Nelson Field Guides. Melbourne: Thomas Nelson Australia Pty. Ltd. p. 12.

1. Allen, G.R.; Midgley, S.H.; Allen, M. (2002). *Field Guide to the Freshwater Fishes of Australia.*. Perth, W.A.: Western Australia Museum. pp. 54–55.

1. Kemp, Anne & Berrell, Rodney (2020-05-03). ["A New Species of Fossil Lungfish (Osteichthyes: Dipnoi) from the Cretaceous of Australia"](https://www.tandfonline.com/doi/full/10.1080/02724634.2020.1822369). *Journal of Vertebrate Paleontology*. **40** (3). [doi:10.1080/02724634.2020.1822369](https://doi.org/10.1080/02724634.2020.1822369). [ISSN 0272-4634](https://www.worldcat.org/issn/0272-4634). [S2CID 225133051](https://api.semanticscholar.org/CorpusID:225133051)

1. Frentiu, F.D.; Ovenden, J.R.; Street, R. (2001). "Australian lungfish (*Neoceratodus forsteri*: Dipnoi) have low genetic variation at allozyme and mitochondrial DNA loci: A conservation alert?". *Conservation Genetics*. **2**: 63–67. 2. [doi:10.1023/A:1011576116472](https://doi.org/10.1023/A:1011576116472). [S2CID 22778872](https://api.semanticscholar.org/CorpusID:22778872)

1. Haeckel, Ernst Heinrich Philipp August; Lankester, Edwin Ray; Schmitz, L. Dora (1892). [*The History of Creation, or, the Development of the Earth and Its Inhabitants by the Action of Natural Causes*](https://archive.org/details/TheHistoryOfCreationOrTheDevelopmentOfTheEarthAndItsInhabitants_126). D. Appleton. pp. 289, 422. A popular exposition of the doctrine of evolution in general, and of that of Darwin, Goethe, and Lamarck in particular. From the 8th German edition by Ernst Haeckel

1. ["South American Lungfish"](http://animal-world.com/encyclo/fresh/Misc_PseudoBony/SouthAmericanLungfish.php). Animal World. [Archived](https://archive.today/20130102013233/http://animal-world.com/encyclo/fresh/Misc_PseudoBony/SouthAmericanLungfish.php) 2 January 2013 at the Wayback Machine.

1. "Your Inner Fish" Neil Shubin, 2008, 2009, Vintage, p.33

1. [The differential cardio-respiratory responses to ambient hypoxia and systemic hypoxaemia in the South American lungfish, Lepidosiren paradoxa](https://pubmed.ncbi.nlm.nih.gov/11691604/)

1. Bruton, Michael N. (1998). *Encyclopedia of Fishes*. Paxton, J.R. & Eschmeyer, W.N. (eds.). San Diego: Academic Press. p. 70. ISBN 978-0-12-547665-2.

1. [Fishbase.org](http://www.fishbase.org/Summary/SpeciesSummary.php?id=8734)

1. Animal-World. ["Marbled Lungfish"](http://animal-world.com/encyclo/fresh/Misc_PseudoBony/LeopardLungfish.php). *Animal World*. [Archived](https://web.archive.org/web/20070614211811/http://animal-world.com/encyclo/fresh/Misc_PseudoBony/LeopardLungfish.php) 14 June 2007 at the Wayback Machine.

1. IJ Leitch (13 June 2007). "Genome sizes through the ages". *Heredity*. **99** (2): 121–122. Nature Publishing Group. [doi:10.1038/sj.hdy.6800981](https://doi.org/10.1038/sj.hdy.6800981). [ISSN 0018-067X](https://www.worldcat.org/issn/0018-067X). [PMID 17565357](https://pubmed.ncbi.nlm.nih.gov/17565357). [S2CID 5406138](https://api.semanticscholar.org/CorpusID:5406138)

1. [EOL.org](http://www.eol.org/pages/217169) (Retrieved 19 February 2010.)

1. [Fishbase.org](http://www.fishbase.org/summary/Speciessummary.php?id=8735) (Retrieved 19 February 2010.)

1. [Primitive Fishes.com](http://www.primitivefishes.com/Gilled%20African%20Lungfish.htm) [Archived](https://web.archive.org/web/20081211022858/http://www.primitivefishes.com/Gilled%20African%20Lungfish.htm) 11 December 2008 at the Wayback Machine Retrieved 19 February 2010.

1. [Fishbase.org](http://www.fishbase.org/summary/Speciessummary.php?id=8735) (Retrieved 25 September 2010.)

1. [EOL.org](http://www.eol.org/pages/217169) (Retrieved 13 May 2010.)

1. [Fishbase.org](http://www.fishbase.org/summary/Speciessummary.php?id=8735) (Retrieved 13 May 2010.)

1. ["Protopterus annectens, West African lungfish: fisheries, aquaculture"](http://fishbase.org/Summary/SpeciesSummary.php?id=2384). *FishBase*

1. ["West African Lungfish (Protopterus annectens annectens) - Information on West African Lungfish - Encyclopedia of Life"](http://www.eol.org/pages/1298995?text_id=6652736). *Encyclopedia of Life*[dead link]

1. [Primitivefishes.com (Retrieved May 13, 2010.)](http://www.primitivefishes.com/pannectens.htm) [Archived](https://web.archive.org/web/20101011104325/http://www.primitivefishes.com/pannectens.htm) 11 October 2010 at the Wayback Machine

1. [Fishbase.org](http://www.fishbase.org/summary/speciessummary.php?id=8736)

1. Brien, P. (1959). Ethologie du Protopterus dolloi(Boulenger) et de ses larves. Signification des sacs pulmonaires des Dipneustes. Ann. Soc. R. Zool. Belg. 89, 9–48.

1. Poll, M. (1961). Révision systématique et raciation géographique des Protopteridae de l'Afrique centrale. Ann. Mus. R. Afr. Centr. Sér. 8. Sci. Zool. 103, 3–50.

1. Amemiya, Chris T.; Alföldi, Jessica; Lee, Alison P.; Fan, Shaohua; Philippe, Hervé; MacCallum, Iain et al. (18 April 2013). "The African coelacanth genome provides insights into tetrapod evolution". *Nature*. **496** (7445): 311–316. [Bibcode:2013Natur.496..311A](https://ui.adsabs.harvard.edu/abs/2013Natur.496..311A). [doi:10.1038/nature12027](https://doi.org/10.1038/nature12027). [PMC 3633110](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3633110). [PMID 23598338](https://pubmed.ncbi.nlm.nih.gov/23598338)

1. Takezaki, N. & Nishihara, H. (2017). "Support for lungfish as the closest relative of tetrapods by using slowly evolving ray-finned fish as the outgroup". *Genome Biology and Evolution*. **9** (1): 93–101. [doi:10.1093/gbe/evw288](https://doi.org/10.1093/gbe/evw288). [PMC 5381532](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5381532). [PMID 28082606](https://pubmed.ncbi.nlm.nih.gov/28082606)

## Further reading

- Ahlberg, P.E.; Smith, M.M.; Johanson, Z. (2006). "Developmental plasticity and disparity in early *dipnoan* (lungfish) dentitions". *Evolution and Development*. **8** (4): 331–349. [doi:10.1111/j.1525-142x.2006.00106.x](https://doi.org/10.1111/j.1525-142x.2006.00106.x). [PMID 16805898](https://pubmed.ncbi.nlm.nih.gov/16805898). [S2CID 28339324](https://api.semanticscholar.org/CorpusID:28339324)
- Palmer, Douglas (ed.) (1999). *The Simon & Schuster Encyclopedia of Dinosaurs & Prehistoric Creatures, A visual who's who of prehistoric life.*. Great Britain: Marshall Editions Developments Limited. p. 45.
- Schultze, H.P. & Chorn, J. (1997). "The Permo-Carboniferous genus *Sagenodus* and the beginning of modern lungfish". *Contributions to Zoology*. **61** (7): 9–70. [doi:10.1163/18759866-06701002](https://doi.org/10.1163/18759866-06701002)
- Sepkoski, Jack (2002). ["A compendium of fossil marine animal genera"](http://strata.ummp.lsa.umich.edu/jack/showgenera.php?taxon=611&rank=class). *Bulletins of American Paleontology*. **364**: 560. [Archived](https://web.archive.org/web/20090220223520/http://strata.ummp.lsa.umich.edu/jack/showgenera.php?taxon=611&rank=class) 20 February 2009 at the Wayback Machine. Retrieved 17 May 2011.

## External links

- Kemps, Anne, Dr. ["Lungfish Information site"](http://annekempslungfish.com/index.html). [Archived](https://web.archive.org/web/20140802224356/http://annekempslungfish.com/index.html) 2014-08-02 at the Wayback Machine.
- ["Dipnoiformes"](http://www.palaeos.com/Vertebrates/Units/140Sarcopterygii/140.500.html). *Palaeos.com*. [Archived](https://web.archive.org/web/20060313152753/http://www.palaeos.com/Vertebrates/Units/140Sarcopterygii/140.500.html) 2006-03-13 at the Wayback Machine.
- ["Dipnoi"](http://www.ucmp.berkeley.edu/vertebrates/sarco/dipnoi.html). University of California Museum of Paleontology.
- ["Tree of life illustration showing lungfish's relation to other organisms"](http://www.tellapallet.com/tree_of_life.htm). *tellapallet.com*. [Archived](https://web.archive.org/web/20090123062500/https://www.tellapallet.com/tree_of_life.htm) 2009-01-23 at the Wayback Machine.
- ["Lungfish video"](https://www.youtube.com/watch?v=D1UKHimLZao). *YouTube*. [Archived](https://ghostarchive.org/varchive/youtube/20211118/D1UKHimLZao) 2021-11-18 at the Wayback Machine.

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Adapted from the Wikipedia article [Lungfish](https://en.wikipedia.org/wiki/Lungfish) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Lungfish?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.