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{{for|the band|Lungfish (band)}}{{automatic taxobox| name = Lungfish! colspan=5| Extant lungfishes! Order! Family! Species! Image! Comments! Ceratodonti-formes! Neocerato-dontidae! rowspan=5 | Lepidosireni-formes! Lepido-sirenidae! rowspan=4 | Proto-pteridae
Early Devonian|Recent}}| image = Queensland Lungfish (Neoceratodus forsteri).jpg| image_caption = Queensland lungfishPer E. Ahlberg>Ahlberg, 1991 | taxon = DipnoiJohannes Peter Müller>J. P. Müller, 1844| subdivision_ranks = Orders| subdivision = }}Lungfish are freshwater rhipidistian fish belonging to the subclass Dipnoi. Lungfish are best known for retaining characteristics primitive within the Osteichthyes, including the ability to breathe air, and structures primitive within Sarcopterygii, including the presence of lobed fins with a well-developed internal skeleton.Today there are only six known species of lungfish, living only in Africa, South America and Australia. The fossil record shows that lungfish were abundant since the Triassic.Agnolin, F. L., Mateus O., Milàn J., Marzola M., Wings O., Adolfssen J. S., & Clemmensen L. B. (2018). Ceratodus tunuensis, sp. nov., a new lungfish (Sarcopterygii, Dipnoi) from the Upper Triassic of central East Greenland. Journal of Vertebrate PaleontologyJournal of Vertebrate Paleontology. e1439834 While vicariance would suggest this represents an ancient distribution limited to the Mesozoic supercontinent Gondwana, the fossil record suggests advanced lungfish had a widespread freshwater distribution and the current distribution of modern lungfish species reflects extinction of many lineages subsequent to the breakup of Pangaea, Gondwana and Laurasia. Lungfish have historically been referred to as salamanderfish,BOOK, The History of Creation, Or, The Development of the Earth and Its Inhabitants by the Action of Natural Causes: A Popular Exposition of the Doctrine of Evolution in General, and of that of Darwin, Goethe, and Lamarck in Particular : from the 8. German Ed. of Ernst Haeckel, Ernst Haeckel, Ernst Heinrich Philipp August Haeckel, Edwin Ray Lankester, L. Dora Schmitz, 1892, D. Appleton, 422,weblink page 289 but this term more often refers to Lepidogalaxias salamandroides.

Anatomy and morphology

All lungfish demonstrate an uninterrupted cartilaginous notochord and an extensively developed palatal dentition. Basal ("primitive") 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 in primitive lungfish are covered in a mineralized tissue called cosmine, but in post-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 to the skull roof bones of ray-finned fishes or tetrapods. During the breeding season, the 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.Piper, Ross (2007), Extraordinary Animals: An Encyclopedia of Curious and Unusual Animals, Greenwood Press.Through convergent evolution, lungfishes have evolved internal nostrils similar to the tetrapods' choana,Evolution: On the evolution of internal nostrils (choanae) and a brain with certain similarities to the lissamphibian 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).The First Virtual Cranial Endocast of a Lungfish (Sarcopterygii: Dipnoi)The dentition of lungfish is different from that of any other vertebrate group. "Odontodes" on the palate and lower jaws develop in a series of rows to form a fan-shaped occlusion surface. These odontodes then wear to form a uniform crushing surface. In several groups, including the modern lepidosireniformes, these ridges have been modified to form occluding blades.The modern lungfishes have a number of larval features, which suggest paedomorphosis. They also demonstrate the largest genome among the vertebrates.Modern lungfish all have an elongate body with fleshy, paired pectoral and pelvic fins and a single unpaired caudal fin replacing the dorsal, caudal and anal fins of most fishes.


missing image!
- Lungs of Protopterus dolloi.JPG -
300 px|Lateral view of lungs of a dissected spotted lungfish (Protopterus dolloi)
Lungfish have a highly specialized respiratory system. They have a distinct feature 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,{{citation|title=Did lungs and the intracardiac shunt evolve to oxygenate the heart in vertebrates|author=Colleen Farmer|journal=Paleobiology|year=1997|url=|deadurl=yes|archiveurl=|archivedate=2010-06-11|df=}} 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.Most extant lungfish species have two lungs, with the exception of the Australian lungfish, which only has one. The lungs of lungfish are homologous to the lungs of tetrapods. As in tetrapods and bichirs, the lungs extend from the ventral surface of the esophagus and gut.Chapter 24: The Respiratory System Evolution Atlas {{webarchive|url= |date=2010-11-25 }}LAB 2 - GNATHOSTOME FORM & FUNCTION

Perfusion of water

Of extant lungfish, only the Australian lungfish can respire through its gills. In other species, the gills are too atrophied to allow for adequate gas exchange. When a lungfish is obtaining oxygen from its gills, its circulatory system is configured similarly to the common fish. The spiral valve of the 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 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 though 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, feeding on fish, insects, crustaceans, worms, mollusks, amphibians and plant matter. They have an intestinal spiral valve rather than a true stomach.JOURNAL, 10.1002/ar.1091820109, 182, Electron microscopy of the intestine of the African lungfish,Protopterus aethiopicus, 1975, The Anatomical Record, 71–89, Purkerson M. L., African and South American lungfish are capable of surviving seasonal drying out of their habitats by burrowing into mud and estivating throughout the dry season. Changes in physiology allow it to slow its metabolism to as little as 1/60th of the normal metabolic rate, and protein waste is converted from ammonia to less-toxic 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.Lungfish can be extremely long-lived. A Queensland lungfish at the Shedd Aquarium in Chicago was part of the permanent live collection from 1933 to 2017, when it was euthanized following a decline in health consistent with old age.WEB,weblink Chicago aquarium euthanizes, 2017-02-06,weblink" title="">weblink 2017-02-07, yes,

Extant lungfish{| class"wikitable"

Queensland lungfish140px)Queensland lungfish, Neoceratodus forsteri, is Endemism>endemic to Australia.LAKE > FIRST = JOHN S. PUBLISHER = MELBOURNE: THOMAS NELSON AUSTRALIA PTY. LTD., 1978 higher vertebrate classes were beginning to evolve.ALLEN TITLE = FIELD GUIDE TO THE FRESHWATER FISHES OF AUSTRALIA. EDS. JAN KNIGHT/WENDY BULGIN PAGES = 54–55, Fossils of lungfish almost identical to this species have been uncovered in northern New South Wales, indicating that the Queensland lungfish has remained virtually unchanged for well over 100 million years, making it a living fossil and one of the oldest living vertebrate genera on the planet. It is the most primitive surviving member of the ancient air-breathing lungfish (Dipnoi) lineages.FRENTIU, F.D., J.R. OVENDEN, AND R. STREET > TITLE = AUSTRALIAN LUNGFISH (NEOCERATODUS FORSTERI: DIPNOI) HAVE LOW GENETIC VARIATION AT ALLOZYME AND MITOCHONDRIAL DNA LOCI: A CONSERVATION ALERT? JOURNAL = CONSERVATION GENETICS DOI = 10.1023/A:1011576116472 VOLUME=2, The five other freshwater lungfish species, Protopterus in Africa and South American lungfish>one in South America, are very different morphologically to N. forsteri. 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.
South American lungfish140px)South American lungfish, Lepidosiren paradoxa, is the single species of lungfish found in swamps and slow-moving waters of the Amazon River>Amazon, Paraguay River, and lower Paraná River drainage basin>basins in South America. Notable as an obligate air-breather, it is the sole member of its family Lepidosirenidae. Relatively little is known about the South American lungfish, or scaly salamander-fish.BOOK, A Naturalist in Brazil: The Record of a Year's Observation of Her Flora, Her Fauna, and Her Peopletranslator=Bernard Miall year=1931, Houghton Mifflin Company, 399, page 275 When immature it is spotted with gold on a black background. In the adult this fades to a brown or gray color.WEB,weblink South American Lungfish, Animal-World, Animal World, Its tooth-bearing premaxillary and maxillary bones are fused like other lungfish. South American lungfishes also share an autostylic jaw suspension (where the palatoquadrate is fused to the cranium) and powerful adductor jaw muscles with the extant lungfish (Dipnoi). Like the African lungfishes, this species has an elongate, almost eel-like body. It may reach a length of {{convert|125|cm|ft}}. The pectoral fins 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."Your Inner Fish" Neil Shubin, 2008,2009,Vintage, p.33 The gills are greatly reduced and essentially non-functional in the adults.BOOK, Paxton, J.R., Eschmeyer, W.N., Bruton, Michael N., 1998, Encyclopedia of Fishes, Academic Press, San Diego, 70, 978-0-12-547665-2,
Marbled lungfish140px)marbled lungfish, Protopterus aethiopicus, is found in Africa. The marbled lungfish is smooth, elongated, and cylindrical with deeply embedded scale (zoology)>scales. The tail is very long and tapers at the end. They can reach a length of up to 200 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) into the adult form, losing the 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.HTTP://ANIMAL-WORLD.COM/ENCYCLO/FRESH/MISC_PSEUDOBONY/LEOPARDLUNGFISH.PHP>TITLE=MARBLED LUNGFISHWORK=ANIMAL WORLD, The marbled lungfish has the largest known genome of any vertebrate, with 133 billion base pairs or building blocks in its DNA double helix. The only organisms known to have more base pairs are protist Polychaos dubium and flowering plant Paris japonica at 670 billion and 150 billion, respectively.IJ LEITCH > DATE = 13 JUNE 2007 JOURNAL = HEREDITY PAGES = 121–122 ISSN = 0018-067X URL = HTTP://WWW.NATURE.COM/HDY/JOURNAL/V99/N2/FULL/6800981A.HTML, 2,
Gilled lungfish140px)gilled lungfish, Protopterus amphibius is a species of lungfish found in East (Retrieved Feb. 19, 2010.) (Retrieved Feb. 19, 2010.) It generally reaches only 44 cm (2 ft.) long, making it the smallest Extant taxon>extant lungfish in the world.Primitive {{webarchiveweblink >date=2008-12-11 }} Retrieved 19 February 2010. This lungfish is uniform blue, or slate grey in colour. It has small or inconspicuous black spots, and a pale grey (Retrieved Sep. 25, 2010.)
West African lungfish140px)| The west African lungfish Protopterus annectens is a species of lungfish found in West (Retrieved May 13, 2010.) (Retrieved May 13, 2010.)WEB,weblink Protopterus annectens, West African lungfish : fisheries, aquaculture, FishBase, It has a prominent snout and small eyes. Its body is long and eel-like, some 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. There are 40-50 scales 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.WEB,weblink West African Lungfish (Protopterus annectens annectens) - Information on West African Lungfish - Encyclopedia of Life, Encyclopedia of Life, They reach a length of about 100 cm in the wild (Retrieved May 13, 2010.) {{webarchive|url= |date=October 11, 2010 }}
Spotted lungfish140px)| The spotted lungfish, Protopterus dolloi, is a species of lungfish found in Africa. Specifically, it is found in the Kouilou-Niari Basin of the Republic of the Congo and Ogowe River basin in Gabon. It is also found in the lower and Middle Congo River Protopterus dolloi can aestivate on land by surrounding itself in a layer of dried mucus.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.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. It can reach a length of up to 130 cm.


File:Ceratodus.jpg|thumb|right|Illustration of Ceratodus by Heinrich HarderHeinrich HarderFile:Ectosteorhachis.JPG|thumb|right|EctosteorhachisEctosteorhachis{{more citations needed|type=animal|auto=yes|date=September 2017}}The relationship of lungfishes to the rest of the bony fish is well understood: Recent molecular genetic analyses strongly support a sister relationship of lungfishes and tetrapods (Rhipidistia), with Coelacanths branching slightly earlier.JOURNAL, The African coelacanth genome provides insights into tetrapod evolution, Nature, 18 April 2013, 10.1038/nature12027,weblink 2013-04-20, 23598338, 496, 7445, 311–316, 3633110, Amemiya, Chris T., Alföldi, Jessica, Lee, Alison P., Fan, Shaohua, Philippe, Hervé, MacCallum, Iain, Braasch, Ingo, Manousaki, Tereza, Schneider, Igor, Rohner, Nicolas, Organ, Chris, Chalopin, Domitille, Smith, Jeramiah J., Robinson, Mark, Dorrington, Rosemary A., Gerdol, Marco, Aken, Bronwen, Biscotti, Maria Assunta, Barucca, Marco, Baurain, Denis, Berlin, Aaron M., Blatch, Gregory L., Buonocore, Francesco, Burmester, Thorsten, Campbell, Michael S., Canapa, Adriana, Cannon, John P., Christoffels, Alan, De Moro, Gianluca, Edkins, Adrienne L., 29, Takezaki, N. and 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}} {{PMID|28082606}} PDF fulltext.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. Additionally, many of the taxa already identified may not be monophyletic.Current phylogenetic studies support the following relationships of major lungfish taxa: Class Osteichthyes, subclass Sarcopterygii, order Dipnoi.{hide}clade| style=font-size:100%;line-height:80%|label1=Dipnoi|1={{clade
|3=Neoceratodus - Queensland lungfish
|1=Lepidosirenidae - South American lungfish

Timeline of genera

ImageSize = width:1000px height:auto barincrement:15pxPlotArea = left:10px bottom:50px top:10px right:10pxPeriod = from:-416 till:-349.2TimeAxis = orientation:horizontalScaleMajor = unit:year increment:5 start:-416ScaleMinor = unit:year increment:1 start:-416TimeAxis = orientation:horAlignBars = justifyColors =
id:CAR  value:claret
id:ANK   value:rgb(0.4,0.3,0.196)
id:HER  value:teal
id:HAD  value:green
id:OMN  value:blue
id:black value:black
id:white value:white
id:paleozoic value:rgb(0.6,0.75,0.55)
id:cambrian value:rgb(0.49,0.63,0.33)
id:ordovician value:rgb(0,0.57,0.44)
id:silurian value:rgb(0.70,0.88,0.71)
id:devonian value:rgb(0.8,0.55,0.22)
id:earlydevonian value:rgb(0.90,0.71,0.43)
id:middledevonian value:rgb(0.96,0.81,0.51)
id:latedevonian value:rgb(0.96,0.89,0.71)
id:carboniferous value:rgb(0.4,0.65,0.6)
id:mississippian value:rgb(0.4,0.56,0.4)
id:pennsylvanian value:rgb(0.8,0.77,0.53)
id:permian value:rgb(0.94,0.25,0.24)
id:mesozoic value:rgb(0.38,0.77,0.79)
id:triassic value:rgb(0.51,0.17,0.57)
id:jurassic value:rgb(0.2,0.7,0.79)
id:cretaceous value:rgb(0.5,0.78,0.31)
id:cenozoic value:rgb(0.95,0.98,0.11)
id:paleogene value:rgb(0.99,0.6,0.32)
id:neogene value:rgb(0.999999,0.9,0.1)
id:quaternary value:rgb(0.98,0.98,0.50)

align:center textcolor:black fontsize:M mark:(line,black) width:25

from: -416 till: -411.2 color:earlydevonian text:Lochkovian
from: -411.2 till: -407 color:earlydevonian text:Pragian
from: -407 till: -397.5 color:earlydevonian text:Emsian
from: -397.5 till: -391.8 color:middledevonian text:Eifelian
from: -391.8 till: -385.3 color:middledevonian text:Givetian
from: -385.3 till: -374.5 color:latedevonian text:Frasnian
from: -374.5 till: -359.2 color:latedevonian text:Famennian

from: -416 till: -359.2 color:devonian text:Devonian
align:left fontsize:M mark:(line,white) width:5 anchor:till align:left

color:earlydevonian bar:NAM1 from:-416 till:-411.2 text:Diabolepis
color:earlydevonian bar:NAM2 from:-416 till:-359.2 text:Devonesteus
color:earlydevonian bar:NAM3 from:-416 till:-359.2 text:Grossipterus
color:earlydevonian bar:NAM4 from:-416 till:-359.2 text:Palaedaphus
color:earlydevonian bar:NAM5 from:-411.2 till:-407 text:Uranolophus
color:earlydevonian bar:NAM6 from:-411.2 till:-359.2 text:Dipterus
color:earlydevonian bar:NAM7 from:-407 till:-403.83 text:Sponysedrion
color:earlydevonian bar:NAM8 from:-407 till:-391.8 text:Dipnorhynchus
color:middledevonian bar:NAM9 from:-397.5 till:-385.3 text:Melanognathus
color:middledevonian bar:NAM10 from:-397.5 till:-385.3 text:Stomiahykus
color:middledevonian bar:NAM11 from:-397.5 till:-359.2 text:Rhinodipterus
color:middledevonian bar:NAM12 from:-391.8 till:-359.2 text:Ganorhynchus
color:middledevonian bar:NAM13 from:-387.5 till:-359.2 text:Conchodus
color:latedevonian bar:NAM14 from:-385.3 till:-381.7 text:Chirodipterus
color:latedevonian bar:NAM15 from:-385.3 till:-381.7 text:Pillararhynchus
color:latedevonian bar:NAM16 from:-385.3 till:-374.5 text:Griphognathus
color:latedevonian bar:NAM17 from:-385.3 till:-374.5 text:Holodipterus
align:center textcolor:black fontsize:M mark:(line,black) width:25

from: -416 till: -411.2 color:earlydevonian text:Lochkovian
from: -411.2 till: -407 color:earlydevonian text:Pragian
from: -407 till: -397.5 color:earlydevonian text:Emsian
from: -397.5 till: -391.8 color:middledevonian text:Eifelian
from: -391.8 till: -385.3 color:middledevonian text:Givetian
from: -385.3 till: -374.5 color:latedevonian text:Frasnian
from: -374.5 till: -359.2 color:latedevonian text:Famennian

from: -416 till: -359.2 color:devonian text:Devonian

See also



Further reading

  • Ahlberg, PE, Smith, MM and Johanson, Z, (2006). Developmental plasticity and disparity in early dipnoan (lungfish) dentitions. Evolution and Development 8(4):331-349.
  • Palmer, Douglas, Ed. The Simon & Schuster Encyclopedia of Dinosaurs & Prehistoric Creatures. A Visual Who's Who of Prehistoric Life. Pg. 45. Great Britain: Marshall Editions Developments Limited. 1999.
  • Schultze, HP, and Chorn, J., (1997). The Permo-Carboniferous genus Sagenodus and the beginning of modern lungfish. Contributions to Zoology 61(7):9-70.
  • JOURNAL, Sepkoski, Jack, A compendium of fossil marine animal genera, Bulletins of American Paleontology, 364, 560, 2002,weblink 2011-05-17, yes,weblink" title="">weblink 2009-02-20,

External links

{{Wikispecies|Dipnoi}} {{Chordata}}{{Sarcopterygii}}{{diversity of fish}}{{Taxonbar|from=Q168422}}

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