List of semiaquatic tetrapods

This is a list of tetrapods that are semiaquatic; that is, while being at least partly terrestrial, they spend part of their life cycle or a significant fraction of their time in water as part of their normal behavior, and/or obtain a significant fraction of their food from an aquatic habitat. The very earliest tetrapods, such as Ichthyostega, were semiaquatic, having evolved from amphibious lobe-finned fish.

Restoration of Ichthyostega, an early tetrapod from the Devonian
Marine otter of the west coast of South America
Hawaiian monk seal, off Kaʻula Island

Some marine mammals, such as the marine otter, the polar bear and pinnipeds, are semiaquatic, while others, such as the sea otter, cetaceans and sirenians, are fully aquatic. The only fully aquatic nonmarine mammals are several manatees (the Amazonian manatee and some populations of African manatee) and certain small cetaceans (river dolphins, the tucuxi, and some populations of Irrawaddy dolphin and finless porpoise). No bird species is fully aquatic, as all must lay and incubate their amniotic eggs, as well as begin raising their young, on land or ice. Similarly among marine reptiles, sea turtles are almost fully aquatic, but must come ashore to lay eggs. Marine iguanas and partly marine crocodiles (such as the saltwater crocodile and the American crocodile) are all semiaquatic. Most sea snakes are ovoviviparous (live-bearing) and fully aquatic (the exceptions being the oviparous, semiaquatic sea kraits). A few freshwater snakes are also ovoviviparous and fully aquatic (e.g., Erpeton tentaculatum and Acrochordidae), but the majority are semiaquatic. Most amphibians have an aquatic larval stage and are at least semiaquatic for that reason, but there are many exceptions to this generalization.

The aquatic component of a semiaquatic species' lifestyle may be either obligatory or facultative to varying degrees (examples of the latter are the Arctic fox, jaguar and green iguana).

Note: dagger symbols, "†", have been used to indicate a listed taxon is extinct.


All extant fully aquatic mammals except the sea otter are found in two clades of exclusively aquatic species, Cetacea and Sirenia; the extinct desmostylians are also thought to have been fully aquatic (these groups are thought to have become fully aquatic about 45, 40 and 30 Ma ago, respectively). In contrast, semiaquatic mammals are widely distributed throughout the class. However, extant semiaquatic swimming marine mammals are restricted to Carnivora (among which, pinnipeds apparently appeared about 20 Ma ago). Semiaquatic (carnivorous) rodents have been noted as having larger than normal brains for their size, possibly as a consequence of using their vibrissae for acoustic detection of prey.[1][2]

Platypus, a semiaquatic monotreme, Tasmania
Asian elephant using its trunk as a snorkel,[3] India
Invasive coypu, Europe
Muskrat, Ontario
Male waterbuck, Kenya
Female moose, Wyoming
Hippopotamus underwater
Emperor penguins, Antarctica
Brown pelican, Florida
Male wood duck, Quebec


The great majority of semiaquatic birds are found within three clades whose members are mostly semiaquatic: Aequorlitornithes, Anseriformes and Gruiformes, thought to be about 64, 47 and 41 Ma old, respectively.[27][note 2]

Nonavian dinosaursEdit

Hesperornis restoration
Spinosaurus restoration

Only a few nonavian dinosaurs are thought to have been semiaquatic. While the Mesozoic had many types of marine reptiles, the combination of being oviparous and endothermic seems to have prevented the evolution of fully aquatic dinosaurs, as in birds.


Eudimorphodon restoration
Pterodaustro restoration, showing its bristle-like modified teeth, likely used for filter feeding as in flamingos

A number of types of pterosaurs are thought to have been piscivores, and a few are suspected of being molluscivores.

Other reptilesEdit

Nile crocodile swimming sequence
Marine iguana, Galápagos Islands
Blue-lipped sea krait, Java; note paddle-like tail

Semiaquatic forms are widely distributed among extant and extinct reptiles, and extinct semiaquatic or fully aquatic marine forms were once ecologically prominent.

North American eastern newt as a gilled aquatic larva, aposematic terrestrial juvenile ("red eft") and aquatic adult


Amphibians differ from other semiaquatic tetrapods in that their semiaquatic lifestyle is ancestral, rather than being the result of a secondary evolutionary trend from a terrestrial state back towards an aquatic environment. Thus, they are the only tetrapods to possess gills. All extant amphibians that are semiaquatic or fully aquatic inhabit freshwater habitats, with the exception of the crab-eating frog, which also exploits brackish habitats.

Most amphibians have an aquatic larval stage and thus are at least semiaquatic by virtue of this fact. Many adult amphibians are also semiaquatic (while others are fully aquatic or terrestrial). However, some amphibians lack an aquatic larval stage. Some frogs, such as most leiopelmatids, most ranixalids, some leptodactylids, some myobatrachids, Darwin's frog and the Seychelles frog, have nonaquatic tadpoles. Some caecilians, many frogs such as saddleback toads, most sooglossids and the greenhouse frog,[32] and most plethodontid salamanders lay eggs on land in which the larvae develop into adult form before they hatch. The alpine salamander[33] and African live-bearing toads (Nectophrynoides and Nimbaphrynoides)[34] are ovoviviparous and give birth on land. Additionally, about 75% of caecilians are viviparous.

See alsoEdit


  1. ^ Elephants have a system of cracks in their skin which retains water and mud for purposes of thermoregulation and protection from insect parasites and UV radiation. This system is less developed in Asian elephants than in African bush elephants; the former generally live in more mesic habitats.[5]
  2. ^ These dates are without calibration based on the putative late Cretaceous fossil crown avian Vegavis; its inclusion would push back the date for Anseriformes to ~69 Ma.
  3. ^ Although all extant crocodilians are semiaquatic, some recently extinct mekosuchine genera, Mekosuchus and Quinkana, were mostly or entirely terrestrial.


  1. ^ Voss, R. S. (1988). "Systematics and ecology of ichthyomyine rodents (Muroidea) : patterns of morphological evolution in a small adaptive radiation". Bulletin of the American Museum of Natural History. 188: 259–493 (see p. 410). hdl:2246/927.
  2. ^ Peterhans, J. C. K.; Patterson, B. D. (1995). "The Ethiopian water mouse Nilopegamys Osgood, with comments on semi-aquatic adaptations in African Muridae". Zoological Journal of the Linnean Society. 113 (3): 329–349 (see pp. 341–346). doi:10.1111/j.1096-3642.1995.tb00937.x.
  3. ^ a b West, J.B. (April 2002). "Why doesn't the elephant have a pleural space?". News in Physiological Sciences. 17 (2): 47–50. doi:10.1152/nips.01374.2001. PMID 11909991. S2CID 27321751.
  4. ^ Domning, D. P. (2001-10-11). "The earliest known fully quadrupedal sirenians". Nature. Nature Publishing Group. 413 (6856): 625–627. Bibcode:2001Natur.413..625D. doi:10.1038/35098072. PMID 11675784. S2CID 22005691.
  5. ^ Lillywhite, H. B.; Stein, B. R. (1987). "Surface sculpturing and water retention of elephant skin". Journal of Zoology. 211 (4): 727–734. doi:10.1111/j.1469-7998.1987.tb04483.x.
  6. ^ Johnson, D. L. (1980). "Problems in the Land Vertebrate Zoogeography of Certain Islands and the Swimming Powers of Elephants". Journal of Biogeography. 7 (4): 383-398 (see pp. 385-386). doi:10.2307/2844657. JSTOR 2844657.
  7. ^ West, J.B.; Fu, Z.; Gaeth, A.P.; Short, R.V. (November 2003). "Fetal lung development in the elephant reflects the adaptations required for snorkeling in adult life". Respiratory Physiology & Neurobiology. 138 (2–3): 325–333. doi:10.1016/S1569-9048(03)00199-X. PMID 14609520. S2CID 24902376.
  8. ^ Isabella, J. (21 April 2020). "The Wonderful, Transcendent Life of an Odd-Nosed Monkey". Hakai Institute. Retrieved 2020-05-03.
  9. ^ Nedelman, M. (2018-04-19). "Diving deep on one breath could be in a 'sea nomad's' DNA". CNN. Retrieved 2018-04-20.
  10. ^ Zimmer, Carl (2018-04-19). "Bodies Remodeled for a Life at Sea". The New York Times. ISSN 0362-4331. Retrieved 2018-04-23.
  11. ^ Ilardo, M. A.; Moltke, I.; Korneliussen, T. S.; Cheng, J.; Stern, A. J.; Racimo, F.; de Barros Damgaard, P.; Sikora, M.; Seguin-Orlando, A.; Rasmussen, S.; van den Munckhof, I. C. L.; ter Horst, R.; Joosten, L. A. B.; Netea, M. G.; Salingkat, S.; Nielsen, R.; Willerslev, E. (2018-04-18). "Physiological and Genetic Adaptations to Diving in Sea Nomads". Cell. 173 (3): 569–580.e15. doi:10.1016/j.cell.2018.03.054. PMID 29677510.
  12. ^ a b Walker, M. (2009-07-07). "Aquatic deer and ancient whales". BBC News. Retrieved 2010-03-26.
  13. ^ Stadelmann, B.; Herrera, L. G.; Arroyo-Cabrales, J.; Flores-Martínez, J. J.; May, B. P.; Ruedi, M.; Miller, E. H. (2004). "Molecular Systematics of the Fishing Bat Myotis (Pizonyx) vivesi". Journal of Mammalogy. 85 (1): 133–139. doi:10.1644/1545-1542(2004)085<0133:MSOTFB>2.0.CO;2.
  14. ^ Geffen, E.; Waidyaratne, S.; Dalén, L.; Angerbjörn, A.; Vila, C.; Hersteinsson, P.; Fuglei, E.; White, P.A.; Goltsman, M.; Kapel, C.M.O.; Wayne, R.K. (2007). "Sea ice occurrence predicts genetic isolation in the Arctic fox". Molecular Ecology. 16 (20): 4241–4255. doi:10.1111/j.1365-294X.2007.03507.x. PMID 17868292. S2CID 23691015.
  15. ^ Roth, J. D. (2003). "Variability in marine resources affects arctic fox population dynamics". Journal of Animal Ecology. 72 (4): 668–676. doi:10.1046/j.1365-2656.2003.00739.x. PMID 30893960. (see p. 673)
  16. ^ "Arctic Fox Facts". Churchill Wildlife Guide. Natural Habitat Adventures & World Wildlife Fund. 2019. Retrieved 2019-12-15.
  17. ^ Brears, R.C. (2017). "Arctic Foxes: Constant Gardeners of the Arctic". Oceanwide Expeditions. Retrieved 2019-12-15.
  18. ^ de Mello Beiseigel, B.; Zuercher, G.L. (2005). "Speotheos venaticus". Mammalian Species. 783: 1–6. doi:10.1644/783.1. S2CID 198129207.
  19. ^ Fox, M. W. (1984). The Whistling Hunters: Field Studies of the Asiatic Wild Dog (Cuon Alpinus). Albany: State University of New York Press. p. 67. ISBN 978-0-9524390-6-6.
  20. ^ "Panthera onca, Jaguar". North American Mammals. Smithsonian Natural History Museum. Retrieved 2018-01-30.
  21. ^ Seymour, K. L. (26 October 1989). "Panthera onca" (PDF). Mammalian Species. 340 (340): 1–9. doi:10.2307/3504096. JSTOR 3504096. Archived from the original (PDF) on 2011-12-20.
  22. ^ Burton, R.F. (26 February 1998). Biology by Numbers: An Encouragement to Quantitative Thinking. Cambridge University Press. ISBN 978-0521576987. OCLC 1141931965. see pp. 84-85.
  23. ^ Jiang, Z.; Harris, R.B. (2016). "Elaphurus davidianus". IUCN Red List of Threatened Species. 2016. Retrieved 29 March 2020.
  24. ^ "Pѐre David's Deer". White Oak. Retrieved 2020-03-29.
  25. ^ Meijaard, E.; Umilaela; de Silva Wijeyeratne, G. (September 2010). "Aquatic escape behaviour in mouse-deer provides insight into tragulid evolution". Mammalian Biology. 75 (5): 471–473. doi:10.1016/j.mambio.2009.05.007.
  26. ^ Lambert, O.; Bianucci, G.; Salas-Gismondi, R.; Di Celma, C.; Steurbaut, E.; Urbina, M.; de Muizon, C. (2019). "An Amphibious Whale from the Middle Eocene of Peru Reveals Early South Pacific Dispersal of Quadrupedal Cetaceans". Current Biology. 29 (8): 1352–1359.e3. doi:10.1016/j.cub.2019.02.050. PMID 30955933.
  27. ^ a b Prum, R. O.; et al. (22 October 2015). "A comprehensive phylogeny of birds (Aves) using targeted next-generation DNA sequencing". Nature. 526 (7574): 569–573. Bibcode:2015Natur.526..569P. doi:10.1038/nature15697. PMID 26444237. S2CID 205246158.
  28. ^ Ibrahim, N.; Sereno, P.C.; Dal Sasso, C.; Maganuco, S.; Fabbri, M.; Martill, D.M.; Zouhri, S.; Myhrvold, N.; Iurino, D.A. (2014). "Semiaquatic adaptations in a giant predatory dinosaur". Science. 345 (6204): 1613–1616. doi:10.1126/science.1258750. PMID 25213375. S2CID 34421257.
  29. ^ Ibrahim, N.; Maganuco, S.; Dal Sasso, C.; Fabbri, M.; Auditore, M.; Bindellini, G.; Martill, D.M.; Zouhri, S.; Mattarelli, D.A.; Unwin, D.M.; Wiemann, J.; Bonadonna, D.; Amane, A.; Jakubczak, J.; Joger, U.; Lauder, G.V.; Pierce, S.E. (2020). "Tail-propelled aquatic locomotion in a theropod dinosaur". Nature. 581 (7806): 67–70. doi:10.1038/s41586-020-2190-3. PMID 32376955. S2CID 216650535.
  30. ^ Swanson, Paul L. (1950), "The iguana: Iguana iguana iguana (L)", Herpetologica, 6 (7): 187–193, JSTOR 3890004
  31. ^ Coles, William (2002), "Green Iguana" (PDF), U.S.V.I. Animal Fact Sheet #08, Department of Planning and Natural Resources US Virgin Islands Division of Fish and Wildlife, archived from the original (PDF) on 2007-12-11
  32. ^ "Eleutherodactylus planirostris". AmphibiaWeb. 2012. Retrieved 2016-04-09.
  33. ^ Chisholm, Hugh, ed. (1911). "Salamander" . Encyclopædia Britannica. 1 (11th ed.). Cambridge University Press.
  34. ^ Channing, A.; Howell, K. (January 2006). Amphibians of East Africa. Comstock Pub. Associates/Cornell University Press. pp. 104–117. ISBN 978-0-8014-4374-9. OCLC 60650905.
  35. ^ Vitt, L. J.; Caldwell, J. P. (25 March 2013). Herpetology: An Introductory Biology of Amphibians and Reptiles. Academic Press. p. 453. ISBN 978-0-12-386920-3. OCLC 898295183.