The Cryptobranchidae are a family of fully aquatic salamanders commonly known as the giant salamanders. They include the largest living

amphibians Amphibians are four-limbed and ectothermic vertebrates of the class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terrestrial, fossorial, arbore ...

. The family is native to China, Japan, and the eastern United States. They constitute one of two living families within the Cryptobranchoidea, one of two main divisions of living salamanders, the other being the

Asiatic salamander The Asiatic salamanders (family Hynobiidae) are primitive salamanders found all over Asia, and in European Russia. They are closely related to the giant salamanders (family Cryptobranchidae), with which they form the suborder Cryptobranchoidea. ...

s belonging to the family Hynobiidae. The largest species are in the genus ''

Andrias ''Andrias'' is a genus of giant salamanders. It includes the largest salamanders in the world, with ''A. japonicus'' reaching a length of , and ''A. sligoi'' reaching . While extant species are only known from East Asia, several extinct species i ...

,'' native to east Asia''.'' The South China giant salamander (''Andrias sligoi''), can reach a length of .Andrias davidianus
AmphibiaWeb: Information on amphibian biology and conservation. 2012. Berkeley, California: AmphibiaWeb. Retrieved 13 December 2012. The Japanese giant salamander (''Andrias japonicus'') reaches up to in length, feeds at night on fish and crustaceans, and has been known to live for more than 50 years in captivity.Andrias japonicus
AmphibiaWeb: Information on amphibian biology and conservation. 2012. Berkeley, California: AmphibiaWeb. Retrieved 13 December 2012. The hellbender (''Cryptobranchus alleganiensis'') inhabits the eastern United States and is the only member of the genus ''Cryptobranchus''.

Taxonomy

The family name is from the Ancient Greek ''krypto'' ("hidden"), and ''branch'' ("gill"), which refer to how the members absorb oxygen through capillaries of their side-frills, which function as gills. Clade Pancryptobrancha (Cryptobranchidae + Ukrainurus) * Genus †''

Ukrainurus ''Ukrainurus'' is an extinct genus of pancryptobranchan urodelan known from the Miocene of Grytsiv locality, Ukraine. It contains a single species In biology, a species is the basic unit of classification and a taxonomic rank of an org ...

'' Ukraine, Miocene ** †''

Ukrainurus hypsognathus ''Ukrainurus'' is an extinct genus of pancryptobranchan urodelan known from the Miocene of Grytsiv locality, Ukraine. It contains a single species In biology, a species is the basic unit of classification and a taxonomic rank of an org ...

'' * Genus †'' Chunerpeton?'' China, Middle Jurassic ** †''

Chunerpeton tianyiensis ''Chunerpeton tianyiensis'' is an extinct species of salamander from the Late Jurassic Daohugou Beds in Ningcheng County, Nei Mongol (Inner Mongolia), China. It is the only species classified under the genus ''Chunerpeton''. It was a small anima ...

'' *Family Cryptobranchidae ** Genus ''Cryptobranchus'' (hellbenders) *** †''

Cryptobranchus saskatchewanensis The hellbender (''Cryptobranchus alleganiensis''), also known as the hellbender salamander, is a species of aquatic giant salamander endemic to the eastern and central United States. It is the largest salamander in North America. A member of th ...

?'' Ravenscrag Formation, Canada, Paleocene *** ''

Cryptobranchus alleganiensis The hellbender (''Cryptobranchus alleganiensis''), also known as the hellbender salamander, is a species of aquatic giant salamander endemic to the eastern and central United States. It is the largest salamander in North America. A member of the ...

'' ( hellbender) ** Genus ''

'' (Asian giant salamanders; sometimes classified among the ''Cryptobranchus'') ***''

Andrias davidianus The Chinese giant salamander (''Andrias davidianus'') is one of the largest salamanders and one of the largest amphibians in the world.Chinese giant salamander) – ( Simplified Chinese: ; pinyin: ') (may actually be a species complex of 5 different species) ***''

Andrias sligoi The South China giant salamander (''Andrias sligoi'') may be the largest species of salamander and the largest amphibian in the world. It is endemic to southern China, mainly in the Pearl River basin south of the Nanling Mountains. It is extremel ...

'' ( South China giant salamander) ***''

Andrias japonicus The Japanese giant salamander (''Andrias japonicus'') is a species of fully aquatic giant salamander endemic to Japan. With a length of up to ,Japanese giant salamander) – ( ja, オオサンショウウオ) ***''

Andrias jiangxiensis The Jiangxi giant salamander (''Andrias jiangxiensis'') is a species of very large salamander endemic to Jiangxi Province in China. It is the only Chinese ''Andrias'' species known to have a genetically pure wild population. Discovery and descr ...

'' (

Jiangxi giant salamander The Jiangxi giant salamander (''Andrias jiangxiensis'') is a species of very large salamander Endemism, endemic to Jiangxi, Jiangxi Province in China. It is the only Chinese ''Andrias'' species known to have a genetically pure wild population. ...

) *** †''

Andrias matthewi ''Andrias matthewi'', or Matthew's giant salamander, is an extinct species of giant salamander from the Miocene of North America. It belongs to the genus ''Andrias'', which contains the living Asian giant salamanders. It is the largest salamande ...

'' North America, Miocene *** †''

Andrias scheuchzeri ''Andrias scheuchzeri'' is an extinct species of giant salamander belonging to the genus ''Andrias'', which also contains the closely related living Asian giant salamanders. It is known from Oligocene to Pliocene aged deposits primarily from Cent ...

'' Europe,

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...

- Pliocene ** Genus †''

Eoscapherpeton ''Eoscapherpeton'' is an extinct genus of giant salamander, known from the Late Cretaceous of Central Asia. Fossils have been found in the Cenomanian aged Khodzhakul Formation and Dzharakuduk Formation, Turonian aged Bissekty Formation and the C ...

'' Central Asia, Late Cretaceous (

Cenomanian The Cenomanian is, in the ICS' geological timescale, the oldest or earliest age of the Late Cretaceous Epoch or the lowest stage of the Upper Cretaceous Series. An age is a unit of geochronology; it is a unit of time; the stage is a unit in the s ...

- Campanian) **Genus †''

Aviturus The Cryptobranchidae are a family of fully aquatic salamanders commonly known as the giant salamanders. They include the largest living amphibians. The family is native to China, Japan, and the eastern United States. They constitute one of two l ...

'' Mongolia, Paleocene *** †''

Aviturus exsecratus The Cryptobranchidae are a family of fully aquatic salamanders commonly known as the giant salamanders. They include the largest living amphibians. The family is native to China, Japan, and the eastern United States. They constitute one of two l ...

'' ** Genus †''

Ulanurus The Cryptobranchidae are a family of fully aquatic salamanders commonly known as the giant salamanders. They include the largest living amphibians. The family is native to China, Japan, and the eastern United States. They constitute one of two l ...

'' Mongolia, Paleocene *** †''

Ulanurus fractus The Cryptobranchidae are a family of fully aquatic salamanders commonly known as the giant salamanders. They include the largest living amphibians. The family is native to China, Japan, and the eastern United States. They constitute one of two li ...

'' ** Genus †''

Zaissanurus The Cryptobranchidae are a family of fully aquatic salamanders commonly known as the giant salamanders. They include the largest living amphibians. The family is native to China, Japan, and the eastern United States. They constitute one of two l ...

'' Kazakhstan,

*** †''

Zaissanurus beliajevae The Cryptobranchidae are a family of fully aquatic salamanders commonly known as the giant salamanders. They include the largest living amphibians. The family is native to China, Japan, and the eastern United States. They constitute one of two l ...

Fossil record

Extant species in the family Cryptobranchidae are the modern-day members of a lineage that extends back tens millions of years. The oldest known fossils of cryptobranchoids are known from the

Middle Jurassic The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from about 174.1 to 163.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relatively rare, but geological formations co ...

of China. '' Chunerpeton'' from the Middle Jurassic of China has been suggested to represent the oldest known cryptobranchid. However, some studies have found it to be a more

basal Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''. Science * Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure * Basal (medicine), a minimal level that is nec ...

cryptobranchoid not more closely related to Cryptobranchidae than to Hynobiidae. The next oldest cryptobranchid is ''

'', known from numerous Late Cretaceous deposits in Central Asia, which is suggested to represent a stem-group to modern cryptobranchids. Modern

crown group In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. ...

representatives appear during the Paleocene. As the fossil record for the Cryptobranchidae shows an Asian origin for the family, how these salamanders made it to the eastern US has been a point of scientific interest. Research has indicated a dispersal via land bridge, with waves of

adaptive radiation In evolutionary biology, adaptive radiation is a process in which organisms diversify rapidly from an ancestral species into a multitude of new forms, particularly when a change in the environment makes new resources available, alters biotic int ...

seeming to have swept the Americas from north to south. Andrias Scheuchzeri Oeningen

In 1726, the Swiss physician Johann Jakob Scheuchzer described a fossil as ''Homo diluvii testis'' ( Latin: Evidence of a diluvian human), believing it to be the remains of a human being who drowned in the biblical flood. The Teylers Museum in

Haarlem Haarlem (; predecessor of ''Harlem'' in English) is a city and municipality in the Netherlands. It is the capital of the province of North Holland. Haarlem is situated at the northern edge of the Randstad, one of the most populated metropoli ...

, Netherlands, bought the fossil in 1802, where it is still exhibited. In 1812, the fossil was examined by

Georges Cuvier Jean Léopold Nicolas Frédéric, Baron Cuvier (; 23 August 1769 – 13 May 1832), known as Georges Cuvier, was a French natural history, naturalist and zoology, zoologist, sometimes referred to as the "founding father of paleontology". Cuvier ...

, who recognized that it was not human. After being identified as a salamander, it was renamed ''

Salamandra ''Salamandra'' is a genus of seven species of salamanders localized in central and southern Europe, Northern Africa, and western Asia. List of species References External links Salamandraat Fauna Europaea * Salamandraat Animal Diversity W ...

scheuchzeri'' by Holl in 1831. The genus ''Andrias'' was coined six years later by

Tschudi Tschudi (variants: Schudy, Shoudy, Shudi, Schudi, Tschudy) is a surname common in the Canton of Glarus, Switzerland. History The Tschudi name can be traced back to 870. After Glarus joined the Swiss Confederation in 1352, various members of the fa ...

. In doing so, both the genus, ''Andrias'' (which means "image of man"), and the

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

, ''scheuchzeri'', ended up honouring Scheuchzer and his beliefs. It and the

extant Extant is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Extant taxon, a taxon which is not extinct, ...

''A. davidianus'' cannot be mutually distinguished, and the latter, only described in 1871, is therefore sometimes considered a

synonym A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are all ...

of the former.

Description

Cryptobranchids are large salamanders, with large folds of skin along their flanks. These help increase the animals' surface area, allowing them to absorb more oxygen from the water. They have four toes on the fore limbs, and five on the hind limbs. They have paedomorphic traits, meaning their

metamorphosis Metamorphosis is a biological process by which an animal physically develops including birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some inse ...

from the larval stage is incomplete, so the adults retain gill slits (although they also have lungs), and lack eyelids. They have a stout body with a heavy, laterally compressed tail. They have bad eyesight. They can reach a length of , though most are considerably smaller today.

Distribution and habitat

In Japan, their natural habitats are threatened by dam-building. Ramps and staircases have been added to some dams to allow them to move upstream to areas where they spawn. "Giant Salamanders Helped to Spawn"
31 December 2009. National Geographic Society. Retrieved 13 December 2012.

Behavior

A Japanese giant salamander lived for 52 years in captivity.

Feeding

The Chinese giant salamander eats aquatic insects, fish, frogs, crabs, and shrimp. They hunt mainly at night. As they have poor eyesight, they use sensory nodes on their heads and bodies to detect minute changes in water pressure, enabling them to find their prey.

Reproduction

During mating season, the salamanders travel upstream, where the female lays two strings of over 200 eggs each. Lacking the stereotypical courtship behaviors found in other species, the male fertilizes the eggs externally by releasing his sperm onto them, and then guards them for at least three months, until they hatch. Tail fanning also occurs in order to increase the oxygen supply for the eggs. At this point, the larvae live off their noticeable stored fat until ready to hunt. Once ready, they hunt as a group rather than individually. Scientists at Hiroshima City Asa Zoological Park in Japan have recently discovered the male salamander will spawn with more than one female in his den. Only large males can occupy and guard a den. They guard the den against other males and sexually inactive females. Those that are sexually active are welcomed. On occasion, the male "den master" will also allow a second male (smaller male salamanders, named "satellite males", who do not have their own den) into the den; the reason for this is unclear.Okada, Sumio, Yukihiro Fukuda, and Mizuki K. Takahashi. "Paternal care behaviors of Japanese giant salamander Andrias japonicus in natural populations." Journal of ethology 33.1 (2015): 1-7.

References

External links

BBC article with video on Giant salamanders from JapanCryptobranchid Interest Group

Tree of Life: CryptobranchidaeChinese Giant SalamanderJapanese Giant Salamander
{{Taxonbar, from=Q754032 Cryptobranchoidea Extant Middle Jurassic first appearances Taxa named by Leopold Fitzinger