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 living families within the

Cryptobranchoidea The Cryptobranchoidea are a suborder of salamanders found in Asia, European Russia, and the United States. They are known as primitive salamanders, in contrast to Salamandroidea, the advanced salamanders. It has two living subdivisions, Cryptobra ...

, one of two main divisions of living salamanders, the other being the Asiatic salamanders belonging to the family Hynobiidae. The largest species are in the genus '' Andrias,'' native to east Asia''.'' The

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

(''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 The Japanese giant salamander (''Andrias japonicus'') is a species of fully aquatic giant salamander endemic to Japan. With a length of up to ,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 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 ...

(''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 Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic p ...

''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'' Ukraine,

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

** †'' Ukrainurus hypsognathus'' * Genus †''

Chunerpeton ''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 ...

?'' China, Middle Jurassic ** †'' Chunerpeton tianyiensis'' *Family Cryptobranchidae ** Genus ''Cryptobranchus'' (hellbenders) *** †'' Cryptobranchus saskatchewanensis?''

Ravenscrag Formation The Ravenscrag Formation is a stratigraphic unit of early Paleocene age in the Western Canada Sedimentary Basin. It was named for the settlement of Ravenscrag, Saskatchewan, and was first described from outcrops at Ravenscrag Butte near the Fr ...

, Canada, Paleocene *** '' Cryptobranchus alleganiensis'' (

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

Chinese giant salamander The Chinese giant salamander (''Andrias davidianus'') is one of the largest salamanders and one of the largest amphibians in the world.Simplified Chinese: ;

pinyin Hanyu Pinyin (), often shortened to just pinyin, is the official romanization system for Standard Chinese, Standard Mandarin Chinese in China, and to some extent, in Singapore and Malaysia. It is often used to teach Mandarin, normally writte ...

: ') (may actually be a

species complex In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...

of 5 different species) ***'' Andrias sligoi'' (

) ***'' Andrias japonicus'' (

Japanese giant salamander The Japanese giant salamander (''Andrias japonicus'') is a species of fully aquatic giant salamander endemic to Japan. With a length of up to ,Andrias jiangxiensis'' ( Jiangxi giant salamander) *** †'' Andrias matthewi'' North America, Miocene *** †'' Andrias scheuchzeri'' Europe, Oligocene- Pliocene ** Genus †'' Eoscapherpeton'' Central Asia, Late Cretaceous ( Cenomanian-

Campanian The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campani ...

) **Genus †'' Aviturus'' Mongolia, Paleocene *** †'' Aviturus exsecratus'' ** Genus †'' Ulanurus'' Mongolia, Paleocene *** †'' Ulanurus fractus'' ** Genus †'' Zaissanurus'' Kazakhstan, Oligocene *** †'' Zaissanurus beliajevae''

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 of China. ''

'' 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 cryptobranchoid not more closely related to Cryptobranchidae than to

Hynobiidae 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. ...

. The next oldest cryptobranchid is '' Eoscapherpeton'', known from numerous Late Cretaceous deposits in Central Asia, which is suggested to represent a

stem-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. ...

to modern cryptobranchids. Modern crown group 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 In biogeography, a land bridge is an isthmus or wider land connection between otherwise separate areas, over which animals and plants are able to cross and colonize new lands. A land bridge can be created by marine regression, in which sea leve ...

, with waves of adaptive radiation seeming to have swept the Americas from north to south. Andrias Scheuchzeri Oeningen

In 1726, the Swiss physician

Johann Jakob Scheuchzer Johann Jakob Scheuchzer (2 August 1672 – 23 June 1733) was a Swiss scholar born at Zürich. Herbarium deluvianum Zürich, Zwingli-Platz ( Grossmünster) : Former home of Konrad von Mure († 1280) and the house, where Johann Jakob Scheuch ...

described a fossil as ''Homo diluvii testis'' (

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

: 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,

Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...

, bought the fossil in 1802, where it is still exhibited. In 1812, the fossil was examined by Georges Cuvier, who recognized that it was not human. After being identified as a salamander, it was renamed '' Salamandra scheuchzeri'' by Holl in 1831. The

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

''Andrias'' was coined six years later by Tschudi. In doing so, both the genus, ''Andrias'' (which means "image of man"), and the specific name, ''scheuchzeri'', ended up honouring Scheuchzer and his beliefs. It and the extant ''A. davidianus'' cannot be mutually distinguished, and the latter, only described in 1871, is therefore sometimes considered a synonym 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 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 is a zoo in Hiroshima, Japan. Overview Asa Zoological Park opened in 1971 in Asakita-ku, Hiroshima as the 62nd zoo in Japan. The gross area of the zoo is 49.6 ha. There are about 170 varieties of animals including giraffes, lions, black rhino ...

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