The Cryptobranchidae (commonly known as giant salamanders) are a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

of large

salamander Salamanders are a group of amphibians typically characterized by their lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. All t ...

s that are fully aquatic. The family includes some of the largest living

amphibians Amphibians are ectothermic, anamniote, anamniotic, tetrapod, four-limbed vertebrate animals that constitute the class (biology), class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all Tetrapod, tetrapods, but excl ...

. They are native to China, Japan, and the eastern United States. Giant salamanders constitute one of two living families—the other being the Asiatic salamanders belonging to the family Hynobiidae—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, Cryptobr ...

, one of two main divisions of living salamanders. 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 known only from East Asia, several extinct species ...

'', 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

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

s, 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 Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), 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'' 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'', which means "early ...

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

Paleocene The Paleocene ( ), or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), ...

*** '' Cryptobranchus alleganiensis'' ( hellbender) ** Genus ''

'' (Asian giant salamanders; sometimes classified among the ''Cryptobranchus'') ***'' Andrias cheni'' (Qimen giant salamander) ***'' 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 Simplification, Simplify, or Simplified may refer to: Mathematics Simplification is the process of replacing a mathematical expression by an equivalent one that is simpler (usually shorter), according to a well-founded ordering. Examples include: ...

: ;

pinyin Hanyu Pinyin, or simply pinyin, officially the Chinese Phonetic Alphabet, is the most common romanization system for Standard Chinese. ''Hanyu'' () literally means 'Han Chinese, Han language'—that is, the Chinese language—while ''pinyin' ...

: ') (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'' ( South China giant salamander) ***'' Andrias japonicus'' ( Japanese giant salamander) – () ***'' Andrias jiangxiensis'' ( Jiangxi giant salamander) *** †'' Andrias matthewi'' North America, Miocene *** †'' Andrias scheuchzeri'' Europe,

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58Eoscapherpeton'' Central Asia, Late Cretaceous (

Cenomanian The Cenomanian is, in the International Commission on Stratigraphy's (ICS) geological timescale, the oldest or earliest age (geology), age of the Late Cretaceous epoch (geology), Epoch or the lowest stage (stratigraphy), stage of the Upper Cretace ...

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. Campa ...

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

*** †'' Zaissanurus beliajevae''

Phylogeny

The following phylogeny is based on Vasilyan ''et al''. (2013): The well-represented Cretaceous '' Eoscapherpeton'' was not phylogenetically placed. The enigmatic "''Cryptobranchus''" ''saskatchewanensis'' of Paleocene Canada may actually represent a stem-cryptobranchid.

Description

Cryptobranchids are large and predominantly nocturnal

s that can reach a length of , though most are considerably smaller today. Despite being aquatic, they are poor swimmers and mostly just walk on the bottom. Swimming by undulatory locomotion is generally used just for short distance-escapes to hiding places. The body is stout with large folds of skin along the flanks and a heavy, laterally compressed tail. These folds help increase the animals' surface area, allowing them to absorb more oxygen from the water as the adults lacks gills and have poorly developed lungs. Like in the majority of salamander species, there are 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 transformation or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and different ...

from the larval stage is incomplete, so they lack eyelids and the adults retain gill slits (open in the hellbender, closed in Andrias). Eyes are small and the eyesight bad.

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.

Fossil record

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

Middle Jurassic The Middle Jurassic is the second Epoch (geology), epoch of the Jurassic Period (geology), Period. It lasted from about 174.1 to 161.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relativel ...

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 next oldest cryptobranchid is '' Eoscapherpeton'', known from numerous

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

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 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

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 le ...

, 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. In 1726, the Swiss physician Johann Jakob Scheuchzer described a fossil as ''Homo diluvii testis'' (

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

: Evidence of a diluvian human), believing it to be the remains of a human being who drowned in the biblical

flood A flood is an overflow of water (list of non-water floods, or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are of significant con ...

. The

Teylers Museum Teylers Museum () is an Art museum, art, Natural history museum, natural history, and science museum in Haarlem, Netherlands. Established in 1778, Teylers Museum was founded as a centre for contemporary art and science. The historic centre of the ...

Haarlem Haarlem (; predecessor of ''Harlem'' in English language, English) is a List of cities in the Netherlands by province, city and Municipalities of the Netherlands, municipality in the Netherlands. It is the capital of the Provinces of the Nether ...

Netherlands , Terminology of the Low Countries, informally Holland, is a country in Northwestern Europe, with Caribbean Netherlands, overseas territories in the Caribbean. It is the largest of the four constituent countries of the Kingdom of the Nether ...

, 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". Cuv ...

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

Salamandra ''Salamandra'' is a genus of six 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 We ...

scheuchzeri'' by Holl in 1831. The

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

''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 Extant or Least-concern species, least concern 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 * Exta ...

''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 precisely 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 a ...

of the former.

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 Extant Middle Jurassic first appearances Taxa named by Leopold Fitzinger