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The Trionychidae are a taxonomic
family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...
of a number of
turtle Turtles are an order of reptiles known as Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked t ...
genera 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 nomenclat ...
, commonly known as softshell turtles. The family was erected by
Leopold Fitzinger Leopold Joseph Franz Johann Fitzinger (13 April 1802 – 20 September 1884) was an Austrian zoologist. Fitzinger was born in Vienna and studied botany at the University of Vienna under Nikolaus Joseph von Jacquin. He worked at the Vienna Natur ...
in 1826. Softshells include some of the world's largest freshwater turtles, though many can adapt to living in highly
brackish Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estua ...
areas. Members of this family occur in Africa, Asia, and North America, with extinct species known from
Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...
. Most species have traditionally been included in the genus '' Trionyx'', but the vast majority have since been moved to other genera. Among these are the North American '' Apalone'' softshells that were placed in ''Trionyx'' until 1987.


Characteristics

They are called "softshell" because their
carapace A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the unde ...
s lack horny
scute A scute or scutum (Latin: ''scutum''; plural: ''scuta'' "shield") is a bony external plate or scale overlaid with horn, as on the shell of a turtle, the skin of crocodilians, and the feet of birds. The term is also used to describe the anterior po ...
s (scales), though the spiny softshell, '' Apalone spinifera'', does have some scale-like projections, hence its name. The carapace is leathery and pliable, particularly at the sides. The central part of the carapace has a layer of solid bone beneath it, as in other turtles, but this is absent at the outer edges. Some species also have dermal bones in the plastron, but these are not attached to the bones of the shell. The light and flexible shell of these turtles allows them to move more easily in open water or in muddy lake bottoms. Having a soft shell also allows them to move much faster on land than most turtles. Their feet are webbed and three-clawed, hence the family name "Trionychidae," which means "three-clawed". The carapace color of each type of softshell turtle tends to match the sand or mud color of its geographical region, assisting in their "lie in wait" feeding methodology. These turtles have many characteristics pertaining to their aquatic lifestyle. Many must be submerged in order to swallow their food. They have elongated, soft, snorkel-like nostrils. Their necks are disproportionately long in comparison to their body sizes, enabling them to breathe surface air while their bodies remain submerged in the substrate (mud or sand) a foot or more below the surface. Females can grow up to several feet in carapace diameter, while males stay much smaller; this is their main form of
sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most an ...
. '' Pelochelys cantorii'', found in southeastern Asia, is the largest softshell turtle. Most are strict carnivores, with diets consisting mainly of fish, aquatic crustaceans, snails, amphibians, and sometimes birds and small mammals. Softshells are able to "breathe" underwater with rhythmic movements of their mouth cavity, which contains numerous processes copiously supplied with blood, acting similarly to gill filaments in fish. This enables them to stay underwater for prolonged periods. Moreover, the Chinese softshell turtle has been shown to excrete
urea Urea, also known as carbamide, is an organic compound with chemical formula . This amide has two amino groups (–) joined by a carbonyl functional group (–C(=O)–). It is thus the simplest amide of carbamic acid. Urea serves an important ...
while "breathing" underwater; this is an efficient solution when the animal does not have access to fresh water, e.g., in brackish-water environments. According to Ditmars (1910): "The mandibles of many species form the outer border of powerful crushing processes—the alveolar surfaces of the jaws", which aids the ingestion of tough prey such as molluscs. These jaws make large turtles dangerous, as they are capable of amputating a person's finger, or possibly their hand. Unlike the temperature-dependent sex determination of most turtles, Trionychids have ZZ/ZW genetic sex determination;
microchromosome A microchromosome (μChr) is a type of very small chromosome which is a typical component of the karyotype of birds, some reptiles, fish, and amphibians; they have yet to be found in mammals. They are less than 20 Mb in size; chromosomes wh ...
s play a role in determining sex.


As food


In East Asia

Softshell turtles are eaten as a
delicacy A delicacy is usually a rare and expensive food item that is considered highly desirable, sophisticated, or peculiarly distinctive within a given culture. Irrespective of local preferences, such a label is typically pervasive throughout a r ...
in most parts of their range, particularly in East Asia. A Chinese dish
stew A stew is a combination of solid food ingredients that have been cooked in liquid and served in the resultant gravy. A stew needs to have raw ingredients added to the gravy. Ingredients in a stew can include any combination of vegetables a ...
s them with
chicken The chicken (''Gallus gallus domesticus'') is a domesticated junglefowl species, with attributes of wild species such as the grey and the Ceylon junglefowl that are originally from Southeastern Asia. Rooster or cock is a term for an adu ...
. According to a 1930 report by Soame Jenyns,
Guangdong Guangdong (, ), alternatively romanized as Canton or Kwangtung, is a coastal province in South China on the north shore of the South China Sea. The capital of the province is Guangzhou. With a population of 126.01 million (as of 2020 ...
restaurants had them imported from
Guangxi Guangxi (; ; alternately romanized as Kwanghsi; ; za, Gvangjsih, italics=yes), officially the Guangxi Zhuang Autonomous Region (GZAR), is an autonomous region of the People's Republic of China, located in South China and bordering Vietnam ...
in large numbers; "eaten stewed with almonds, roast with chili sauce or fried with bamboo shoots, they ereconsidered a great delicacy." Worldwide, the most commonly consumed softshell species is the Chinese softshell ''
Pelodiscus sinensis The Chinese softshell turtle (''Pelodiscus sinensis'') is a species of softshell turtle that is native to China ( Inner Mongolia to Guangxi, including Hong Kong) and Taiwan, with records of escapees—some of which have established introdu ...
''. As a noted Japanese biologist pointed out in 1904, the Japanese variety of this turtle, which at time was classified as ''Trionyx japonicus'', occupied a place in Japanese cuisine as esteemed as the diamondback terrapin in the United States or the
green turtle The green sea turtle (''Chelonia mydas''), also known as the green turtle, black (sea) turtle or Pacific green turtle, is a species of large sea turtle of the family Cheloniidae. It is the only species in the genus ''Chelonia''. Its range exten ...
in England. The
farming Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled peopl ...
of this "luscious reptile", known in Japan as ''suppon'', was already developed on an industrial scale in that country by the late 19th century. Due to rising demand and overhunting, the price of ''Pelodiscus sinensis'' in China skyrocketed by the mid-1990s; large-scale
turtle farming Turtle farming is the practice of raising turtles and tortoises of various species commercially. Raised animals are sold for use as gourmet food, traditional medicine ingredients, or as pets. Some farms also sell young animals to other farms, ...
in China and neighboring countries; raising this species by hundreds of millions was the response, with prices soon returning to a more affordable level.Zhang Jian (章剑)
Chinese soft-shelled turtle value return
, ''Turtle news'' (中国龟鳖网), 13 August 2009 (appears to be a machine translation of the more comprehensible "中华鳖价值回归", at )
Also at http://sites.google.com/site/jfparham/2008Shi.pdf Another species, ''
Palea steindachneri The wattle-necked softshell turtle (''Palea steindachneri''), also commonly known as Steindachner's soft-shelled turtle, is an endangered Asian species of softshell turtle in the family Trionychidae. The species is the only member of the genus ' ...
'', is farmed in China, as well, but on a much smaller scale (with farm herds measured in hundreds of thousands, rather than hundreds of millions).


In the United States

In the United States, harvesting softshells (e.g. ''
Apalone ferox The Florida softshell turtle (''Apalone ferox'') is a species of softshell turtle native to the Southeastern United States.Rafinesque, Constantine S. "12. Description of two new genera of Soft Shell Turtles of North America." Atlantic Journal, a ...
'') was, until recently, legal in
Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and ...
. Environmental groups have been advocating the authorities' banning or restricting the practice. The
Florida Fish and Wildlife Conservation Commission The Florida Fish and Wildlife Conservation Commission (FWC) is a Florida government agency founded in 1999 and headquartered in Tallahassee. It manages and regulates the state's fish and wildlife resources, and enforces related laws. Officers ar ...
responded by introducing the daily limit of 20 turtles for licensed harvesters—a level which the turtle advocates consider unsustainable, as there may be between 100 and 500 hunters statewide. While some catch was consumed locally, most was exported; the Commission estimated (2008) around 3,000 pounds of softshell turtles were exported each week via
Tampa International Airport Tampa International Airport is an international airport west of Downtown Tampa, in Hillsborough County, Florida, United States. The airport is publicly owned by Hillsborough County Aviation Authority (HCAA)., effective December 30, 2021. T ...
. New rules, in effect as of July 20, 2009, restrict collecting any wild turtles to one turtle per person per day, completely prohibit collection of softshells ('' Apalone'') in May through July, and prohibit trade in turtles caught from the wild. An exemption is provided for licensed turtle farms that need to catch turtles in the wild to serve as their breeding stock. Some other US states, too, have already adopted strict limitations on wild turtle trade. In 2009,
South Carolina )''Animis opibusque parati'' ( for, , Latin, Prepared in mind and resources, links=no) , anthem = " Carolina";" South Carolina On My Mind" , Former = Province of South Carolina , seat = Columbia , LargestCity = Charleston , LargestMetro = ...
passed a law (Bill H.3121) restricting interstate and international export of wild-caught turtles (both soft-shell and some other species) to 10 turtles per person at one time, and 20 turtles per person per year.


Taxonomy

Family Trionychidae *'' Palaeotrionyx'' (fossil) ''Paleotrionyx jimenezfuentesi'' *Subfamily Plastomeninae (fossil) **Genus '' Gilmoremys'' **Genus '' Hutchemys'' **Genus '' Plastomenus'' *Subfamily Cyclanorbinae **Genus '' Cyclanorbis'' **Genus '' Cycloderma'' **Genus '' Lissemys'' *Subfamily Trionychinae **Genus '' Amyda'', Amyda menneri **Genus '' Apalone'' **Genus '' Chitra'', Chitra minor **Genus '' Dogania'' **Genus '' Nilssonia'' **Genus '' Palea'' **Genus '' Pelochelys'' **Genus ''
Pelodiscus ''Pelodiscus'' is a genus of turtles in the family Trionychidae, the softshells. Based on genetic and morphological analysis there are seven valid species. They are native to Eastern Asia, ranging from the Amur region, south through China and K ...
'' **Genus ''
Rafetus ''Rafetus'' is a genus of highly endangered softshell turtles in the family Trionychidae. It is a genus of large turtles which are found in freshwater habitats in Asia. Species According to most taxonomists, the genus ''Rafetus'' contains the fo ...
'' **Genus '' Trionyx''


Past classification

*Genus ''
Aspideretes ''Nilssonia'' is a genus of softshell turtles (family Trionychidae) from rivers, streams, ponds, and lakes in South Asia and Burma. In many treatments, it is monotypic, with the single species Burmese peacock softshell (''N. formosa''). However, ...
''


Phylogeny

Cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...
after Walter G. Joyce, Ariel Revan, Tyler R. Lyson and Igor G. Danilov (2009).


Gallery

File:Amyd cartil 090818-11752 tsa.jpg, '' Amyda cartilaginea'' (juvenile) File:Floridasoftshellturtle-cropped.jpg, ''
Apalone ferox The Florida softshell turtle (''Apalone ferox'') is a species of softshell turtle native to the Southeastern United States.Rafinesque, Constantine S. "12. Description of two new genera of Soft Shell Turtles of North America." Atlantic Journal, a ...
'' File:Eastern Spiny Softshell Turtle.jpg, '' Apalone spinifera'' File:Dudhwalive chitra.JPG, ''
Chitra indica The Indian narrow-headed softshell turtle (''Chitra indica''), also known as the small-headed softshell turtle or the Indo-Gangetic softshell turtle, is an endangered species of softshell turtle native to waterways and rivers of the Indian subc ...
'' File:Dogan subplan100117-0332 ipb.jpg, '' Dogania subplana'' File:(Lissemys punctata) Indian flap shell Turtle 04.JPG, '' Lissemys punctata'' File:Bostami Turtle.jpg, ''
Nilssonia nigricans The black softshell turtle or Bostami turtle (''Nilssonia nigricans''), previously placed in genus '' Aspideretes'', is a species of freshwater turtle found in India (Assam and Tripura) and Bangladesh ( Chittagong and Sylhet). It was long bel ...
'' File:Pelochelys cantorii.jpg, '' Pelochelys cantorii'' File:E8976-Namdaemun-Turtles-sold-in-ginseng-shop.jpg, ''
Pelodiscus sinensis The Chinese softshell turtle (''Pelodiscus sinensis'') is a species of softshell turtle that is native to China ( Inner Mongolia to Guangxi, including Hong Kong) and Taiwan, with records of escapees—some of which have established introdu ...
'' in a
Seoul Seoul (; ; ), officially known as the Seoul Special City, is the Capital city, capital and largest metropolis of South Korea.Before 1972, Seoul was the ''de jure'' capital of the North Korea, Democratic People's Republic of Korea (North Korea ...
market File:Rafetus euphraticus cropped.jpg, '' Rafetus euphraticus'' File:Rùa Đồng Mô.jpg, ''
Rafetus swinhoei The Yangtze giant softshell turtle (''Rafetus swinhoei''), also known as the Red River giant softshell turtle, the Shanghai softshell turtle, the speckled softshell turtle, and Swinhoe's softshell turtle, is an extremely rare species of turtle ...
'' File:Ab reptile 05.jpg, '' Trionyx triunguis''


Notes


References


Trionychidae
(all species) a
The Reptile Database
*Parade of the Animal Kingdom. Hegner, Robert. 1935. the Macmillan Company. {{Authority control Turtle families Taxa named by Leopold Fitzinger