Trionychidae

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Trionychidae
Temporal range: Early Cretaceous–Present
Pelodiscus.jpg
Chinese softshell turtle
Pelodiscus sinensis
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Testudines
Suborder: Cryptodira
Superfamily: Trionychia
Clade: Pan-Trionychidae
Joyce et al., 2004
Family: Trionychidae
Fitzinger, 1826
Subfamilies

Trionychidae is a family of turtles, commonly known as softshell turtles or simply softshells. The family was described by Leopold Fitzinger in 1826. Softshells include some of the world's largest freshwater turtles, though many can adapt to living in highly brackish waters. Members of this family occur in Africa, Asia, and North America, with extinct species known from Australia. [2] 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. [3]

Contents

Characteristics

Turtles of the family Trionychidae are called "softshell" because their carapaces lack horny scutes (scales), though the spiny softshell, Apalone spinifera , does have some scale-like projections, to which its common name refers. 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. [4] 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. [5] 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. Pelochelys cantorii , found in southeastern Asia, is the largest softshell turtle.

Head and neck of Pelodiscus sinensis Pelodiscus-head.jpg
Head and neck of Pelodiscus sinensis

Most are strict carnivores, with diets consisting mainly of fish, aquatic crustaceans, snails, amphibians, [4] 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. [6] This enables them to stay underwater for prolonged periods. Moreover, the Chinese softshell turtle has been shown to excrete urea while "breathing" underwater; this is an efficient solution when the animal does not have access to fresh water, e.g., in brackish-water environments. [7]

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. [8]

Unlike the temperature-dependent sex determination of most turtles, Trionychids have ZZ/ZW genetic sex determination; microchromosomes play a role in determining sex. [9]

As food

Japanese suppon-nabe made from softshell turtle Kyoo Suppon Soup.jpg
Japanese suppon-nabe made from softshell turtle

In East Asia

Softshell turtles are eaten as a delicacy in most parts of their range, particularly in East Asia. A Chinese dish stews them with chicken. According to a 1930 report by Soame Jenyns, Guangdong restaurants had them imported from Guangxi in large numbers; "eaten stewed with almonds, roast with chili sauce or fried with bamboo shoots, they [were] considered a great delicacy." [10]

Worldwide, the most commonly consumed softshell species is the Chinese softshell Pelodiscus sinensis . 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 in England. The farming of this "luscious reptile", known in Japan as suppon, was already developed on an industrial scale in that country by the late 19th century. [11]

Due to rising demand and overhunting, the price of Pelodiscus sinensis in China skyrocketed by the mid-1990s; large-scale turtle farming in China and neighboring countries; raising this species by hundreds of millions was the response, with prices soon returning to a more affordable level. [12] [13] [14] Another species, Palea steindachneri , 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). [14]

In the United States

In the United States, harvesting softshells (e.g. Apalone ferox ) was, until recently, legal in Florida. Environmental groups have been advocating the authorities' banning or restricting the practice. The Florida Fish and Wildlife Conservation Commission 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 to China each week via Tampa International Airport. [15]

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. [16]

Some other US states, too, have already adopted strict limitations on wild turtle trade. In 2009, South Carolina 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. [17]

Taxonomy

Fossil of Plastomenus sp. in the Field Museum of Natural History, Chicago Plastomenus sp.jpg
Fossil of Plastomenus sp. in the Field Museum of Natural History, Chicago

Family Trionychidae

Past classification

Phylogeny

The following cladogram shows the relationships among the species: [19]

 Trionychidae 

Related Research Articles

<span class="mw-page-title-main">Asian giant softshell turtle</span> Species of freshwater turtle

The Asian giant softshell turtle, also known commonly as Cantor's giant softshell turtle and the frog-faced softshell turtle, is a species of freshwater turtle in the family Trionychidae. The species is native to Southeast Asia. The species is critically endangered and in the 20th century has disappeared from much of its former range.

<i>Staurotypus</i> Genus of turtles

Staurotypus is a genus of aquatic turtles, commonly known as giant musk turtles, Mexican musk turtles, or three-keeled musk turtles, in the family Kinosternidae. The genus contains two recognized species, which are endemic to Mexico and Central America. Both species are sold and bred as pets.

<span class="mw-page-title-main">Wattle-necked softshell turtle</span> Species of turtle

The wattle-necked softshell turtle, 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 Palea.

<i>Pelochelys</i> Genus of turtles

Pelochelys is a genus of very large softshell turtles in the family Trionychidae. They are found from peninsular India northeast to southern China, and south to Southeast Asia and New Guinea.These turtles are also known as Giant softshell turtles.

<span class="mw-page-title-main">Chinese softshell turtle</span> Species of turtle

The Chinese softshell turtle is a species of softshell turtle that is native to mainland China and Taiwan, with records of escapees—some of which have established introduced populations—in a wide range of other Asian countries, as well as Spain, Brazil and Hawaii.

<i>Apalone</i> Genus of turtles

Apalone is a genus of turtles in the family Trionychidae. The three species of Apalone are native to freshwater habitats in North America; they are the only living softshell turtles from the Americas.

<span class="mw-page-title-main">Trionychia</span> Superfamily of turtles

Trionychia is a superfamily of turtles which encompasses the species that are commonly referred to as softshelled turtles as well as some others. The group contains two families, Carettochelyidae, which has only one living species, the pig-nosed turtle native to New Guinea and Northern Australia, and Trionychidae, the softshelled turtles, containing numerous species native to Asia, North America and Africa. These families likely diverged during the late Jurassic. The oldest known stem-trionychian is Sinaspideretes from the Late Jurassic of China.

<span class="mw-page-title-main">Spiny softshell turtle</span> Species of turtle

The spiny softshell turtle is a species of softshell turtle, one of the largest freshwater turtle species in North America. Both the common name, spiny softshell, and the specific name, spinifera (spine-bearing), refer to the spiny, cone-like projections on the leading edge of the carapace, which are not scutes (scales).

<span class="mw-page-title-main">Northern spiny softshell turtle</span> Subspecies of turtle

The northern spiny softshell turtle is a subspecies of soft-shelled turtle in the family Trionychidae. The subspecies is native to the United States and can be found from Montana at the western edge of its range to Vermont and Quebec on the eastern edge. Introduced populations have also been found in Massachusetts, New Jersey, Arizona, and Virginia.

<span class="mw-page-title-main">Gulf Coast spiny softshell turtle</span> Subspecies of turtle

The Gulf Coast spiny softshell turtle, a subspecies in the Trionychidae family of softshell turtles, is endemic to the south-eastern United States.

<span class="mw-page-title-main">Florida softshell turtle</span> Species of turtle

The Florida softshell turtle is a species of turtle in the family Trionychidae. The species is native to the Southeastern United States.

<span class="mw-page-title-main">Yangtze giant softshell turtle</span> Critically endangered species of turtle

The Yangtze giant softshell turtle, also known commonly 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 in the family Trionychidae. It may be the largest living freshwater turtle in the world. The species is native to eastern and southern China and northern Vietnam. With a known population of only two or three individuals, and with the last known females dying out, this species is considered functionally extinct.

<span class="mw-page-title-main">Cuatro Cienegas softshell</span> Subspecies of turtle

The Cuatro Ciénegas softshell, also called the black spiny softshell, is a subspecies of the spiny softshell turtle in the family Trionychidae. It is found only in the Cuatro Ciénegas Basin in the Mexican state of Coahuila and it is considered critically endangered by the IUCN. The subspecies, along with its parent species, was formerly classified in the genus Trionyx.

<span class="mw-page-title-main">Malayan softshell turtle</span> Species of turtle

The Malayan softshell turtle is a species of softshell turtle in the family Trionychidae. It is monotypic in its genus.

The southern New Guinea giant softshell turtle is a species of softshell turtle in the family Trionychidae. The species is endemic to the lowlands of southern New Guinea with occasional vagrant individuals sighted off the coast of northern Australia. There is no confirmed Australian record. P. bibroni is referred to by the Suki people as kiya eise, a reference to its flexible shell. In the Arammba language, it is called sokrere, meaning "earthquake". It is sometimes hunted by local villages for its meat and/or eggs, leading to some cases of chelonitoxism.

<span class="mw-page-title-main">Smooth softshell turtle</span> Species of turtle

The smooth softshell turtle is a species of North American softshell turtle in the family Trionychidae. This freshwater species is endemic to the United States, where it inhabits the Mississippi River system, along with other adjoining waterways that empty into the Gulf of Mexico.

<span class="mw-page-title-main">Euphrates softshell turtle</span> Species of turtle

The Euphrates softshell turtle, also known as the Mesopotamian softshell turtle, is a species of softshell turtle in the family Trionychidae. It is found throughout much of the Euphrates–Tigris river basin in Iraq, Syria, Turkey and Khūzestān Province of Iran. Historically it has also been reported from Iran, but this likely involves confusion with the very similar Trionyx triunguis.

<span class="mw-page-title-main">Trionychinae</span> Subfamily of turtles

The Trionychinae are a subfamily of turtles in the family Trionychidae.

<span class="mw-page-title-main">Amur softshell turtle</span> Species of turtle

Pelodiscus maackii, commonly known as the Amur softshell turtle or the northern Chinese softshell turtle, is a species of turtle in the family Trionychidae. The species is found in the Russian Far East, northeastern China, Korea, and Japan. It is possible that the Japanese populations are the result of ancient introductions by humans. This aquatic species may attain a straight carapace length of 32.5 cm (1.1 ft).

<i>Rafetus bohemicus</i> Species of turtle

Rafetus bohemicus is an extinct species of softshell turtle from the Early Miocene (Burdigalian) of the Czech Republic. Specimens have been found at the northeastern margin of the Most Basin at a fossil site called Břešt’any. Fossil carapaces of "R. pontanus", a potential taxonomic synonym, have been found in slightly younger rocks in Lom and Louka u Litvínova.

References

  1. ↑ Chelonia.org
  2. ↑ Rule, James P.; Kool, Lesley; Parker, William M.G.; Fitzgerald, Erich M.G. (2021). "Turtles all the way down: Neogene pig-nosed turtle fossil from southern Australia reveals cryptic freshwater turtle invasions and extinctions". Papers in Palaeontology. 8. doi:10.1002/spp2.1414. S2CID   245107305.
  3. ↑ Meylan, P.A. (1987). "The phylogenetic relationships of soft-shelled turtles (Family Trionychidae)". Bulletin of the American Museum of Natural History186: 1–101.
  4. 1 2 Obst, Fritz Jürgen (1998). Cogger, H.G.; Zweifel, R.G. (eds.). Encyclopedia of Reptiles and Amphibians. San Diego: Academic Press. pp. 117–118. ISBN   978-0-12-178560-4.
  5. ↑ About Turtles and Tortoises, Chelonians
  6. ↑ Gage, Simon H.; Gage, Susanna Phelps (1886). "Aquatic respiration in soft-shelled turtles: A contribution to the physiology of respiration in vertebrates". American Naturalist. 20 (3): 233–236. Bibcode:1886ANat...20..233G. doi: 10.1086/274187 . JSTOR   2449924.
  7. ↑ Ip, Yuen K.; Loong, Ai M.; Lee, Serene M.L.; Ong, Jasmine L.Y.; Wong, Wai P.; Chew, Shit F. (2012). "The Chinese soft-shelled turtle, Pelodiscus sinensis, excretes urea mainly through the mouth instead of the kidney". Journal of Experimental Biology. 215 (21): 3723–33. Bibcode:2012JExpB.215.3723I. doi: 10.1242/jeb.068916 . PMID   23053366.
  8. ↑ Ditmars, Raymond Lee (1910). Reptiles of the World: Tortoises and Turtles, Crocodilians, Lizards and Snakes of the Eastern and Western Hemispheres. New York: Sturgis & Walton. pp.  55. ISBN   978-1112357510.
  9. ↑ Badenhorst, Daleen; Stanyon, Roscoe; Engstrom, Tag; Valenzuela, Nicole (2013-03-20). "A ZZ/ZW microchromosome system in the spiny softshell turtle, Apalone spinifera, reveals an intriguing sex chromosome conservation in Trionychidae". Chromosome Research. 21 (2): 137–147. doi:10.1007/s10577-013-9343-2. ISSN   0967-3849. PMID   23512312. S2CID   14434440.
  10. ↑ Jenyns, Soame (1930), "The tortoise and the turtle in Kwongtung" (PDF), The Hong Kong Naturalist, 1: 161–163
  11. ↑ Mitsukuri, Kakichi (1906), "The cultivation of marine and fresh-water animals in Japan", in Rogers, Howard Jason (ed.), Congress of arts and science: Universal exposition, St. Louis, 1904, Houghton, Mifflin and company, pp. 694–732. The Japanese variety of Pelodiscus sinensis is referred to in Mitsukuri's article under its older name, Trionyx japonicus.
  12. ↑ Zhao Huanxin, "Low price hurts turtle breeding Archived 2013-10-21 at the Wayback Machine ". China Daily 1999-06-30 (scroll to the end of the file to find that article)
  13. ↑ Zhang Jian (章剑), Chinese soft-shelled turtle value return Archived 2011-05-26 at the Wayback Machine , 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 "中国龟鳖网". Archived from the original on 2010-11-18. Retrieved 2009-12-28. )
  14. 1 2 Shi, Haitao; Parham, James F.; Fan, Zhiyong; Hong, Meiling; Yin, Feng (2008). "Evidence for the massive scale of turtle farming in China". Oryx. 42: 147–150. doi: 10.1017/S0030605308000562 (inactive 1 December 2024).{{cite journal}}: CS1 maint: DOI inactive as of December 2024 (link) Also at http://sites.google.com/site/jfparham/2008Shi.pdf
  15. ↑ "China Gobbling Up Florida Turtles" Archived 2015-05-18 at the Wayback Machine , By CRAIG PITTMAN, St. Petersburg Times. Published: Thursday, October 9, 2008
  16. ↑ Freshwater Fish and Wildlife, Rule No. 68A-25.002: General Provisions for Taking Possession and Sale of Reptiles
  17. ↑ (South Carolina) Legislative Update, June 5, 2009, Vol. 26, No. 16 (see Bill H.3121)
  18. 1 2 3 4 5 6 7 8 9 10 11 "Trionychidae". Fossilworks. Retrieved 17 December 2021.
  19. 1 2 Joyce, Walter G.; Ariel Revan; Tyler R. Lyson; Igor G. Danilov (2009). "Two New Plastomenine Softshell Turtles from the Paleocene of Montana and Wyoming" (PDF). Bulletin of the Peabody Museum of Natural History. 50 (2): 307–325. doi:10.3374/014.050.0202. S2CID   85505337.
  20. ↑ Joyce, Walter G.; Lyson, Tyler R.; Williams, Scott (2016). "New cranial material of Gilmoremys lancensis (Testudines, Trionychidae) from the Hell Creek Formation of southeastern Montana, U.S.A". Journal of Vertebrate Paleontology. 36 (6): e1225748. Bibcode:2016JVPal..36E5748J. doi:10.1080/02724634.2016.1225748. S2CID   133358179.

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