Chinese softshell turtle

The Chinese softshell turtle[1] (Pelodiscus sinensis) is a species of softshell turtle that is endemic to China (Inner Mongolia to Hainan), 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.[3]

Not to be confused with northern Chinese softshell turtle or lesser Chinese softshell turtle.

Chinese softshell turtle
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Testudines
Suborder: Cryptodira
Family: Trionychidae
Genus: Pelodiscus
Species:
P. sinensis
Binomial name
Pelodiscus sinensis
(Wiegmann, 1835)[1]
Synonyms

See text

Populations native to Northeast China, Russia, Korea and Japan were formerly included in this species, but are now regarded as separate as the northern Chinese softshell turtle (P. maackii). Furthermore, localized populations in Guangxi and Hunan (where the Chinese softshell turtle also is present), as well as Vietnam, are recognized as the lesser Chinese softshell turtle (P. parviformis) and Hunan softshell turtle (P. axenaria).[3]

The Chinese softshell turtle is a vulnerable species,[3] threatened by habitat loss and collection for food such as turtle soup. Millions are now farmed, especially in China, to support the food industry,[4] and it is the world's most economically important turtle.[5]

Description

Females of the Chinese softshell turtle can reach up to 33 cm (13 in) in carapace length, while the smaller males reach 27 cm (11 in), but however have longer tails than the females.[6] Maturity is reached at a carapace length of 18–19 cm (7–7.5 in).[6] It has webbed feet for swimming. They are called "softshell" because their carapace lacks horny scutes (scales). 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. The light and flexible shell of these turtles allows them to move more easily in open water, or in muddy lake bottoms.[7]

The carapace of these turtles is olive in color and may have dark blotches. The plastron is orange-red, and may also have large dark blotches. The limbs and head are olive dorsally with the forelimbs lighter and the hind-limbs orange-red ventrally. There are dark flecks on the head and dark lines that radiate from the eyes. The throat is mottled and there may be small, dark bars on the lips. A pair of dark blotches is found in front of the tail as well as a black band on the posterior side of each thigh.[8]

Distribution and habitat
Pelodiscus sinensis

Distribution
Taxidermied Chinese softshell turtle at Philippine National Museum

The Chinese softshell turtle is endemic to China, where it is found in Anhui, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Hainan, Hebei, Henan, Hong Kong, Hubei, Hunan, Inner Mongolia (Nei Mongol), Jiangsu, Jiangxi, Shaanxi, Shandong, Shanxi, Sichuan, Yunnan and Zhejiang Provinces, as well as Taiwan.[3]

Populations native to Northeast China, Russia, Korea and Japan were formerly included in this species, but are now regarded as separate as the northern Chinese softshell turtle (P. maackii). Furthermore, localized populations in Guangxi and Hunan (where the Chinese softshell turtle also is present), as well as Vietnam, are recognized as the lesser Chinese softshell turtle (P. parviformis) and Hunan softshell turtle (P. axenaria).[3]

It is difficult to determine its exact native range of the Chinese softshell turtle due to the long tradition of use as a food and herbal medicinal,[9] and subsequent spread by migrating people.[8] Outside their native China, escapees have been recorded in a wide range of countries and some of these have becomes established as introduced populations. Among the non-native locations in Asia are the Bonin Islands, Honshu, Kyushu, Ryukyu Archipelago and Shikoku in Japan; South Korea; Laos; Vietnam; Thailand; Singapore; Bohol, Cebu, Leyte, Luzon, Mindanao, Mindoro and Panay in the Philippines; East and Peninsular Malaysia; Kalimantan, Sumatra and West Timor in Indonesia; East Timor; and Iran.[3] Outside Asia, locations include Pará in Brazil; Spain; and Guam, Northern Mariana Islands and Oahu (Hawaii) in the United States.[3][10]

Habitat

Chinese softshell turtles live in fresh and brackish water.[11][12] In China these turtles are found in rivers, lakes, ponds, canals and creeks with slow currents, and in Hawaii they can be found in marshes and drainage ditches.[8]

Ecology and behavior

Diet

These turtles are predominantly carnivorous and the remains of fish, crustaceans, mollusks, insects, and seeds of marsh plants have been found in their stomachs.[8]

Movement

With their long snout and tubelike nostrils, these turtles can "snorkel" in shallow water.[13] When resting, they lie at the bottom, buried in sand or mud, lifting their head to breathe or snatch at prey. Their basking habit is not well developed.[8]

Chinese softshell turtles often submerge their heads in water.[13] This is because they carry a gene which produces a protein that allows them to secrete urea from their mouths. This adaptation helps them survive in brackish water by making it possible for them to excrete urea without drinking too much salty water. Rather than eliminating urea by urinating through their cloaca as most turtles do, which involves significant water loss, they simply rinse their mouths in the water.[12]

When provoked, certain populations of these turtles are capable of excreting a foul smelling fluid from pores on the anterior edge of their shells.[14]

Life cycle

These turtles reach sexual maturity sometime between 4 and 6 years of age. They mate at the surface or under water. A male will hold the female's carapace with its forelimbs and may bite at her head, neck, and limbs. Females may retain sperm for almost a year after copulation.[8]

The females lay 8–30 eggs in a clutch and may lay from 2 to 5 clutches each year. The eggs are laid in a nest that is about 76–102 mm (3–4 in) across at the entrance. Eggs are spherical and average about 20 mm (0.79 in) in diameter. After an incubation period of about 60 days, which may be longer or shorter depending upon temperature, the eggs hatch. Average hatchling carapace length is about 25 mm (1 in) and width is also about 25 mm (1 in).[8] Sex of the hatchlings is not determined by incubation temperature.[14]

Conservation

Wild populations are listed as vulnerable on the IUCN Red List.[2]

Relations with humans

The Chinese softshell turtle is the most commonly raised species in China's turtle farms.[11][15] According to the data obtained from 684 Chinese turtle farms, they sold over 91 million turtles of this species every year; considering that these farms represented less than half of the 1,499 registered turtle farms in China, the nationwide total could be over twice as high.[4] These turtles are considered a delicacy in many parts of Asia.[13] Turtle soup is made from this species. In Japan, they may be stewed with hōtō noodles and served as a winter delicacy. Many Koreans, even today, generally have a taboo against eating turtles which has origins in native Korean shamanism.

These turtles can be injured if they are dropped or hit, and are susceptible to shell fungus. Within Europe, the turtle is a popular pet, particularly in countries such as Italy and the Czech Republic. Captives of this species will eat canned and fresh fish, canned dog food, raw beef, mice, frogs, and chicken. However, in captivity they do not usually eat turtle feed.[8] They can deliver a painful bite if provoked, but will usually let go after a while.

Synonyms

Numerous synonyms have been used for this species:[16]

  • Testudo rostrata Thunberg, 1787 (nomen suppressum)
  • Testudo striata Suckow, 1798
  • Testudo semimembranacea Hermann, 1804 (nomen suppressum et rejectum)
  • Emydes rostrata – Brongniart, 1805
  • Trionyx (Aspidonectes) sinensis Wiegmann, 1834 (nomen conservandum)
  • Trionyx japonicus – Temminck & Schlegel, 1835
  • Trionyx tuberculatus Cantor, 1842
  • Pelodiscus sinensis – Fitzinger, 1843
  • Tyrse perocellata Gray, 1844
  • Trionyx perocellatus – Gray, 1856
  • Trionyx schlegelii Brandt, 1857
  • Potamochelys perocellatus – Gray, 1864
  • Potamochelys tuberculatus – Gray, 1864
  • Landemania irrorata Gray, 1869
  • Landemania perocellata – Gray, 1869
  • Trionyx peroculatus Günther, 1869 (ex errore)
  • Gymnopus perocellatus – David, 1872
  • Gymnopus simonii David, 1875 (nomen nudum)
  • Ceramopelta latirostris Heude, 1880
  • Cinctisternum bicinctum Heude, 1880
  • Coelognathus novemcostatus Heude, 1880
  • Coptopelta septemcostata Heude, 1880
  • Gomphopelta officinae Heude, 1880
  • Psilognathus laevis Heude, 1880
  • Temnognathus mordax Heude, 1880
  • Trionyx sinensis newtoni Bethencourt-Ferreira, 1897
  • Tortisternum novemcostatum Heude, 1880
  • Temnognanthus mordax – Boulenger, 1889
  • Tyrse sinensis – Hay, 1904
  • Amyda japonica – Stejneger, 1907
  • Amyda schlegelii – Stejneger, 1907
  • Amyda sinensis – Stejneger, 1907
  • Amyda tuberculata – Schmidt, 1927
  • Trionyx sinensis sinensis – Smith, 1931
  • Trionyx sinensis tuberculatus – Smith, 1931
  • Amyda schlegelii haseri Pavlov, 1932
  • Amyda schlegelii licenti Pavlov, 1932
  • Amyda sinensis sinensis – Mertens, Müller & Rust, 1934
  • Amyda sinensis tuberculata – Mertens, Müller & Rust, 1934
  • Trionyx schlegeli Chkhikvadze, 1987 (ex errore)
  • Trionix sinensis – Richard, 1999
  • Pelodiscus sinensis sinensis – Ferri, 2002
  • Pelodiscus sinensis tuberculatus – Ferri, 2002
  • Pelodiscus sinensis japonicus – Joseph-Ouni, 2004

Genetics

The genome of Pelodiscus sinensis was sequenced in 2013 to examine the development and evolution of the softshell turtle body plan.[17]

References
  1. Rhodin 2010, p. 000.128
  2. Asian Turtle Trade Working Group (2000). "Pelodiscus sinensis". IUCN Red List of Threatened Species. 2000: e.T39620A97401140. doi:10.2305/IUCN.UK.2000.RLTS.T39620A10251914.en.{{cite iucn}}: error: |doi= / |page= mismatch (help)
  3. Rhodin, A.G.J., Iverson, J.B., Bour, R. Fritz, U., Georges, A., Shaffer, H.B., and van Dijk, P.P. (Turtle Taxonomy Working Group) (2017). Rhodin, A.G.J.; Iverson, J.B.; van Dijk, P.P.; et al. (eds.). Turtles of the World: Annotated Checklist and Atlas of Taxonomy, Synonymy, Distribution, and Conservation Status. Chelonian Research Monographs. Conservation Biology of Freshwater Turtles and Tortoises: A Compilation Project of the IUCN/SSC Tortoise and Freshwater Turtle Specialist Group. 7 (8 ed.). pp. 1–292. doi:10.3854/crm.7.checklist.atlas.v8.2017. ISBN 9781532350269. S2CID 89826255.CS1 maint: uses authors parameter (link)
  4. Shi, Haitao; Parham, James F; Fan, Zhiyong; Hong, Meiling; Yin, Feng (2008-01-01), "Evidence for the massive scale of turtle farming in China hi", Oryx, Cambridge University Press, 42, pp. 147–150, doi:10.1017/S0030605308000562
  5. Fritz, U., Gong, S., Auer, M., Kuchling, G., Schneeweiß, N., & Hundsdörfer, A. K. (2010). "The world's economically most important chelonians represent a diverse species complex (Testudines: Trionychidae: Pelodiscus)". Organisms Diversity & Evolution. 10 (3): 227–242. doi:10.1007/s13127-010-0007-1. S2CID 46472936.CS1 maint: uses authors parameter (link)
  6. Ernst, C.H.; J.E. Lovich (2009). Turtles of the United States and Canada (2 ed.). pp. 639, 641. ISBN 978-0-8018-9121-2.
  7. Obst, Fritz Jurgen (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.
  8. C.H. Ernst, R.G.M. Altenburg & R.W. Barbour - Turtles of the World - Pelodiscus sinensis Archived 2011-06-08 at the Wayback Machine
  9. Louis A. Somma. 2009. Pelodiscus sinensis. USGS Nonindigenous Aquatic Species Database, Gainesville, FL. Archived 2009-05-11 at the Wayback Machine Revision Date: 6/29/2004 Accessed: 15/05/2009
  10. Brock, V. E. (1947). "The establishment of Trionyx sinensis in Hawaii". Copeia. 1947 (2): 142. doi:10.2307/1438656. JSTOR 1438656.
  11. Trionyx sinensis, Food and Agriculture Organization of the United Nations, Fisheries and Aquaculture Department, retrieved 5 September 2016
  12. Kaufman, Rachel (12 October 2012). "Turtles Urinate Via Their Mouths—A First". National Geographic. Retrieved 14 October 2012.
  13. Davies, Ella. "Chinese turtle passes waste urea through its mouth". BBC Nature. Retrieved 19 October 2012.
  14. Bonin, Frank (2006). Turtles of the World. Baltimore, Maryland: The Johns Hopkins Press. pp. 146–147.
  15. Dharmananda, Subhuti, Endangered species issues affecting turtles and tortoises in Chinese medicine, Institute for Traditional Medicine, Portland, Oregon, retrieved 5 September 2016
  16. Fritz, Uwe; Havaš, Peter (2007). "Checklist of Chelonians of the World" (PDF). Vertebrate Zoology. 57 (2): 319–320. ISSN 1864-5755. Archived from the original (PDF) on 2010-12-17. Retrieved 29 May 2012.
  17. Wang Z.; Pascual-Anaya J.; Zadissa A.; et al. (2013). "The draft genomes of the soft-shell turtle and green sea turtle yield insights into the development and evolution of the turtle-specific body plan". Nature Genetics. 45 (6): 701–706. doi:10.1038/ng.2615. PMC 4000948. PMID 23624526.

Bibliography
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