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Asian giant softshell turtle
Species of freshwater turtle

The Asian giant softshell turtle (Pelochelys cantorii), 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.

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Taxonomy

P. cantorii is not found in New Guinea, while the two other members of the genus Pelochelys, P. bibroni and P. signifera are both restricted to New Guinea.4 P. cantorii is relatively unstudied, and the current species may actually be composed of several taxa.5 One study from 19956 showed that what was once thought to be P. cantorii in New Guinea was actually P. bibroni, and the earlier studies78 of P. cantorii only described populations farther to the west. The classification of P. cantorii is Family: Trionychidae, Order: Testudines. A genome study revealed that several genes related to tumor resistance, growth, and aging were more active in P. cantorii. The genes found were VWA5A, ABCG2, A2M, and IGSF1.They are related to tumor resistance, growth, and aging. P. cantorii fits into turtle evolution because P. cantorii became separate from its closest turtle relatives about 59 million years ago. Turtles split from the common ancestor of birds and crocodiles around 256 million years ago.

The populations of Asian giant softshell turtles in the Philippines "may be distinct" based on genetic analysis, implying the possibility of unique genetic traits in this population. More research is needed to confirm if the critically-endangered Philippine population is a distinct species.9

Description

The Asian giant softshell turtle has a broad head, and small eyes close to the tip of its snout. The carapace is smooth and olive-colored. Juveniles may have dark-spotted carapaces and heads, with yellow around the carapace.10

Despite reports that it can grow up to 1.8 metres (5.9 ft) in length and is the world's largest extant freshwater turtle, this maximum size and title is murky at best.1112 Apparently the largest specimen carapace length, 129 cm (51 in), known is considered suspect and the heaviest specimen known (weighing approximately 250 kg (550 lb) was actually a misidentified Yangtze giant softshell turtle.1314 A more realistic range of carapace length for this species is reportedly 70 to 100 cm (28 to 39 in) and it is one of about a half-dozen giant softshell turtles from three genera that reach exceptionally large sizes, i.e. in excess of 100 kg (220 lb) in mass.15

Behavior and reproduction

P. cantorii is an ambush predator and primarily carnivorous, feeding on crustaceans, mollusks and fish (although some aquatic plants may also be eaten).16 The turtle spends 95% of its life buried and motionless, with only its eyes and mouth protruding from the sand. It surfaces only twice a day to take a breath, and lays 20–28 eggs sized around 3.0 to 3.6 centimetres (1.2 to 1.4 in) in diameter in February or March on riverbanks.171819

Morphological variation

Morphological differences in neural bone count have been noted between specimens of P. cantori found in the Philippines and specimens found in mainland Asia.20

Etymology

The specific name, cantorii, is in honor of Danish zoologist Theodore Edward Cantor.21 Additionally, they are named for their softshells because they have soft, leathery shells that are completely devoid of scales.

Geographic range and habitat

The species P. cantorii is primarily found in inland, slow-moving, freshwater rivers and streams. Some evidence indicates that its range extends to coastal areas, as well.22 It occurs in eastern and southern India, Bangladesh, Burma, Thailand, Malaysia, Laos, Cambodia, Vietnam, eastern and southern China, the Philippines (Luzon and Mindanao), and Indonesia (Kalimantan, Java, and Sumatra).23

Conservation

The Asian giant softshell turtle is classified as a Critically Endangered by the IUCN and has been forced out through habitat destruction, disappearing from much of its range.24 Prior to 2007, it was last seen in Cambodia in 2003. A 2007 survey of one area of the Mekong River in Cambodia found the turtle in abundance along a 48 kilometres (30 mi) stretch of the river.2526

In the Philippines, a juvenile Cantor's turtle known as "cagot" appeared and was captured by a fisherman along the Addalam River, Cabarroguis, Quirino, Isabela. In 2001, this turtle was sent to Chicago and its identity confirmed.27 The geographic range of the turtle was initially murky in the Philippines, but recent studies have confirmed their range in at least two islands, Luzon and Mindanao. Unfortunately, the invasive Chinese softshell turtle has become present in these two islands due to illegal introductions from mainland China. The Department of Environment and Natural Resources lists the Asian giant softshell turtle as a protected species and its trade is illegal under Philippine law, while it allows, through specific legal processes, the culling and catching of the invasive Chinese softshell turtle for import purposes, as to reduce the number of the invasive species, especially in areas where the indigenous Asian giant softshell turtle is present. Unfortunately, not all locals are aware of the difference between the two species which look similar, and this has led to the illegal catching of Asian giant softshell turtles in some instances. The department has yet to resolve this key issue in the conservation of Asian giant softshell turtles in the Philippines, where genetic studies have confirmed that the Philippine populations have distinct features from other populations in Asia.2829303132

The reptile has been evaluated as an EDGE species by the Zoological Society of London.33

Further reading

  • Das, Indraneil (2002). A Photographic Guide to Snakes and other Reptiles of India. Sanibel Island, Florida: Ralph Curtis Books. 144 pp. ISBN 0-88359-056-5. (Pelochelys cantorii, p. 139).
  • Das, Indraneil; Lakim, Maklarin (December 2006). "On the Distribution of Pelochelys cantorii on Borneo" (PDF). Chelonian Conservation and Biology. 5 (2): 323–325. doi:10.2744/1071-8443(2006)5[323:OTDOPC]2.0.CO;2. S2CID 85822468.
  • McCord, William P.; Joseph-Ouni, Mehdi (2003). "Flapshell and Giant Asian Softshell Turtles". Reptilia. 26: 59–64.
  • Webb, Robert G (2002). "Observations on the Giant Softshell Turtle, Pelochelys cantorii, with description of a new species". Hamadryad. 27 (1): 99–107.
Wikispecies has information related to Pelochelys cantorii.

Media related to Pelochelys cantorii at Wikimedia Commons

References

  1. Choudhury, B.C.; Das, I.; Horne, B.D.; Li, P.; McCormack, T.; Praschag, P.; Rao, D.-Q.; Wang, L. (2021). "Pelochelys cantorii ". IUCN Red List of Threatened Species. 2021: e.T135458600A1076984. doi:10.2305/IUCN.UK.2021-2.RLTS.T135458600A1076984.en. Retrieved 19 November 2021. https://species.wikimedia.org/wiki/Binod_Chandra_Choudhury ↩

  2. Rhodin, Anders G.J.; Iverson, John B.; Roger, Bour; Fritz, Uwe; Georges, Arthur; Shaffer, H. Bradley; van Dijk, Peter Paul (August 3, 2017). "Turtles of the world, 2017 update: Annotated checklist and atlas of taxonomy, synonymy, distribution, and conservation status (8th Ed.)" (PDF). Chelonian Research Monographs. 7. ISBN 978-1-5323-5026-9. Retrieved October 4, 2019. 978-1-5323-5026-9 ↩

  3. Rhodin, Anders G.J.; Iverson, John B.; Roger, Bour; Fritz, Uwe; Georges, Arthur; Shaffer, H. Bradley; van Dijk, Peter Paul (August 3, 2017). "Turtles of the world, 2017 update: Annotated checklist and atlas of taxonomy, synonymy, distribution, and conservation status (8th Ed.)" (PDF). Chelonian Research Monographs. 7. ISBN 978-1-5323-5026-9. Retrieved October 4, 2019. 978-1-5323-5026-9 ↩

  4. Rhodin, Anders G.J.; Iverson, John B.; Roger, Bour; Fritz, Uwe; Georges, Arthur; Shaffer, H. Bradley; van Dijk, Peter Paul (August 3, 2017). "Turtles of the world, 2017 update: Annotated checklist and atlas of taxonomy, synonymy, distribution, and conservation status (8th Ed.)" (PDF). Chelonian Research Monographs. 7. ISBN 978-1-5323-5026-9. Retrieved October 4, 2019. 978-1-5323-5026-9 ↩

  5. Ernst, C.H.; Altenburg, R.G.M.; Barbour, R.W. (1998). Turtles of the world [CD-ROM]. https://species.wikimedia.org/wiki/Carl_H._Ernst ↩

  6. Webb, R.G. (1995). "Redescription and neotype designation of Pelochelys bibroni from southern New Guinea (Testudines: Trionychidae)". Chelonian Conservation and Biology. 1 (4): 301–310. /wiki/Robert_G._Webb ↩

  7. Gray, J.E. (1864). "Revision of the species of Trionychidae found in Asia and Africa, with the descriptions of some new species". Proceedings of the Zoological Society of London. 1864: 76–98. /wiki/John_Edward_Gray ↩

  8. Boulenger, G.A. (1891). "XXXI.—On the occurrence of Pelochelys in China". Journal of Natural History. 7 (39): 283–284. doi:10.1080/00222939109460609. /wiki/George_Albert_Boulenger ↩

  9. https://iucn-tftsg.org/wp-content/uploads/file/Accounts/crm_5_011_cantorii_v1_2008.pdf https://iucn-tftsg.org/wp-content/uploads/file/Accounts/crm_5_011_cantorii_v1_2008.pdf ↩

  10. Ernst, C.H.; Altenburg, R.G.M.; Barbour, R.W. (1998). Turtles of the world [CD-ROM]. https://species.wikimedia.org/wiki/Carl_H._Ernst ↩

  11. "Rare Soft Shell Turtle, Nesting Ground Found in Cambodia". ScienceDaily. 19 May 2007. https://www.sciencedaily.com/releases/2007/05/070517074755.htm ↩

  12. Mydans, Seth (18 May 2007). "How to Survive in Cambodia: For a Turtle, Beneath Sand". New York Times. https://www.nytimes.com/2007/05/18/world/asia/18turtles.html ↩

  13. De Rooij, N. (1915). The Reptiles of the Indo-Australian Archipelago. A. Asher. /wiki/Nelly_de_Rooij ↩

  14. Pritchard, P.C. (2005). "Survival status and prospects for Rafetus swinhoei (Chelonia: Trionychidae)". 2005 Turtle Survival Alliance Annual Conference Proceedings: 19–22. /wiki/Peter_Pritchard ↩

  15. Das, I. (2010). "Pelochelys cantorii Gray 1864 – Asian Giant Softshell Turtle". In Iverson, J.B.; Mittermeier, R.A. (eds.). Conservation Biology of Freshwater Turtles and Tortoises: A Compilation Project of the IUCN/SSC Tortoise and Freshwater Turtle Specialist Group. Chelonian Research Monographs. Vol. 5. /wiki/Russell_Mittermeier ↩

  16. Ernst, C.H.; Altenburg, R.G.M.; Barbour, R.W. (1998). Turtles of the world [CD-ROM]. https://species.wikimedia.org/wiki/Carl_H._Ernst ↩

  17. Ernst, C.H.; Altenburg, R.G.M.; Barbour, R.W. (1998). Turtles of the world [CD-ROM]. https://species.wikimedia.org/wiki/Carl_H._Ernst ↩

  18. Mydans, Seth (18 May 2007). "How to Survive in Cambodia: For a Turtle, Beneath Sand". New York Times. https://www.nytimes.com/2007/05/18/world/asia/18turtles.html ↩

  19. Das, I. (1985). Indian Turtles, a Field Guide. Calcutta: World Wildlife Fund--India (Eastern Region). ↩

  20. Brown, Rafe M.; Siler, Cameron D.; Oliveros, Carl H.; Welton, Luke J.; Rock, Ashley; Swab, John; Van Weerd, Merlijn; van Beijnen, Jonah; Jose, Edgar; Rodriguez, Dominic; Jose, Edmund; Diesmos, Arvin C. (2013). "The amphibians and reptiles of Luzon Island, Philippines, VIII: the herpetofauna of Cagayan and Isabela Provinces, northern Sierra Madre Mountain Range". ZooKeys (266): 1–120. Bibcode:2013ZooK..266....1B. doi:10.3897/zookeys.266.3982. PMC 3591760. PMID 23653519. https://species.wikimedia.org/wiki/Rafe_Marion_Brown ↩

  21. Beolens, Bo; Watkins, Michael; Grayson, Michael (2011). The Eponym Dictionary of Reptiles. Baltimore: Johns Hopkins University Press. p. 47. ISBN 978-1-4214-0135-5. 978-1-4214-0135-5 ↩

  22. Ernst, C.H.; Altenburg, R.G.M.; Barbour, R.W. (1998). Turtles of the world [CD-ROM]. https://species.wikimedia.org/wiki/Carl_H._Ernst ↩

  23. Rhodin, Anders G.J.; Iverson, John B.; Roger, Bour; Fritz, Uwe; Georges, Arthur; Shaffer, H. Bradley; van Dijk, Peter Paul (August 3, 2017). "Turtles of the world, 2017 update: Annotated checklist and atlas of taxonomy, synonymy, distribution, and conservation status (8th Ed.)" (PDF). Chelonian Research Monographs. 7. ISBN 978-1-5323-5026-9. Retrieved October 4, 2019. 978-1-5323-5026-9 ↩

  24. "IUCN Red List of Threatened Species: Pelochelys cantorii". 30 June 2000. https://www.iucnredlist.org/species/16502/97400946 ↩

  25. Mydans, Seth (18 May 2007). "How to Survive in Cambodia: For a Turtle, Beneath Sand". New York Times. https://www.nytimes.com/2007/05/18/world/asia/18turtles.html ↩

  26. Munthit, K. (16 May 2007). "Rare Turtle's New Chance". Associated Press. ↩

  27. Taguinod, Floro C. (8 July 2008). "After seven years, rare soft-shelled turtle resurfaces in Quirino Province". GMA News Online. http://www.gmanews.tv/story/105818/After-seven-years-rare-soft-shelled-turtle-resurfaces-in-Quirino-Province ↩

  28. https://www.livescience.com/animals/turtles/cantors-giant-softshell-turtle-the-frog-faced-predator-that-spends-95-percent-of-its-time-completely-motionless https://www.livescience.com/animals/turtles/cantors-giant-softshell-turtle-the-frog-faced-predator-that-spends-95-percent-of-its-time-completely-motionless ↩

  29. https://india.mongabay.com/2020/01/building-community-networks-to-save-a-rare-turtle-from-extinction/ https://india.mongabay.com/2020/01/building-community-networks-to-save-a-rare-turtle-from-extinction/ ↩

  30. https://asianews.network/another-invasive-chinese-softshell-turtle-found-in-philippines/ https://asianews.network/another-invasive-chinese-softshell-turtle-found-in-philippines/ ↩

  31. https://www.philstar.com/nation/2013/04/01/925401/only-chinese-softshell-turtles-can-be-collected-wild https://www.philstar.com/nation/2013/04/01/925401/only-chinese-softshell-turtles-can-be-collected-wild ↩

  32. https://www.pna.gov.ph/articles/1223988 https://www.pna.gov.ph/articles/1223988 ↩

  33. "Cantor's Giant Softshell". http://www.edgeofexistence.org/species/cantors-giant-softshell/ ↩