Biology:Madagascan big-headed turtle
| Madagascan big-headed turtle | |
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| Photographed at Berenty Reserve | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | Testudines |
| Suborder: | Pleurodira |
| Family: | Podocnemididae |
| Genus: | Erymnochelys Baur, 1888 |
| Species: | E. madagascariensis
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| Binomial name | |
| Erymnochelys madagascariensis (Grandidier,1867)[1]
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The Madagascan big-headed turtle (Erymnochelys madagascariensis)[1] is a turtle native to the waters of permanent slow moving rivers and lakes in western Madagascar . These turtles are critically endangered and have been evaluated to be the most endangered turtle in the world by a 2018 review.[3] Due to its ancient origins and threatened status, it is ranked as #1 on the EDGE of Existence programme's list of priority reptiles.[4]
Taxonomy
It is a highly evolutionary distinctive species, the only member of the ancient family Podocnemidae found outside of South America. It diverged from its closest relative, Podocnemis, during the Late Cretaceous, about 78 million years ago, possibly following the submergence of a land bridge connecting South America and Antarctica with Madagascar.[5]
Despite Madagascar's long isolation and extensive number of endemic species, the Madagascan big-headed turtle is among the only terrestrial vertebrates whose isolation on Madagascar is thought to be due to Gondwanan vicariance during the Cretaceous; the only other extant Malagasy land vertebrates with this evolutionary history are two genera of blindsnakes (Madatyphlops and Xenotyphlops). All other Malagasy land vertebrates dispersed from the mainland to an already-isolated Madagascar from the latest Cretaceous to the present.[6]
Description
The Madagascan big-headed turtle is one of the most endangered turtles in the world, and is also included in the Turtle Conservation Funds (TCF) top 25 endangered. It has a hard dark brown shell enclosing all the soft parts of the body and, as its name indicates, a very large head. Young turtles have a soft pattern of fine black lines on their shells, but they disappear with age.[7]
Habitat
This species inhabits large areas with freshwater such as permanent slow streaming rivers, backwaters and lakes. Many of the hatching and juvenile turtles move into smaller rivers, where they can grow quickly and safely before going into deeper and larger bodies of water.
Range
It can be found in the western lowland areas of Madagascar.[8]
Threats
The main threat for this species is that they are heavily exploited for food, caught in nets, fish traps and by hooks and lines. It is also hunted for illegal export to Asia for the traditional medicinal market. Another threat is land development as it destroys its natural habitat.
Despite their vulnerability to extinction, they are commonly eaten for food and they are still commonly shipped from Madagascar to Asia to help meet the demand of Asia's traditional medicine market. A captive breeding program has also been started to prevent the species from becoming extinct. The Turtle Conservation Fund (TCF) intends to raise US$5.6 million to cover a five-year 'Global Action Plan' which includes captive breeding and reintroduction projects, trade monitoring, new rescue centers, local conservation plans, and educational programs.
References
- ↑ 1.0 1.1 1.2 Rhodin, Anders G.J.; van Dijk, Peter Paul; Inverson, John B.; Shaffer, H. Bradley (2010-12-14). "Turtles of the world, 2010 update: Annotated checklist of taxonomy, synonymy, distribution and conservation status". Chelonian Research Monographs 5: 000.136. doi:10.3854/crm.5.000.checklist.v3.2010. ISBN 978-0965354097. http://www.iucn-tftsg.org/wp-content/uploads/file/Accounts/crm_5_000_checklist_v3_2010.pdf.
- ↑ "Appendices | CITES". https://cites.org/eng/app/appendices.php.
- ↑ Gumbs, Rikki; Gray, Claudia; Wearn, Oliver; Owen, Nisha (2018). "Tetrapods on the EDGE: Overcoming data limitations to identify phylogenetic conservation priorities". PLOS ONE 13 (4): e0194680. doi:10.1371/journal.pone.0194680. PMID 29641585. PMC 5894989. Bibcode: 2018PLoSO..1394680G. http://spiral.imperial.ac.uk/bitstream/10044/1/57944/9/journal.pone.0194680.pdf.
- ↑ "Species" (in en-GB). https://www.edgeofexistence.org/species/.
- ↑ Vargas-Ramírez, Mario; Castaño-Mora, Olga V.; Fritz, Uwe (2008-12-20). "Molecular phylogeny and divergence times of ancient South American and Malagasy river turtles (Testudines: Pleurodira: Podocnemididae)" (in en). Organisms Diversity & Evolution 8 (5): 388–398. doi:10.1016/j.ode.2008.10.001. ISSN 1439-6092. https://www.sciencedirect.com/science/article/pii/S143960920800055X.
- ↑ Ali, Jason R.; Hedges, S. Blair (2023-05-04). "The colonisation of Madagascar by land‐bound vertebrates" (in en). Biological Reviews. doi:10.1111/brv.12966. ISSN 1464-7931. https://onlinelibrary.wiley.com/doi/10.1111/brv.12966.
- ↑ "Madagascar big-headed turtle videos, photos and facts - Erymnochelys madagascariensis". http://www.arkive.org/madagascar-big-headed-turtle/erymnochelys-madagascariensis/.
- ↑ "Madagascar big-headed turtle videos, photos and facts - Erymnochelys madagascariensis". http://www.arkive.org/madagascar-big-headed-turtle/erymnochelys-madagascariensis/#text=Range.
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