Giant Asian pond turtle (Heosemys grandis)
|Also known as:||giant leaf turtle|
|Size||Length: c. 45 cm (2)|
|Weight||up to 12 kg (2)|
Classified as Vulnerable (VU) on the IUCN Red List 2007 (1), and listed on Appendix II of CITES (3).
The giant Asian pond turtle is one of the largest hard-shelled, semi-aquatic Asian turtles. The large carapace (upper shell) is brown to greyish-brown or black, with a well-defined ridge running along the centre that may be highlighted with a pale streak. The plastron (lower shell) is yellow, and in young turtles has a pattern of black lines radiating out from black blotches on each scute. The broad head is greyish-green to brown and mottled with numerous yellow, orange, or pink spots, which disappear with age. The jaws are cream to horn coloured, the snout is slightly protruding, and a shallow, v-shaped indentation on the upper jaw is flanked by a pair of tooth-like projections. Its large limbs and webbed toes are perfect adaptations for a semi-aquatic life style. Male giant Asian pond turtles can be distinguished from females by their thicker tails and the slightly inwards curve of their plastron (4).
Occurs in mainland Southeast Asia, where it has been recorded in Cambodia, Malaysia, Myanmar, Thailand and Vietnam. It most likely also occurs in Lao PDR (2).
The giant Asian pond turtle inhabits a range of freshwater habitats, including rivers, streams, lakes, swamps and marshes, from sea level up to hilly areas (2) (4). However, the giant Asian pond turtle is not restricted to water, and can also be found partially hidden under vegetation on land (4).
The biology and ecology of this huge pond turtle are poorly known. It is reported that in the wild the giant Asian pond turtle feeds largely on aquatic plants, but in captivity they have an omnivorous diet (4).
Information regarding breeding in the giant Asian pond turtle also comes from observations of individuals in captivity. Males have been seen biting at the head and neck of females, which is likely to be part of an aggressive courtship ritual that lasts up to several hours (4) (5). Following this, the male mounts the female and tightly grips the female’s shell during mating. About a month after mating, the female lays a clutch of four to six eggs, which hatch after 100 days of incubation at 27 to 28° Celsius (5). The young hatchlings have a soft area in the centre of the plastron (6)
The most significant threat that the giant Asian pond turtle faces is the prevalent and uncontrolled trade in freshwater turtles in Southeast Asia. All Heosemys species are extensively traded and are being pushed towards extinction (1) (7). In Malaysia, the giant Asian pond turtle makes up around 14 percent of the reported exports of freshwater turtles (7). The giant pond turtle is exploited for subsistence food, for the international pet trade, and to satisfy a long-standing, yet increasing demand in China for food and medicine, where turtles are believed to have significant benefits for human health. Trade in Southeast Asian turtles has grown substantially in the past 10 to 15 years due to improved economic conditions in China, Malaysia and Thailand, as well as the opening up of markets in Vietnam, Cambodia and Lao after their long isolation (8).
The giant Asian pond turtle is listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), meaning that any international trade should be carefully monitored to ensure it is compatible with the species survival (3). While this listing is likely to have benefited the turtle, illegal trade remains a significant threat. A number of conservation organisations are working to protect Asian freshwater turtles from extinction, such as the Turtle Conservation and Ecology Programme (TCEP) in Vietnam. The TCEP is involved in a range of conservation activities including research, training wildlife protection officers, and raising awareness of the plight of this group of reptiles, as well as establishing a Turtle Conservation Centre at Cuc Phuong National Park. The centre receives turtles confiscated from the illegal trade and it has been possible to reintroduce some of these turtles, such as 48 giant Asian pond turtles, back into the wild (9) (10).
For more information on the conservation of Asian freshwater turtles see:
- Asian Turtle Conservation Network:
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- Incubation: the act of incubating eggs, that is, keeping them warm so that development is possible.
- Omnivorous: feeding on both plants and animals.
- Plastron: in reptiles, the lower shell of a turtle.
- Scute: a large, bony plate or scale on the upper or lower shell of a turtle or tortoise.
IUCN Red List (July, 2014)