English name: Black Marsh Turtle (aka “Black Mud Turtle”, “Black Terrapin”, or “Smiling Terrapin”)
Scientific name: Siebenrockiella crassicollis
Thai name: Tao Dam
Description: Shell is up to 30cm long. A small turtle species with a keeled shell. Shell and body are black, sometimes with brown streaks. Head is large and black and sometimes has round white spots, which may be distinct or faded. The distinctly upturned mouth has given it the alternative name, “Smiling Terrapin”.
Similar Species: Malayan Snail-eating Turtle has light stripes on the head rather than pale spots.
Southeast Asian Box Turtle has a higher shell and light stripes on the head.
Red-eared Slider has red and yellow markings on its head.
Giant Asian Pond Turtle has a higher shell and is much larger.
Habitat: Found in marshes, swamps, ponds, and other shallow, slow-moving water bodies with dense vegetation. Spends most of the day at the muddy water bottoms, only surfacing occasionally. Will sometimes come onto the banks at night to forage.
Contribution to the ecosystem: Helps clean up discarded food and rotting plants and animals, as well as controlling snail, insect, worm, crustacean, and shellfish populations. Provides food for water monitors and wading birds.
Danger to humans: Is not dangerous to humans. When threatened, it will release a foul-smelling musk.
These turtles have been found to have high levels of mercury in their flesh, due to their long lives and the high levels of pollution in the water bodies in which they are found. They should not be eaten.
Conservation status and threats: The Black Marsh Turtle is classified as “Vulnerable” on the IUCN Red List and is listed in CITES Appendix II. In Cambodia and Vietnam it is considered Endangered. The greatest threats to this turtle are hunting and capture for the pet trade and “merit-making”, and in Thailand it is also threatened by habitat loss. Besides their meat, they are also hunted for their shells, which are used in traditional Chinese medicine.
Interesting facts: Black Marsh Turtles are often released into temple ponds and other artificial habitats. Some Thai people believe that the Black Marsh Turtle carries the souls of people who died while trying to rescue others from drowning, and thus they are treated as sacred.
The only time I have seen this turtle was while waiting for a bus at night in downtown Bangkok. While I was waiting I took a look at the nearby canal, and was surprised to see three Black Marsh Turtles prowling the edge of the water. They swam alongside the concrete banks, occasionally climbing up onto land to reach discarded food. I had my camera with me and was able to take the photos shown in this species account. Though I had been to that canal many times before, I had never seen a Black Marsh Turtle there. It’s a good lesson for herping in the city – always keep a look out, because you never know when your one chance to see a particular herp might come.
ARKive: Black Marsh Turtle
Asian Turtle Conservation Network: Siebenrockiella crassicollis
IUCN Red List: Siebenrockiella crassicollis
Wikipedia: Black Marsh Turtle
Buddhist Merit-making Turtle Release Checklist
Thailand Office of Environmental Planning and Policy: A Checklist of Amphibians and Reptiles in Thailand
A Photographic Guide to Snakes and Other Reptiles of Peninsular Malaysia, Singapore and Thailand
A Field Guide to the Reptiles of South-East Asia
The Turtles of Thailand