Southern River Terrapin

A large river turtle with an average carapace length of 625 mm, and an average body weight of 38kg with a big shell proportionate to its large size. The high-arched shell is rife with buttresses which provide structural support and protect its vital organs. The shell is responsible for a quarter of the terrapin's body weight, consisting of a carapace with wide vertebral scutes and an anteriorly truncate plastron that is relatively shorter in length (than the carapace). This highly aquatic turtle has an increased shell strength due to complete ankylosis at maturity. Bones of the carapace are fused together as one to prevent the shell from splitting further if it is crushed. Female Southern river terrapins are known for typically being larger than males and have an earlier sexual maturity. In addition to difference in body size, adult males can be identified by their more extensive tail which is longer length and is thicker. The shells of hatchlings have serrated edges of the marginal scutes, spines running down the middle of the carapace, and a vertebral keel . As the hatchlings mature, the vertebral keel, spines, and serrations disappear with age. Hatchlings from the west coast of Malaysia average somewhat smaller than those from the east coast. Morphological traits displayed in the southern river terrapin vary by geographic location. …

Batagur affinis occupies the western coast of Malaysia, western coast of Indonesia, and the southern region of Thailand on the western Malaysian Peninsula.

Fossil record. Archeological evidence of the Southern river terrapin has been discovered in the Bang Pakaong River of southeast Thailand, suggesting that B. affinis has historically inhabited major rivers that converge into southern part of the China Sea.

Wild terrapins are omnivorous. Their diet consists of vegetation, fruits, and mollusks. Their serrated beaks allow them to consume various types of plants including mangrove apple, sedges, screw palm apple, colocasia, and water hyacinth. In addition, they also ingest certain types of vine plants, grasses and fruits such as wild mangosteen and Malay apple.

The Southern River Terrapin derives its common name from its native range of Peninsular Malaysia, located in the southern half of Malaysia. Locals in Malaysia colloquially refer to the species as "tuntung" due to repetitive sounds made from the terrapin's plastron packing sand during nest construction.