Black Marsh Turtle

Adult black marsh turtles are usually small to medium-sized, averaging at around 17 cm (6.7 in) in length and rarely exceeding 20 cm (7.9 in). Some individuals, however, are known to grow to twice this size. The ovoid carapace (the dorsal shell) is widest just behind the middle portion, with a strongly serrated posterior margin. A prominent central ridge (known as keels) also runs through the middle of the carapace. Two lateral keels are present as well, though they are not always visible. The carapace is almost entirely black or dark brown with black radiating patterns. The plastron (the ventral shell) is not hinged and has a shallow U-shaped notch in the pair of anal scutes. The bridge (the parts connecting the abdominal and pectoral scutes of the plastron to the carapace) is approximately the same length as the rear part of the plastron (consisting of the femoral and anal scutes). Both the bridge and the plastron can be entirely black, dark brown, or yellowish with splotches or patterns of darker colors. The forelimbs are covered with large transverse scales. Both the forelimbs and the hind limbs are webbed, reflecting their largely aquatic habits. The necks of black marsh turtles are characteristically thick, forming a collar around the head when it is retracted into the shell. All of the limbs, the tail, and the neck are dark gray to black. …

Black marsh turtles can be found in southern Vietnam, Cambodia, southern Myanmar (Tenasserim), central and peninsular Thailand, eastern and western Malaysia, Singapore, and the Indonesian islands of Java, Kalimantan, and Sumatra. A specimen discovered in the Cerucuk River on Belitung Island in May 2023 is the first official record of the species on the island and represents a significant range extension beyond previously recorded populations in Sumatra to the west and Borneo to the east. Black marsh turtles live in slow-moving or stagnant warm waters with abundant vegetation – usually marshes, swamps, and ponds. As their common name implies, black marsh turtles are primarily aquatic and prefer to stay buried in soft mud when not feeding.

Black marsh turtles are predominantly carnivorous and prefer to feed underwater. They prey on insects, worms, molluscs, amphibians, crustaceans, and small fish, though they will occasionally scavenge rotting plants, fruits, or carcasses of larger animals that fall into the water. Juveniles are typically more carnivorous than adults. Black marsh turtles are shy creatures. Mostly aquatic and nocturnal, they will sometimes come out to land at night to forage or mate, and occasionally during the day to bask. Majority of the time they prefer to stay underwater, partially buried in mud in shallow water or swimming near the bottom in deeper still waters. When threatened, black marsh turtles excrete a foul-smelling secretion from their cloaca to ward off would-be predators. Their powerful jaws are also capable of inflicting wounds if handled roughly.

Life cycle. Black marsh turtles reach sexual maturity at five years. Nesting season occurs in the summer, between April and the end of June. In courtship, males will bob their heads up and down while chasing a female. It may bite the legs of the females several times before mating. Females will lay three or four clutches. Each clutch consisting usually of one or rarely two relatively large eggs, around 5 by 3 cm (2.0 by 1.2 in) and weighing 30 g (0.066 lb). The eggs are incubated for 68 to 84 days before hatching. …