Siebenrockiella crassicollis (Black marsh turtle)

Siebenrockiella crassicollis, commonly known as the black marsh turtle, is a freshwater species native to Southeast Asia. It has a dark, almost black shell and is known for its secretive nature, often hiding in muddy waters and dense vegetation.

Scientific Classification

Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Testudines
Family: Geoemydidae
Genus: Siebenrockiella
Species: S. crassicollis

Common Names

• Black marsh turtle
• Asian black turtle
• Smiling terrapin

Identification

Description

The black marsh turtle has a dark brown to black carapace with a slightly domed shape and smooth texture. Its plastron is also dark, often featuring yellow markings along the seams. The head is large, with a rounded snout and a distinct “smiling” expression due to its jaw shape. The skin is blackish with some light speckling on the head and neck.

Sexual Dimorphism

Females are generally larger than males and have shorter, thicker tails. Males have a more concave plastron, which helps them during mating, while females have a flatter underside.

Native Origin and Distribution

Geographical Range

This species is found in Southeast Asia, including Thailand, Cambodia, Vietnam, Malaysia, Indonesia, and parts of Myanmar. It primarily inhabits lowland freshwater regions but has been spotted in higher elevations.

Preferred Habitat

Black marsh turtles thrive in slow-moving or stagnant freshwater habitats such as marshes, swamps, ponds, and rice paddies. They prefer areas with dense aquatic vegetation and muddy bottoms where they can burrow and hide.

Behavior

Feeding Habits

They are omnivorous, feeding on small fish, amphibians, insects, worms, snails, and plant material. They scavenge opportunistically and often hunt at night, making them nocturnal feeders.

Predators

Natural predators include large fish, crocodiles, monitor lizards, and birds of prey. Hatchlings and juveniles are especially vulnerable to predation.

Reproduction

Breeding Season

Mating typically occurs during the wet season, from May to October, when water levels are high.

Reproductive Method

Females lay 2–6 eggs per clutch in sandy or muddy banks near water bodies. Incubation lasts around 80–100 days, and hatchlings emerge with dark shells, resembling miniature adults.

Conservation

Extinction Status

Listed as Endangered on the IUCN Red List due to habitat destruction and overexploitation.

Threats

Illegal pet trade and harvesting for food and traditional medicine have drastically reduced wild populations. Wetland drainage for agriculture and urban expansion further threaten their habitat.

Conservation Measures

Several breeding programs exist, and protected areas have been established in some regions. Efforts are being made to regulate the pet trade and enforce stricter conservation laws.

Economic Importance

This species is often captured for food, traditional medicine, and the pet trade. Some local communities use them in religious ceremonies. However, their declining numbers have raised concerns about sustainability.

Interesting Facts

• The black marsh turtle gets its “smiling terrapin” nickname due to the natural curve of its mouth, making it look like it is always grinning.
• It is highly aquatic and rarely leaves the water, except for basking or nesting.
• When threatened, it releases a strong musky odor to deter predators.
• Unlike many turtles, it does not rely heavily on basking and can remain submerged for long periods.