The matamata is a South American turtle with a striking appearance. Its carapace, or shell, is rough and knobby, and its long neck has skin fringes, bumps and ridges. The matamata turtle’s large, flat head features a wide mouth and a long, snorkel-like snout.
One of the matamata turtle’s most prominent features, its carapace (or shell), is impressive in both size and aspect. It can grow to nearly 45 centimeters (approximately 2 feet) long and weigh 17.2 kilograms (38 pounds). That’s about the weight of an average 4-year-old child! The carapace is rough and knobby with three keels, or ridges, that run from the front to the back of the shell. The costal scutes—the scutes that run alongside those in the center of the shell—are conical with well-marked concentric growth rings.
The matamata turtle also has a large, flattened head and neck. The turtle’s small eyes are nested on the sides of the head, and at its tip is a long, tubular snout. That snout is used like a snorkel, minimizing the turtle’s movement as only the tip of the snout needs to emerge from the water during respiration. Matamatas have extremely poor eyesight, but a number of other sensory aids allow them to detect movements in the murky substrates they inhabit.
Fleshy flaps extend from the sides of their triangular head, as well as along the neck, which is covered with bumps and ridges. Those skin flaps help camouflage the turtle and contain nerves that respond to stimuli, such as the vibrations caused by the nearby movement of potential prey. Tubercles near the corners of the mouth and neck, as well as barbels on the chin, also reportedly have sensory nerves. The turtle’s ears are large and extremely sensitive to sound.
All of the matamata turtle’s digits are webbed. Its forelimbs have five claws, while its hind legs have four. The turtles legs are small with papillose skin and studded scales. Its tail is also papillose, short and pointed.
The shell and neck of a juvenile matamata turtle is a dark brown to mahogany, while the plastron (or underside of the shell) is usually a bright salmon color. As they age, the salmon color fades into yellows and browns. The throat transitions from a reddish brown to a tan or brown.
Matamata turtles exhibit some sexual dimorphism, or variation in appearance between male and female. Males have thicker tails than females, as well as concave plastrons. When the turtle’s tail is extended, the male’s vent, or anal opening, is beyond the posterior edge of the carapace. The female’s vent is under the edge of the carapace.
Despite being an aquatic species, matamatas are not well adapted for swimming in open water. They are better suited for walking the muddy beds of shallow pools of water, among leaf and plant debris. Hatchlings and juveniles can swim awkwardly, but adults rarely leave the bottom of shallow pools and streams.