The mata mata, mata-mata, or matamata (Chelus fimbriata) is a freshwater turtle found in South America, primarily in the Amazon and Orinoco basins. It is the only extant species in the genus Chelus.The mata mata is a large, sedentary turtle with a large, triangular, flattened head characterized with many tubercles and flaps of skin, and a "horn" on its long and tubular snout. Three barbels occur on the chin and four additional filamentous barbels at the upper jaw, which is neither hooked nor notched.The mata mata's brown or black, oblong carapace can measure up to 45 cm (18 in) at adult age. The full adult weight is 15 kg (33 lb). The mata mata's plastron is reduced, narrowed, hingeless, shortened towards the front, and deeply notched at the rear with narrow bridges. These may be meant to allow the turtle to resemble a piece of bark, camouflaging it from possible predators.The plastron and bridges are cream to yellow or brown.The mata mata inhabits slow moving, blackwater streams, stagnant pools, marshes, and swamps ranging into northern Bolivia, eastern Peru, Ecuador, eastern Colombia, Venezuela, the Guianas, and northern and central Brazil. The mata mata is strictly an aquatic species but it prefers standing in shallow water where its snout can reach the surface to breathe.The mata mata is carnivorous, feeding exclusively upon aquatic invertebrates and fish.