The matamata is an enigma. This freshwater turtle from the Amazon basin spends most of its time in the water, but it is not a good swimmer. Instead, it walks along the river bottom. Its triangular head resembles the leaves of an aquatic plant called mucka-mucka (Montrichardia arborescens), helping it camouflage. The matamata can hold its breath while submerged for several hours by absorbing oxygen from the water, and its snorkel-like nose allows it to breathe while its body remains submerged. The short shell is medium brown with ridged scutes (bony plates), often covered with algae. The shell can easily be mistaken for a rock, especially in muddy waters. These turtles are solitary and rarely venture onto land.
The matamata cannot retract its head into its shell. Instead, the long neck tucks under the front edge of its shell, remaining somewhat exposed to predators. The neck and head of the matamata are covered in unusual flaps (barbels), some of which are full of nerve endings. These allow the turtle to detect disturbances in the water that might mean prey is near. Matamatas are ambush hunters that wait motionless for prey to come to them. Once in range, the matamata quickly strikes. They open their mouths and contract throat muscles to create a vacuum that draws prey in. Turtles do not have teeth, and so fish are eaten whole.
Shallow water in lakes, ponds, and slow-running creeks in the Amazon basin.
Carnivorous. Their diet includes small fishes, frogs, insects, and other aquatic invertebrates.
About 20 inches long, matamatas can weigh up to 33 pounds. Females are generally larger than males. Lifespan is estimated at 15-45 years.