This is one seriously cool turtle. It is a monotypic genus, which means that it is the only species in the genus. They live in the Amazon river system in South America and hang out in warm shallow muddy water with lots of vegetative debris. The shell and skin are excellent camouflage in this habitat, including how the head (with fringes of extra skin with sensitive nerves), looks like mucka mucka leaves (a common aquatic plant). The snout is a long thin snorkel like tube that is raised to the surface to breathe.
Mata matas either ambush or slowly stalk their prey. When suitable prey is within reach, the head shoots forward and the floor of the mouth lowers. Just before the mouth reaches the prey, the mouth opens, creating a vacuum, and prey and water rush into the mouth (which is called the buccal cavity). The mouth then shuts, but not quite all the way, the floor of the mouth rises, pushing most of the water out, and the prey is swallowed. This happens so fast, that you can barely see it. Check it out!