The flap-like appendages on the sides of the head and neck have been found to be highly sensitive to water movements caused by fish swimming by, which it preys upon. The mouth is extremely wide, and the snout is very long, enabling the creature to breathe while almost completely submerged. The eyes of the Matamata are very small and situated very near the snout. This tends to indicate they are of little value in capturing prey. The limbs are poorly developed.
Adults are uniformly dark brown or black.
The throat area is red, pink, or dull buff. The young have brown carapaces and plastrons. In common with the soft-shelled turtles, the nasal region of this species is elongated, enabling the nose to be used as a snorkel. The Matamata will lurk quietly for long periods in shallow water, ready to pounce on passing prey. This species inhabits stagnant pools in Brazil and the Guianas and also in parts of the Amazon River and in Trinidad.