Mata Mata - Their flat heads, jagged skin and shells make them look like rocks or bark in the water. Even though they live in fresh water, these guys are lousy swimmers. They walk along the bottom and prefer to stay in shallow depths.
Esophagus of Leatherback turtles showing backward pointing spikes. Adult leatherback sea turtles subsist almost entirely on jellyfish. Jellyfish are pretty slippery, you see, and the razor-sharp rows of papillae prevent them from slipping out of the turtle's mouth.
The best freshwater turtle site I've found yet. Definitely the place to go for pet aquatic turtle information. Aquatic turtles are often purchased with little to no advance research, and pet stores lie flagrantly about their care. They often grow much larger, and require far more equipment, than people remotely imagine. As a result, these are the reptiles that wind up in rescues the most frequently. If you want a RES, consider adopting.