Fresh water turtles eat dead and sick fish, thus helping to keep their environment clean. Turtles, like all reptiles, need less oxygen than most mammals and birds, due to the fact that their bodies maintain approximately the same temperature as the surroundings. They do not have to burn oxygen to stay warm. Because of this, aquatic turtles can stay underwater for long periods of time without having to come up for air. They are als able to breathe in oxygen by absorbing it into their cloaca, or excretory chamber.
Turtles also have very small brains.
Their reflex actions are far more developed than their intelligence. The keenest sense by far is their sense of smell. They are not able to see very well, but can pick up vibrations with their whole body, even through their shell. Unlike birds, turtles do not lay eggs with hard shells. Their eggs are elastic like parchment, allowing moisture to enter.