Mud Turtles
The larger species, or large adults of some species, tend to become aggressive and dangerous as they grow older, and many times a finger is mistaken for a morsel of food. Avoid the aforementioned turtles if your interest in these hard-shelled friends is new.
These are some turtles, of course, that can be handled without fear of biting or scratching. Any of the smaller species of sliders can make acceptable additions to your collection. Below is a list of those turtles that are, and may be handled and studied by the amateur:
Young:
Common Snapping Turtle
Soft-shelled Turtles
Sliders
Musk Turtles
Mud Turtles
Diamond Back Terrapin