This is a baby Common Snapping Turtle. While they have a fairly normal-sized shell from the top, the bottom side of their shell is very small. Like Soft Shelled Turtles, Snapping Turtles cannot pull their heads into their shell. Both have adopted the "best defense is a good offense" attitude, meaning that they tend to bite first, and instead of asking questions later, they settle for biting again. Both have long necks, and they can strike very quickly.