Stingrays - named for their barbed, venomous tail spine - have teeth that enable them to crush and eat invertebrates such as clams, mussels, and oysters. Like their shark relatives, stingrays possess special sensing organs called ampullae of Lorenzini that can sense the natural electrical charges of potential prey and aid in hunting. Stingray species vary in size from small, palm-sized specimens to large specimens reaching fourteen feet in length.