Stingrays are cartilaginous fishes in the phylum Chordata, and composing the family Dasyatidae. They are relatives of sharks and live mostly on the marine floor, where they hide their flat bodies under loose sand and soil and attack prey with their barbed, venomous tail. The barb on the tail is actually a modified dermal denticle, or fish scale, that has evolved to house venom glands, which are useful in killing larger predators or catching smaller prey. Stingrays live in both saltwater and freshwater locations.
Stingrays are fairly commonplace, living in many different oceans and climates, and are often found in tropical zones, where the warm oceans allow them to remain still without freezing to death. Many species have no teeth, only a soft vacuum-like mouth, while others have evolved bony plates to crush shells. They are not aggressive towards larger animals or humans, but stings to occur when they are startled or stepped on; conservationist Steve Irwin was famously killed, almost instantly, by an uncommon stingray stab to the heart while filming a documentary.
The world's largest recorded stingray weighed between 500 and 900 pounds, and was almost seven feet long and wide (excluding tail). It is shorter than the previous record, a 14-foot stringray (including tail), but much heavier and fatter; this might be the largest freshwater fish ever found.