The Stingray isn't an aggressive animal, and they don't use the
sting to hunt. It usually stings a person when stepped on, or
brushed up against and startled. The sting is a defensive reflex
done to protect themselves. That is why most people are stung in
the foot or lower leg. Fore more details, please see the sites
Sting rays sting if they feel threatened, this is in there nature because they are eaten by hammerhead sharks (sting rays main predator) in other words if you put your hand over a sting ray and touch it, it will feel threatened and think you are a predator, which will likely get you a sting.