Their stinger is a razor-sharp, barbed or serrated cartilaginous spine which grows from the ray's whip-like tail (like a fingernail). It is coated with a toxic venom. This gives them their common name of stingrays, but that name can also be used to refer to any poisonous ray.
Dasyatids do not attack aggressively, or even actively defend themselves. When threatened their primary reaction is to swim away. However, when they are attacked by predators or stepped on, the barbed stinger in their tail is mechanically whipped up, usually into the offending foot; it is also possible, although less likely, to be stung "accidentally" by brushing against the stinger.
Their stingers are normally ineffective against their main predator, sharks.
