Scientists have discovered how the terrifying snouts of sawfish act as complete hunting devices - sensing prey as well as killing it.
The saw-like snouts are used to sense the electric fields produced by other types of fish - their prey.
But now scientists have watched the animals and seen that the teeth of the saws are used to kill their prey too.
They say that sawfish may be unique among fish, in having a snout that can sense things and be a weapon.
Dr Barbara Wueringer, one of the scientists in Australia who discovered this, said about the snout: "I like to call it an antenna and a weapon, because that's what it is - it helps them to find the prey, but then also to kill it."