The spectacular snouts of sawfish are revealed as complete hunting weapons, sensing prey and killing them.
The saws, which can grow more than a metre long in some species, have previously been identified as able to sense prey by their electric fields.
Now, researchers have filmed the fish impaling prey on the teeth of the saws.
They suggest in Current Biology that sawfish are more active hunters than previously thought, which could help in their much-needed conservation.
All seven species are listed as Critically Endangered on the internationally-recognised Red List.
The researchers, mainly based in Australia, suggest sawfish may be unique among their peers in possessing a snout, or rostrum, that works both as a sensory organ and a hunting weapon.
"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," said Barbara Wueringer from the University of Queensland, who led the research team.
The research was done using captive sawfish.
Australian regulations on the ethics of animal research meant the team was not allowed to film the sawfish hunting live prey.
Instead, pieces of mullet and tuna flesh were dangled in their tanks, and underwater video cameras deployed to record them.
Weak electric fields were deployed in the water and on the bottom, to mimic the fields produced by live fish, which sawfish sense using the dense arrays of electroreceptors along the rostrum.
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