Study sheds light on sawfish habits
Sawfishes are formidable predators that use their toothy snouts both to locate and slice up prey, research has shown.
Previously it was thought the fish used their "saws" more like rakes, to sift through sand in search of food. The new study of captive wild sawfishes shows the saws are lethal weapons that can rip a victim in half.
Sawfish are a type of ray whose most distinctive feature is a saw-like appendage lined with tooth-like structures called denticles. Related to sharks, some can reach a length of 23ft.
Textbooks describe them as bottom-feeders that live on small fish and crustaceans. But researchers who videoed the behaviour of captured sawfish found that in reality they are impressive predators.
"I was surprised to see how skilled sawfish are with their saw," said lead scientist Dr Barbara Wueringer, from the University of Queensland in Australia. "They use their saw to impale prey on the rostral teeth by producing several lateral swipes per second."
The captive fish were fed dead prey, but showed what they would be capable of if hunting in the wild.
"Their strikes were sometimes strong enough to split those fish in half," said Dr Wueringer.
The saws are not only used as weapons, but also prey-locating sensor devices. They are peppered with thousands of sensitive electro-receptors that can detect the electric fields generated by other fish.
"Now we know that sawfish are not sluggish bottom-dwellers as previously believed, but agile hunters that hunt in the three-dimensional space of the water," said Dr Wueringer.
The new view of sawfish might help the critically endangered animals survive, the scientists believe.