Credit: Current Biology, Dr. Barbara Wueringer
Sawfish use their long, toothed “noses” or rostra to both sense and strike their prey, unlike other jawed fish with elongated snouts that typically have only a single purpose, according to new research by Australian and American scientists.
“I was surprised to see how skilled sawfish are with their saw,” said study co-author Barbara Wueringer at the University of Queensland, Australia, in a press release. “They use their saw to impale prey on the rostral teeth by producing several lateral swipes per second.”
Wueringer’s team used hidden cameras to gather footage of freshwater sawfish, Pristis microdon, feeding on dead fish in captivity. The researchers found that the sawfish strikes sometimes tear their prey in half, after which they manipulate the food onto the bottom and consume it.
The sawfish could also detect weak electrical fields intended to mimic living fish, which elicited a feeding response.
From their recent research, the scientists already knew that freshwater sawfish have thousands of electroreceptors on their rostra that pick up electric fields emitted by nearby animals. These minute canals in the sawfish’s skin can also monitor water movements, making them ideal for hunting in dim water.
Previously, sawfish were thought to use their snouts rather like a rake to sift through the substrate for food.
“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,” Wueringer said.
This new information could help to conserve sawfish, which are critically endangered partly because their rostra can get caught up in fishing gear, perhaps because they are attracted to the fish in nets. Changes in fishing practices in sawfish territory could help to prevent their decline.
The findings will be published in Current Biology on March 6.