March 23, 2012
At first glance, the sawfish looks like nature’s awkward version of a double-sided garden rake. This highly endangered species is a kind of ray. Previous observations of sawfish predatory behavior pinned them as slow-moving bottom-dwellers.
But a study this month in Current Biology shows that the freshwater sawfish is no rake-nosed dope. In fact, the sawfish uses its toothed rostrum (the saw) not only to detect its next meal, but also to attack and impale its prey, sometimes slashing at schooling fish or even cutting tissue out of whales. Their strikes can be strong enough to cut a fish in half.
The study shows that the saw is used both to detect prey and to attack it. Other fish in the shovel-nose family can’t do both—and previously, researchers thought the sawfish followed suit. Unlike other jawed fish whose snouts are used for one or the other purpose, the sawfish has thousands of electroreceptors that enable them to detect the electromagnetic field produced by other animals, and they have tiny canals on their skin that register water movement in their three-dimensional hunting environment.
This new reputation may lead to changes in fishing practices allowed in sawfish territory—their saws often become entangled in fishing gear, contributing to their swift decline.
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