Video: Stingrays chew their food—just like mammals

Here’s some food for thought: Aside from mammals, most animals don’t chew their grub. Instead, they shred it into hunks and choke it down, much like crocodiles or great white sharks. Now, for the first time, scientists have caught stingrays in the act of chewing. The researchers were first tipped off when they noticed ocellate river stingrays, a freshwater fish in South America, spitting jets of water to flush out insects from the river silt before slingshotting their jaws forward to capture the nutrient-rich morsels. But how could the rays digest the insects’ hearty insides if they didn’t chew through their tough exoskeletons first? To find out exactly how this was possible, researchers plunked four stingrays into glass-bottomed tanks and pointed high-speed video cameras at their mouths. The scientists were astonished when they tossed in dragonfly larvae and the rays began chomping away (as seen above). The lateral, grinding jaw motion they used was similar to that of mammals like goats and humans, they report today in the Proceedings of the Royal Society B. The researchers say it’s likely that other ray species also chew their food—especially if they need to shred away fibrous materials from insects, shrimps, or other prey items—and have begun to examine stingrays from all over the world to see whether they also gnaw their prey.