Plenty of animals bite, but mammals were once thought to be the only ones to chew, at least as it’s usually defined: moving our toothy jaws up, down, and side to side to tear through tough food. But chew on this: the ocellate river stingray, a beautiful spotted fish from the Amazon River, also chews its food.

The discovery not only demonstrates that chewing isn’t special to mammals, but explains how rays, whose skeletons are made of soft cartilage rather than bone, can eat tough prey like shellfish. “I was fascinated by how animals with pliable skeletons can crush hard prey,” says Matthew Kolmann, a biologist at University of Toronto at Scarborough who reports the stingray’s ability Tuesday in