Stingrays chew?!

What is it about?

Freshwater stingrays are found throughout the Amazon and has evolved to eat prey that other stingrays either can't eat, or don't. These rays are the only elasmobranchs (sharks and rays) to eat insects - which are difficult to eat and digest. We filmed rays feeding on different kinds of prey and used CT (computed tomography) scanning to examine how their jaws move while feeding. We found that freshwater stingrays suck prey beneath their bodies to capture it. Stingrays use side to side motions of their jaws to tear tougher kinds of prey, like insects, apart. These motions are similar to how other animals chew. Some species of freshwater rays can also reorient their teeth to make them better capable of grabbing and shredding insects.

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Why is it important?

These transverse jaw motions are similar to what is seen in mammal chewing - an example of two groups of animals finding a similar solution to a common problem - how to eat tough prey materials. This finding is a fantastic example of convergence in behavior and ecology, faced with stubborn prey materials, these freshwater stingrays chew their food just like some mammals do. The flexibility of their jaws and feeding behaviors may have been how these rays, when they invaded freshwater Amazon habitats, adapted to new diet opportunities.