Sharks and rays are considered to be strong, silent types—they possess no voice boxes, or other anatomical structures associated with vocal communication. Or so we thought.
Then Spanish photographer J. Javier Delgado Esteban filmed a juvenile mangrove whipray (Urogymnus granulatus) while he was snorkelling off Magnetic Island on Australia’s Great Barrier Reef.
When Esteban approached, the ray made loud clicks. Each sound visibly coincided with a contraction of its spiracles—openings behind the eyes that rays use to aid breathing.
Marine ecologist Lachlan Fetterplace saw the video on Instagram, contacted Esteban, and started investigating. They assembled anecdotal reports and two other recent videos from Australia and Indonesia showing an adult whipray and a cowtail stingray (Pastinachus ater) making similar tok-tok sounds.
“These are widespread species, found off the coast in highly populated areas,” says Fetterplace. Yet researchers hadn’t noticed the sounds at all.
Many mysteries remain: how the rays are making the clicks, exactly what they’re using them for, and how many other rays and sharks may also be capable of sound. “Is it a really widespread thing that they rarely do, or is it something that’s commonly done, but only in a few species?” says Fetterplace.
He’s now questioning what else we might have missed—simply because we weren’t looking for it.