Stingrays are no longer the silent residents of the sea that scientists once thought they were. Caught on camera, two different species of stingrays have been discovered making strange clicking noises in a lucky find that has thrilled marine conservationists – but also left them baffled.
“The fact that we have only just realized that these commonly encountered stingrays make sounds demonstrates, once again, how little we know about the oceans,” said marine ecologist Lachlan Fetterplace from the Swedish University of Agricultural Sciences, who led the study.
Nearly 990 species of bony fish are known to make sounds. But elasmobranchs – a group of cartilaginous fishes that includes rays, sharks and sawfishes – have always been considered the stealthy and silent type.
Not so, it seems. Said Fetterplace: “We now have multiple records and sightings of two species of stingrays that emit sounds in the wild,” thanks to a few keen naturalists.
Two mangrove whiprays (Urogymnus aggregate) and a cowtail ray (Pastinachus ater) have been observed by divers who have captured them making strange sounds, which probably serve as a warning signal or defense, Fetterplace said.
Unlike the haunting whale songs that cross oceans or the haunting bird songs that filter through forests, the wild stingrays in these videos emit short, high-pitched, hollow clicks that sound more like a percussion instrument than a Marine animal.
As you can see below, the two species produce clicks of slightly different pitch when gliding through water, an environment that often sounds muted to human ears but is actually full of noisy creatures. make a hubbub.
🔊on! Stingrays: are no longer the silent residents of the sea. Our new article provides the first evidence of not one but TWO species of #ray actively producing sounds https://t.co/0bPJpZpMHT @BWueringer @jdelgadoesteban @MotherOfRays @SLU_aqua @fish_thinkers @ESAEcology 1/ pic.twitter.com/uvObWfElM3
—Lachlan Fetterplace (@fiskeforbrains) July 19, 2022
Based on what little is known about the range of sounds that elasmobranchs can hear, Fetterplace and colleagues hypothesized that stingrays and their predators can indeed hear these clicks, which are within the expected range of hearing (40 -1500Hz).
This led them to propose that stingrays could produce sounds to ward off or scare away approaching predators, so that the stingrays could flee quickly.
In all recorded sightings – captured using handheld digital cameras, in 2017 and 2018 near the Gili Islands in Indonesia and on the Great Barrier Reef – stingrays began making “clicks” as they approached of the observer, then stopped when the diver or the ray moved away.
But it could also be that the sounds of the rays are a call to arms, to recruit other rays when you feel threatened, as one diver observed.
The question is: how does such a flat animal, whose body parts are streamlined for an aquatic world, make a sound other than comma?
The researchers think the rays might make these sounds the same way humans click their fingers or click their tongues.
“We can’t be sure how the rays produce the sounds,” said co-author and marine scientist Joni Pini-Fitzsimmons of Macquarie University, “but it appears to involve rapid movement of the head or jaw and spiracles, an opening behind the eyes used for respiration.”
Stingray noises have been observed before, but rarely. Decades ago, a few captive stingrays were observed making “crackling” and “rumbling” sounds when feeding (let’s be honest, who doesn’t); there were also anecdotal reports of cowtail stingrays making loud clicking noises as they flee from divers in murky waters.
This, however, appears to be the first documented evidence that animals actively produce sounds without being provoked.
Further research is needed to appreciate the hearing range of elasmobranchs, “especially given the limited number of examinations in this group to date”, the researchers write.
“Elasmobranchs are most sensitive to low-frequency sound between 40 and 1500 Hz, with peak sensitivities between 200 and 400 Hz, but audiograms have only been produced for 10 species.”
Considering how animals perceive the worlds they inhabit in a way we really can never really understand, we shouldn’t be surprised but continually marvel at new discoveries that upend what we thought we knew about life on Earth.
The videos only capture a few examples of two stingray species making noise, which could be because they only do so very occasionally, when threatened.
Some species of stingrays are solitary creatures.
“They can also be quite difficult to study because they are often very mobile and elusive,” said Audrey Looby, a marine community ecologist at the University of Florida, who was not involved in the work. Told National Geographic.
Despite the challenges, with more than 1,200 species of elasmobranch known, researchers believe many more sightings could soon surface now that people know what to listen for.
The research has been published in Ecology.