Turtles ‘Talk’ to Each Other, Parents Call Out to Offspring

A South American giant river turtle. Camila Ferrera

The film Teenage Mutant Ninja Turtles has topped box offices for two weeks in a row, despite poor reviews. It’s no surprise, of course, that the film is wildly scientifically inaccurate—it is about human-sized mutant turtles, of course. But in one important way, the science flies: Turtles really “talk.”

Sure, they can’t speak English (so far as we know), but real-life turtles communicate underwater with low-pitched calls that they use to help them travel together and to find mates, says Richard Vogt, a researcher at National Institute of Amazonian Research in Manaus, Brazil.

Much of Vogt’s work focuses on Giant South American river turtles, which migrate from beaches into dense, flooded forests. “You're watching a sand beach in the Amazon, and in a manner of minutes, 200 turtles all come out at the same time and start sunning. How do they decide to do it?” By talking to each other, he says.

Vogt and colleagues have now recorded detailed data on vocalizations of eight species of turtles, and other species tested have all been found to talk. “We believe all turtle species vocalize,” says Camila Ferrera, Vogt’s colleague, who also works with the Wildlife Conservation Society.

This stands in marked contrast to the prevailing belief held a generation ago—that turtles were basically “deaf and dumb,” and couldn’t communicate underwater, Vogt says. It was already known that certain land-dwelling tortoises can vocalize, however.

In a series of papers over the last few years, the latest of which was published in the journal Herpetologica, Vogt and colleagues have found that adult Giant South American river turtles (Podocnemis expansa) can communicate back and forth with hatchlings, which helps the young migrate to the right location. This is the first proof of post-hatchling parental care in any kind of turtle, and really shows that they are more sophisticated than previously thought, Vogt says. baby-turtles-sound-equipment Baby giant river turtles hatching and crawling into the Rio Trombetas, Brazil. Camila Ferrera

This “has huge implications for conservation programs,” says Gerald Kuchling, a researcher at the University of Western Australia who wasn’t involved in the present research. Often conservationists move nests to protect baby turtles, but “this could be detrimental rather than helpful by disrupting their integration into the population.” In other words, if parents can’t find their young, they won’t be able to help them migrate to the right location.

The scientists also found that the baby turtles can talk to each other while still in the egg, and that this may help them to synchronize when they hatch. Vogt and his team have shown this takes place in leatherback and olive ridley sea turtles.

In finding that turtles rely on vocal communication, the research shows that they are are also more likely to be negatively affected by noise pollution than previously thought. Human-made sounds, like those from ship traffic or acoustic testing, could interfere with turtle communication. camila-ferrara-hydrophone Researcher Camila Ferrera uses recording equipment to listen to vocalizations of baby turtles, in the Amazon rainforest. Camila Ferrera

“We were ignorant regarding underwater vocal communication in turtles and did not consider effects of noise pollution, thus  virtually nothing is presently known on its impacts,” Kuchling said. “There is now some urgency to find out if and which noises disrupt their functioning.”

It also shows that the animals and their social lives are more complex than assumed, says Whit Gibbons, an emeritus professor at the University of Georgia who studies turtles. “Turtles are as cognizant as many other vertebrates [animals with backbones] in many ways, just slower,” Gibbons tells Newsweek.

“These pioneering studies open a completely new field for turtle behavioral research,” Kuchling adds.

So far, the scientists have recorded more than a dozen different types of vocalizations among the giant river turtles, the exact function of which aren’t all completely known (although none of the calls, as far as Vogt knows, translate to “Cowabunga”). To date, more than 40 different species of turtles have been shown to make noises, Vogt says.

Why wasn’t this known sooner? There are several reasons, according to Vogt. For one, turtles are not too talkative; sometimes Vogt said he would have to wait hours just to hear a single peep. The sounds they emit in water—where the bulk of their communication takes place—are also very low-pitched, as these sounds travel farther underwater. The sounds are so low they cannot easily be heard by adults over the age of 40 and are quiet enough that they can easily be masked by the sound of a swimming human.   vogt-turtle-shore Richard Vogt holding a South American giant river turtle, as a younger man. Richard Vogt

“Flippers and air bubbles are enough to drown out the sounds turtles make,” Vogt says.

The sensitive hydrophones Vogt uses to eavesdrop on these reptiles also run several thousand dollars and are not easy to come by; he had to sign waivers saying he wouldn’t use the material for spying or interfering with naval communications.

Sadly, another reason that it took so long to figure out that turtles talk is that the animals stop vocalizing when they are domesticated or put in zoos, Vogt said.

“If you put them in a wading pool, they vocalize for a few days and then they stop,” he says. In zoos “there’s nothing there; they’re not talking.”

Vogt has studied turtles for 50 years, and was recently given a lifetime achievement award for altering “the entire course of a field of study” not once, but twice, according to Turtle Survival Magazine. Before his work on turtle vocalizations, Vogt and scientist Jim Bull showed that warm sand produced more female turtles, while colder sand did the opposite. Vogt’s newer work on vocalizations may have as much impact as the earlier did on conservation measures, according to the magazine.

“We must ask ourselves if we are disrupting important transference of learned behaviors from mother to offspring by keeping hatchlings in captivity for weeks to years before their release,” Turtle Survival notes. “We may unwittingly be doing more harm than good, much like how many early turtle conservationists incubated turtle eggs at cool temperatures, thereby producing only males, before [Vogt’s] seminal work demonstrated the error of their ways.” richard-vogt-student Richard Vogt recording turtle "talk" with doctoral student Virginia Bernardes, in Brazil's Rio Trombetas. Richard Vogt

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