Dozens of Species Thought to be Dumb Are Making Sound : NPR

In the animal kingdom, some creatures are famous for the sounds they make – birds and their songs, cats and their meows, frogs and their rib bits.

But some animals are quieter mysterious. Do turtles talk? What about other lesser-known vertebrates such as tuataras, caecilians, and lungfish?

The answer is yes, according to a new paper in nature communication with evidence that many species thought to be mute do, in fact, vocalize — and the researchers recorded it on tape.

Do you want to hear the evidence? Here is the sound of a southern New Guinea giant softshell turtle. And here is a caeciliana limbless amphibian that lives hidden underground.

Gabriel Jorgewich Cohen, an evolutionary biologist working on his PhD at the University of Zurich, is the lead author of the paper.

He explains that this project started after he read about a turtle in the Amazon making noises, and he began to wonder what little noises his own turtles were making. He came into contact with a researcher from his former university in Brazil who had created a tool that would be crucial to the research.

“He developed a kind of hydrophone, which is basically a microphone that goes under water,” explains Jorgewich Cohen. “I took it home and started taking in my own pets. And I really heard them making a lot of noises.”

The project was done. He traveled to eight or nine institutions in five countries, looking for species that were thought to be mostly mute. He recorded fifty species of turtles, as well as caecilians, tuataras (a reptile now found only in New Zealand), and lungfish (fish that can breathe air).

And it turned out, no of them were dumb. “Basically, every animal I recorded made noise,” says Jorgewich Cohen.

He says the findings point to a common ancestor some 407 million years ago.

“Sometimes it’s surprising how much we still don’t know about things that aren’t uncommon per se, but live next door to us,” said Neil Kelley, a paleontologist at Vanderbilt University.

Kelley says the article’s conclusion, mapping these vocalizations onto the evolutionary tree, makes sense. He notes that there are unique challenges in studying animal sounds over millions of years.

“It’s very difficult to trace that in the fossil record because clearly sounds don’t freeze and most vocal equipment is based on soft tissue,” he notes.

It is important to note that sound production and hearing are different things. Snakes, for example, are known for their hissing sounds. But they don’t think they can hear themselves – or each other – hissing.

And a turtle making sounds doesn’t necessarily mean it’s communicating that way, says John Wiens, a professor of ecology and evolutionary biology at the University of Arizona.

“I think that making sounds and acoustic communication are a bit mixed up,” he says of the paper.

Jorgewich Cohen says that while the research team isn’t sure what all the sounds they collected mean, they used several strategies to identify sounds used for communication — including using cameras to correlate sounds with behaviors that convey some sort of intention. could show, and only included sounds that were repeatedly produced and appeared to be correlated with social behavior.

Wiens says that recording these sounds is an important step towards greater understanding.

“If you don’t record and report these sounds, there’s no reason anyone should study acoustic communication in those things,” he says. “You don’t even know they’re making noises.”

The next step, he says, is figuring out what these animals might actually be saying.