Dogs bark. Frogs croak. Birds chirp. Certain animals are known for their sounds. Others seem to be silent. But a study published last October in Nature Communications suggests otherwise about some of these so-called quiet creatures.
Researchers recorded 53 species thought to be silent. The results? “Every single species we recorded made sounds,” Gabriel Jorgewich-Cohen, a coauthor of the paper, told TIME for Kids. The study suggests that the animals use vocalizations to communicate.
“Some animals, they’re really highly vocal, like frogs and birds,” Jorgewich-Cohen says. “We tend to consider other animals to be nonvocal. And then we don’t give them as much attention.” Turtles are thought to be silent. But Jorgewich-Cohen says he heard vocalizations from them. It was during a different study in the Amazon rainforest. (See “Listen In.”)
Maybe the widespread scientific view was wrong, Jorgewich-Cohen thought. The only way to find out was to really listen. “I tried first with my own pets,” he says. One of those was a turtle named Homer. “I found sounds there. So I decided to record as many turtles as I could.”
Ultimately, the study included 50 turtle species, a reptile species called the tuatara, the South American lungfish, and the Cayenne caecilian, an amphibian that looks like a worm.
Each animal was recorded with advanced equipment for 24 hours. Jorgewich-Cohen listened to more than 1,000 hours of audio to document the sounds.
The animals’ ability to vocalize might be linked to a common ancestor. It’s a fish that lived 407 million years ago. More research is needed to test this conclusion. Jorgewich-Cohen encourages this. “There is a tendency for people to learn something like, for example, turtles are nonvocal. And then they just keep this as being a reality,” he says. “It’s good to keep curious and try different stuff.”
Millions of animals live in the Amazon rainforest. Some are noisy. Others are thought to be silent. But researcher Gabriel Jorgewich-Cohen heard turtle vocalizations in the Amazon. Have Indigenous people known about these sounds?
Zoologist Irene Ballagh thinks it’s possible. When she was growing up in New Zealand, her mom told her about tuatara vocalizations. But scientists said the tuatara is silent. Those researchers, she told Scientific American, “were not ever thinking to ask local people” about what they’d seen and heard. She hopes future research incorporates the knowledge of local and Indigenous people.