River turtle talk recorded by researchers
18 August 2014 Last updated at 09:10 BST
Scientists have managed to eavesdrop on some very unusual underwater chatter.
Their recordings have revealed that giant South American river turtles, previously thought to be silent reptiles, communicate with each other using soft croaks.
Over three years, a team of researchers recorded sounds emitted by adult turtles and by hatchlings.
In this very short clip, you first hear a recording of the sounds made by adult turtles communicating with one another; then the second type of sound is a recording of adults and hatchlings communicating.
Sound clips courtesy of the National Institute of Amazonian Research