A new study published in the September 2nd journal of Proceedings of the National Academy of Sciences (PNAS), explains how one of the world’s smallest frogs, the Gardiner’s frog, is able to hear.
Gardiner’s frogs, native to the Seychelles islands, lack the typical middle ear and eardrum needed to hear sounds. Yet they are still able to make croaking sounds and hear the calls of other frogs.
Lead researcher Renaud Boistel of the University of Poitiers in Poitiers, France, had this to say in a press release, “These small animals, Gardiner’s frogs, have been living isolated in the rainforest of the Seychelles for 47 to 65 million years, since these islands split away from the main continent. If they can hear, their auditory system must be a survivor of life forms on the ancient supercontinent Gondwana.”
In the study, European researchers used X-ray imaging to look at the frogs’ heads. They found that the mouth works like an amplifier, taking in and transmitting sound waves from other Gardiner’s frogs, enabling them to hear one another. An evolutionary adaptation unique to Gardiner’s frogs is responsible for this hearing mechanism: the layers of tissue between their mouth and inner ear are thinner and fewer in number than what is found in other frogs.
Photo Credit: R. Boistel/CNRS