Frog Uses Mouth to Hear, Not Ears
Animals are astonishing works of nature. For decades, researchers have studied how animals live in the wild, hoping to uncover more about these incredible beings. In a new study, researchers focused on the little, dime-sized frog called the Gardiner's Seychelles frog. Even though this species of frogs might be small enough to sit on one's fingernail comfortably, their mouse-like shrieks can draw a lot of attention. The team of herpetologist, who are researchers who study amphibians and reptiles, from the Centre de Neurosciences Paris-Sud, discovered that these frogs use their mouths to enhance their hearing ability.
Before the researchers set out to observe the frog, they knew that this species of frogs do not had a middle ear, which is responsible for hearing in most animals and humans. Around six percent of frogs are deaf. Despite not having this structure, which is made up of many bones and muscles, these little frogs appear to still be able to hear. This prompted the researchers, headed by Renaud Boistel, to use X-ray imaging to analyze whether or not there was another part of the frog's anatomy that allowed it to hear.
The researchers created a simulation model of the frog's skull to see what could be responsible for the frog's hearing. They first ran simulations through the skull and found that the sounds were greatly weakened by the time they reached the inner ear, indicating that the frogs would not hear anything. The researchers then tried to see if vibrations were carried to the ears via the lungs. They found that since the frog's lungs were extremely small, they would not be able to carry out the vibrations effectively. The team then decided to add the mouth to the simulation model. The researchers discovered that the frog's mouth appeared to be able to amplify sound.
"Only the oral cavity has the ability to resonate at 5,738 Hz," Boistel wrote in his paper. Frogs communicate at an average of around 5,710 Hz. "Thus, the oral cavity appears as the ideal frequency-tuned candidate to amplify the acoustic signal."
The study was published in the Proceedings of the National Academy of Sciences (PNAS).