Are any animals unable to hear their own calls?
Author Liz Kalaugher discusses creatures with calls that are inaudable to them and their potential mates.
Yes. Scientists studying two species of pumpkin toadlet, a tiny frog found in the cloud forests of Brazil, discovered that the males call at frequencies that they, and the females they hope to attract, can’t hear.
Frogs normally have a middle ear containing a bone that transmits sound vibrations from the eardrum to the fluid- filled inner ear, where hair cells detect movement of the liquid and send electrical signals to the frog’s brain.
Pumpkin frogs, however, lack this middle ear, and as such are defined as ‘earless’.
Though they are still able to detect some frequencies, transmitted to their inner ear via body parts such as the lungs, mouth or skull, the toadlets can’t sense frequencies above 1 kHz, even though the males call at 3.7–5.7 kHz.
It’s the only known example of a species not being able to hear its own mating call. Females may instead pick up on the visuals of the call, such as the male’s bulging vocal sac.
Making a noise may appear to put this frog at risk of predation for no gain, but his brightly coloured toxic skin may protect him.
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