Earless frogs are those that lack a tympanum, which is visible as an eardrum surrounded by a ring of cartilage in most eared frogs. More specifically, the eardrum is called tympanic membrane, the ring is called tympanic annulus, and both are part of the tympanic middle ear, which also includes a bone called columella. Altogether, these structures aid in the transmission of airborne sound to the inner ear.

The amphibian tree of life contains hundreds of species of earless frogs. The most prominent example includes those in the true toad family, Bufonidae, which has approximately 200 earless species out of a total of 609 known species. The loss of hearing structures has occurred multiple times in this and other amphibian families. However, in most cases, male earless frogs have retained the ability to call and species evolved alternative sensory pathways that enable the transmission of sound to the inner ear. For example, the earless Gardiner’s Seychelles Frog (endemic to the Seychelles) use the mouth cavity as a resonating chamber to amplify the sound and transmit it to the inner ear.

Courtesy – Herpdigest Magazine

— (PHOTOGRAPH BY RUDOLF VON MAY)

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