Thursday, 5 September 2013

'Ear 'Ear

Imagine being able to fit onto the nail of a thumb. Everything about you would be miniaturised. This is the case for the one of the world's smallest frog the Gardiner's frog.

This little amphibian can reach the size of 11mm (1.1cm) long once matured, but are born only 3mm in length. The males are slightly shorter than the females and grow to a maximum of 8mm. These miniature frogs are at a threatened level and are marked as vulnerable by conservationists.

The amazing thing about this frog is that it does not have an middle ear. The middle ear was thought to be crucial in hearing, as this is the part where the eardrum vibrates and previously the frog was thought to be deaf. This initial belief was dismissed via a new behavioural experiment.

The frogs produce a high pitched squeaking, which scientists recorded. They then played back the recording to the wild frogs and observed their behaviour. The wild frogs responded to the squeaks, which proved that they were able to hear.

Next was to find out how the ear less frog was able to hear a sound without the presence of an eardrum. The research team from the Nature Protection Trust of Seychelles produced simulations in trying to predict how the frog's head responds to the sound waves. They played sounds at the same frequency as the frog's own calls, and found that the mouth of the frog resonated like an ear drum, amplifying the sound. Furthermore it was found that these frog's had thinner layers of tissues between their mouths and inner ear, which allowed sound waves to be passed much more easily between the 2.

Although this is an great discovery and it leads us to understand the anatomy of the Gardiner's frog some more; one would have thought that being in a colony, the frogs must have needed to communicate between each other, and consequently they would have been able to respond to the calls which they make and subsequently there would have been a premise for the development of a new technique of hearing without the presence of a middle ear.

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