Lungs Help Detect Sound

a toad with rippled brown skin sits on the ground surrounded by green and brown

Biological Strategy

Oriental fire-bellied toad

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Image: Alexandre Roux / Flickr / CC BY NC ND - Creative Commons Attribution + Noncommercial + NoDerivatives

Sense Sound and Other Vibrations From the Environment

For living systems, sensing sound and other vibrations is important for communicating and detecting conditions within their environment. Living systems must locate a signal’s source so that they can move toward it (such as when it is food or a potential mate) or away from it (such as when it is a predator). To prompt an appropriate response, living systems must sense these signals, recognize their amplitude or volume (which is sometimes very low), and determine their direction. Living systems must be attuned to signals relevant to them and able to distinguish these from irrelevant sounds to avoid expending unnecessary energy. For example, owls’ ears are asymmetrically placed. This enables them to detect sounds more accurately, which helps them locate small prey at night and avoid wasting energy chasing down irrelevant sounds.

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Amphibians

Class Amphibia (“to live a double life”): Frogs, salamanders, toads

Amphibians live a “double life” by being able to survive both on land and in water. Unlike reptiles with dry, scaly skin, amphibians have smooth skin that needs to be kept moist. Many live in the water through development and start life with gills, and then transition to breathing with lungs. They can get even more oxygen through cutaneous respiration, or breathing through their skin. This class represents the first animal group to be able to efficiently walk on land—aided by the well-defined limbs that gave them a “leg up” on their finned competitors.

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The lungs of the fire-bellied toad allow the toad to hear in the absence of a tympanic middle ear, because sound waves permeate through the mouth and skin, then resonate in the lungs before passing to the inner ears.

Image: Original uploader was Dawson at en.wikipedia / Wikimedia Commons /

Photographer: <a href=http://en.wikipedia.org/wiki/User:Dawson class=extiw title=en:User:Dawson>LA Dawson</a> Oriental Fire-belly Toad, ''Bombina orientalis'' <a href=http://en.wikipedia.org/wiki/Category:Frog_images class=extiw title=en:Category:Frog images>en:Category:Frog images</a>

Image: Visviva / Wikimedia Commons /

Image: Visviva / Wikimedia Commons /

“How is it possible for a land vertebrate to hear if it has neither external nor middle ears to transmit sounds from the outside world to its inner ears? One species that can do so is the fire-bellied toad (Bombina orientalis). It is responsive to a wide range of airborne noises, and is also a versatile vocalist — but how can it detect sound waves? In 1999, Ohio State University researchers Dr. Erik Lindquist and Dr. Thomas Hetherington unmasked its remarkable secret.

“Sound waves travel through its mouth and skin, entering its lungs, where they resonate before passing through the soft tissue around the lungs and into the inner ears. This auditory system should function underwater, too. Indeed, since sound waves travel faster through water than air, it should be more efficient there.” (Shuker 2001:39)

Last Updated August 18, 2016

References

Book

The Hidden Powers of Animals: Uncovering the Secrets of Nature

26/02/2021 | Dr. Karl P. N. Shuker

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