Frogs are pretty unique-looking animals, from their bulging eyes and long tongues to their sticky, webbed feet. If you’ve ever looked closely at one of these bizarre amphibians, you’ve probably noticed the area where their ears should be looks especially unusual. Do frogs actually have ears at all, and if so, how do they use them to hear? Furthermore, how are they different from our own ears?
Read on to learn more about frogs’ ear anatomy, their unique sense of hearing, and how their ears work when processing auditory stimuli. We’ll also talk a bit about how their ears differ from ours and other animals’ ears as well as why they’ve evolved so differently from ours.
Do Frogs Have Ears?
Although it doesn’t look like it at first glance, frogs actually do have ears! They’re just structured in a way that’s a bit different from our own, so they understandably look strange to us. Most animals’ ears consist of two or three unique parts: an outer ear, a middle ear, and an inner ear. Frogs have middle and inner ears but no outer ears! Instead, they have a tympanum, an external hearing structure similar to an eardrum, in place of an outer ear.
Some animals, including most mammals, have all three structures: an inner, middle, and outer ear. Other animals, including most reptiles and amphibians, lack an outer ear, also known as the pinna, entirely. This includes not only frogs but also newts, salamanders, lizards, snakes, crocodilians, and turtles. The middle and internal ear are not visible externally. Only the outer ear, the fleshy part with all its folds and creases, is visible on (most) mammals.
Interestingly, a handful of more primitive species of mammals, like echidnas and platypuses, also lack a typical pinna like frogs, other amphibians, and reptiles. Instead of a tympanum, though, they actually have a modified, much smaller external ear structure in its place. Birds also have a modified outer ear that is essentially a small funnel.
How Do Frogs’ Ears Work?
Despite looking a lot different from our own, frogs’ ears work in a surprisingly similar way!
As sound waves are picked up by the frog’s tympanum, it vibrates. The tympanum then transports the sounds and vibrations to the middle ear. The middle ear amplifies the sounds and sends them to the inner ear. Finally, the inner ear and its finely-tuned hair cells “convert” the sounds and vibrations into complex electrical signals. These signals get sent to the frog’s brain. The frog’s brain then interprets those signals to find food, hide from predators, and even locate potential mates!
Incredibly, frogs use a lot more than just their ears to pick up sound waves. Many species also rely on subtle vibrations surrounding them in their environments to interpret information. Their skin, lungs, and even mouths are all uniquely equipped to expertly hone in on these vibrations!
Depending on how loud a sound is and how heavy its vibrations are, a frog can turn its head and body to locate exactly where it’s coming from. These vibrations also help frogs to stay balanced, determine how far they need to jump, and even locate exactly where predators are lurking. They can keenly differentiate between certain sounds and their vibrations, like another nearby frog hopping around versus the sound of a hungry snake slithering about looking for its next meal.
Do Frogs Have Good Hearing?
Frogs have very good hearing. They are able to pick up on certain (high and low) frequencies that humans and other animals can’t. Many species can even “tune” their ears to pick up certain frequencies, vibrations, and sounds while “tuning out” background noise!
Like we touched on earlier, frogs are able to keenly interpret all kinds of sounds with ease. Although their eyesight isn’t quite as well-developed, their capacity for hearing is surprisingly complex! Since they’re able to use more than just their ears to pick up sounds, they’re very sensitive to their surroundings. By using their lungs, mouths, skin, and ears to pick up on all kinds of vibrations and sound waves, they know what’s happening around them at all times.
Frogs are also very skilled at interpreting what certain sounds mean. They can identify the sounds of nearby predators and understand those sounds as a signal to stop croaking and become very quiet to evade danger.
Alternatively, they can also tell when other frogs are nearby and will amplify their own calls to attract them. They can hear so well that they can differentiate between members of their own species and other species’ unique croaks and calls. This is very useful for mating and socializing with one another!
Do Any Frogs Lack Ears Entirely?
All frogs have some kind of hearing structure designed to pick up sounds and vibrations. However, while all frogs lack external ears, some species also lack middle ears! Very small sooglossid frogs like the Gardiner’s Seychelles frog only have an inner ear structure. This means they have to rely heavily on vibrations to interpret auditory stimuli.
Instead of using their middle ear to amplify sound waves like most frogs, sooglossid frogs hear with their mouths! They were believed to be entirely deaf for many years, but recent studies have disproven this. In fact, they can hear their own calls and even differentiate between other sounds despite having no middle ear structure.
More research is still needed to better understand exactly how these frogs’ mouths work so well to pick up sound. Many theories exist, but most researchers currently believe the species’ unique hearing has something to do with a thinner-than-usual amount of tissue between the frogs’ mouths and inner ears. Since there isn’t much tissue between the two structures, the tiny frogs can likely easily transmit sounds from their mouths directly to their inner ears.
The photo featured at the top of this post is © iStock.com/ca2hill
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