Whilst this question might at first seem obvious, it is more complex than it appears. Whilst almost all life has the capacity to hear sounds within their specific audible ranges, this can often manifest itself in different ways.
Physically protruding ears are associated with mammals in particular, and almost all animals, from bats, to dogs, to pigs, and apes, all have this same distinct feature.
The same cannot be said for birds, reptiles, amphibians, and fish (to name a few), all of which have the capacity to hear, but do not possess a physical, outward protrusion for hearing.
Why Do We Have Ears?
Speaking for human beings first and foremost, whilst we do not theoretically need our outer ears to hear sound, the shape and design of our ears do play a significant role in our ability towards directional hearing.
The cupped, dish-like shape of our ears allows us to direct the sound into our ear canals and ear drums.
This can be seen when we turn our heads to listen in a certain direction. We can still hear the noise perfectly well, but when we direct our ears towards the source of the sound, we can get a much more detailed audio image.
How Do Our Ears Work?
Without our outer ears, we would have a much limited range of hearing, and almost no directional capabilities when it came to channeling sound directly inside.
It is the shape of the outer ears which channel the vibrating air down our ear canals and into our eardrums, creating a receptory vibration, which is then interpreted by our brain as specific sounds.
Can Fish Hear?
Fish can indeed hear sound, although it is not as vital a part of their existence as it is for us. Whilst they do use their ears to detect predators, much of their awareness comes from vibrations in the water, as well as sight and taste (depending on the fish in question).
Do Fish Have Ears?
Whilst fish do have ears in the technical sense, in that they have receptive body parts that give them the ability to hear sound, they do not have them in the same way we do.
Of course, visually, fish do not have outward protruding ears. This is down to many factors, such as the effect of their environments, and the need for streamlined swimming.
If fish had ears in the same shape we did, then their swimming ability would be significantly hindered. They would create unnecessary drag, and would become homes for parasites and debris.
Whilst their fins are able to move and shift to match the current, ears do not have the same range of motion, and so would not work from a movement perspective.
Where are the Ears on a Fish?
Whilst they do not have outwardly protruding ears, they do have inner ear hearing, although this only loosely resembles our own.
First of all, fish do not have eardrums. This is an evolutionary trait, necessitated by the fact that their bodies are submerged in water.
You will know yourself that water and eardrums/canals do not mix, and it has the opposite effect, making you able to hear less.
What fish do have however, is a feature called an otolith.
What Is An Otolith?
These are small bones located inside the fish’s head, and when vibrations are created in the water, the vibrations travel into the fish’s head, striking the otolith, before their brains then translate the vibrations into sound.
Are They Effective?
Their effectiveness is debatable, and it very much depends on the kind of fish, and the environment they reside in.
Most agree that whilst they do have the ability to recognize sound and pinpoint a general direction, they lack the same degree of accuracy and clarity that we have, both as a direct result of their physical makeup (i.e lacking directional ears and drums), but also because of the water they call their home.
As well as the otoliths, fish have several other components that compensate for their poorer hearing, most notably lateral lines, and swim bladders.
What Is A Lateral Line?
A lateral line is a complex set of organs that are capable of detecting acoustic signals (or vibrations in the water), allowing the fish to have more or a sense of their environment, albeit only over short distances.
Whilst the lateral line can’t detect too much, it does give the fish the ability to detect what fish are around them and where they are positioned. They also allow predatory fish (such as sharks) to find their prey, and prey fish to sense when something is amiss in their environment.
What Is A Swim Bladder?
Less common, and only possessed by certain species of fish, a swim bladder is an organ that not only allows the fish to stay upright in the water, but is also connected to the ear system, and is capable of sensing vibrations.
The swim bladder is incredibly sensitive, and when vibrations strike it, the signal is carried up a series of sensitive bones, before reaching the ear system and causing that to vibrate too.
This is then translated into specific sound by the fish’s brain.
The benefit of a swim bladder is that it acts as an amplifier inside the fish’s body, almost like a hearing aid in human beings.
This makes fish who possess this organ some of the best listeners in the ocean.
And there we are, a rundown of everything you need to know about fish, their auditory anatomies, and the methods they use to judge their surroundings, hunt for food, and sense danger.
Whilst unusual in their design, their vibrational sensitivity shows the true genius of nature, and how it can continually adapt when new problems arise.
Bet you feel bad for tapping on that fish tank now, huh?