Do Fish Have a Tongue? Surprising Truth Behind Fish Tongues
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Fish are among the oldest creatures on Earth. Despite this, there’s always something new and exciting to learn about them. Fish are just that diverse and full of mysteries.
One question people often ask is, “Do fish have tongues?” Well, it’s complicated. There’s no clear-cut yes or no answer. Fish are anatomically different from other animals; after all, they can breathe underwater!
Sometimes, though, they show some similarities to other animals, but even then, these similarities are just skin-deep.
You’ll see what I mean. So, if you’re curious to learn more about fish mouth anatomy, fish “tongues,” and how they work, keep reading. I’ll cover everything in wide detail. Let’s start with the basics…
Overview of Fish Mouth Anatomy
Well, the obvious things first— fish have mouths, and their function is feeding. So far, so good. But here’s where it gets complicated. There’s not one unique type of fish mouth, and not all fish have the same inner mouth anatomy.
A fish’s mouth size, shape, teeth, and tongue vary greatly depending on the fish species and its feeding style.
Let’s take a look at the different types of fish mouths and their anatomical features. We’ll start from the outside and work our way in.
Fish Outer Mouth
The outer mouth includes the fish’s lips (and sometimes teeth and tastebuds). You can best observe the outer mouth when viewing a fish from the side. The mouth can sit high or low on the fish’s face.
We can split fish mouths into multiple categories, depending on the mouth’s orientation:
This is the most common type of mouth in fish. You’ll see it in species like tetras, gouramis, freshwater sharks, and barbs. A terminal mouth sits in the middle of the face. It points straight ahead, and the lips are usually in line with the eyes.
Terminal mouths are perfectly centered, at an equal distance between the top and bottom of the head.
Thus, the upper and lower jaws are symmetrical. And here’s something cool… fish with their mouth sitting in the middle also usually feed in the middle of the water column!
This mouth type is the most versatile. Its positioning, jaw size, and symmetry allow these fish to open their mouths wide and even thrust their jaw forward.
Fish with terminal mouths are almost always omnivores and feed on other fish.
Superior mouths point upwards. The tip of the mouth might be in line with the eyes or slightly higher. In any case, this mouth type is very easy to distinguish, thanks to its upturned position. You can see this mouth type in hatchetfish, danios, and archerfish.
In superior mouths, the lower jaw is longer than the upper jaw. This type of mouth is less flexible and usually functions more like a dustpan or a scoop. These fish strike from below, sweeping the prey up into their mouths.
Fish with superior mouths are ambush predators who rely on momentum to catch their prey. They’re also usually top-layer swimmers.
They might even feed at the surface, where they prey on insects and other unsuspecting fish. Fish with superior mouths might be carnivorous or omnivorous.
These mouths are downturned. The tip of the mouth sits below eye level, and the upper jaw is longer than the lower jaw. As you might have noticed, the mouth positioning tells us about a fish’s diet and location in the water column.
A downturned mouth means the fish typically swim and feed at the bottom. Their diet might be omnivorous or herbivorous. Fish with inferior mouths typically feed on detritus, algae, and invertebrates like snails and shrimp.
Sometimes, inferior mouths are very flexible. Suckermouths, for example, are downturned but also protrusible.
This subtype of downturned mouth is most common in herbivorous bottom-dwellers. Examples of fish with downturned mouths include loaches, Corydoras, and geophagus fish.
Fish Inner Mouth
At first glance, most fish species have simple mouths, similar to other animals. The fish mouth has a roof and a floor and typically includes organs like teeth and a “tongue” (more on this later).
But of course, it’s not so simple. Not all fish have the same inner mouth organs, and organs like teeth differ greatly in shape, function, and location from one species to another.
Let’s delve deeper into this.
All fish have teeth, but their location varies. The teeth might sit on the lips, the upper and lower jaws, the tongue, the roof of the mouth, or inside the fish’s throat (also known as pharyngeal teeth).
Like mouth shapes, fish teeth can differ greatly from one species to another and often reflect the fish’s dietary habits. By shape, we can classify teeth into four main categories:
Tapered, pointy, and sharp teeth. Such teeth are suited for latching onto prey and shredding through flesh. These are among the most common and are usually present in carnivorous but also omnivorous fish.
Conical teeth that are large and sharp are called “canines.” Canines are present in infamous carnivores like piranhas and sharks.
Conical teeth that are slender, long, and crowded in indistinct rows, are called villiform teeth. These are typically present in deep-sea fishes but also in fish that swim closer to the surface, like the garpike.
Short and slender conical teeth packed in multiple distinguishable rows are called cardiform teeth. Catfish have cardiform teeth on the roof of their mouths.
Incisors are flattened teeth, usually with a chisel-like shape. Such teeth are not sharp like canines but fulfill a similar purpose. Incisors are good for cutting into food and can inflict damage on prey. They’re almost invariably seen in omnivorous fish.
Sometimes, fish incisors can look disturbingly similar to human teeth. That’s the case for wild fish like the sheepshead or some triggerfish. Luckily, aquarium pet fish don’t fall into this category.
Molars are broad, blunt, and usually short. They’re used for crushing food. If a fish has pharyngeal teeth, these are most commonly molars.
Bottom-dwelling fish that feed on hard-shelled invertebrates like snails and mollusks also have molars. Besides the throat, molars are also typically present on the roof of the mouth and sometimes the lips.
Many aquarium fish that appear toothless typically have pharyngeal molars. Such fish produce a clicking sound when using these teeth to crush food. Common aquarium fish with such teeth include goldfish, loaches, and some cichlids.
Fused plates are exactly what they sound like. They don’t look like teeth at all but are long portions of hard, boney growth. Fused plates are blunt and occur on the upper and lower jaws, right behind the lips.
They can form a beak-type mouth, and their main function is crushing hard-shelled organisms like mollusks or snails. The saltwater parrotfish is an example of a wild species with fused plates. Common aquarium pets like pufferfish also sport these teeth.
The word “tongue” is a misnomer, as I’ll explain in the following sections. But since we’re discussing the inner mouth anatomy, I’m going to cover this here in short.
Fish, like most animals, have a basic organ that covers the floor of the mouth. When you peek inside a fish’s mouth, you’ll see the pink, fleshy interior and a tongue-like flap resting behind the lower teeth. The flap might be smooth or covered in rows of fine teeth.
This flap looks almost identical to what we call a “tongue.” But appearance is the only similarity between these structures.
For all intents and purposes, fish “tongues” are anatomically and functionally different from real tongues.
Do Fish Have an Organ Known as a Tongue?
Fish do have an organ that looks like a tongue, but it doesn’t function like one. A fish’s “tongue” is actually called a “basihyal.” It’s a small flap that sits on the floor of the mouth.
It might be located in the same place and look very similar to a real tongue, but its anatomy and function couldn’t be more different.
Tongues have specific characteristics. They’re a muscular organ with multiple taste receptors and a wide range of motion. Animals primarily use tongues to taste food. The tongue also produces saliva and it aids in chewing and swallowing. A basihyal has none of these characteristics.
Basihyals are bony structures and a direct extension of the fish’s lower inner mouth. Basihyal might be smooth or covered in rows of fine, bristle-like teeth. Since this organ is mostly bone, it’s very inflexible compared to a tongue.
A fish’s basihyal usually lacks taste receptors, so the fish can’t use it to taste food. Instead, the taste receptors are on the inside walls of the mouth, on the lips, or on the outside of their bodies.
The Purpose of Fish Tongues
As we’ve discussed so far, a fish’s basihyal works nothing like a real tongue. What does it do, then? Quite a few things, actually.
Basihyals accomplish many useful functions, including:
Fish “tongues” can’t move in many directions, but they’re good for one thing— they can move backward. They help push the food to the back of the mouth, allowing the fish to swallow its prey.
Holding onto prey
This is especially true for basihyal with teeth. This organ has a limited range of motion but works well for trapping prey.
Fish process oxygen through their gills. But they first take up oxygen-rich water with their mouths. When the basihyal moves backward, it pushes the fresh water through the fish’s gills, completing the breathing cycle.
Protecting the ventral aorta
The ventral aorta is an important blood vessel that transports blood from the heart to the gills. This organ sits next to the floor of the fish’s mouth. It makes sense for fish to have built-in protection for this sensitive organ.
Otherwise, swallowing feisty live prey can prove deadly. That’s where the bony basihyal comes into play. It sits snugly on top of the ventral aorta, shielding it from damage.
The Ability of Fish Tasting Food
Like all other animals, fish rely on their senses to navigate the world. Taste is a crucial bodily sensation that helps fish seek out food. Taste perception also allows fish to pick up on harmful environmental chemicals.
Surprisingly, fish have very complex taste perception. They can taste all basic flavors, including salty, sour, bitter, sweet, and umami (also known as savory). Fish can even taste food from afar before even touching it. How crazy is that? Not very crazy once you learn how fish taste food…
Fish can taste thanks to microscopic sensory organs called “taste buds.” Taste buds communicate directly with the brain. Upon exposure to chemicals, the taste buds fire up and send signals, alerting the brain about how a given food tastes.
And fish have an insane number of tastebuds. Catfish, in particular, have an excellent sense of taste because they can have up to 600,000 tastebuds spread throughout their bodies! For reference, humans have 2,000-8,000 tastebuds in total. You do the math.
But unlike humans and other animals, fish have little to no tastebuds on their tongues. Not to worry though, because their tastebuds abound in multiple other locations, including outside their bodies. That’s how they can taste the food before eating it.
Fish tastebuds have varying numbers of tastebuds scattered in different spots throughout their bodies, including:
- Fins (especially the tail)
- Inner mouth walls
- Upper lip
- Outside of the mouth
- Whiskers (in fish that have them)
Unfortunately, because fish have tastebuds outside their bodies, water quality plays a huge role in their taste perception. Factors like temperature, water pollutants, salinity, and the odor of food can alter their sense of taste and food preferences.
Examples of Fish Species That Have ‘Tongues’
The fish “tongue” or basihyal fulfills essential functions like transporting oxygen and protecting sensitive blood vessels in the fish’s mouth.
Unsurprisingly, most fish have one. Such tongues are present in wild fish and aquarium pets alike.
Here are just some examples:
- Codfish (Gadus genus)
- Salmon (Salmonidae family)
- Anglerfish (Lophiiformes order)
- Clownfish (Amphiprion ocellaris)
- Cichlids (Cichlidae family)
- Goldfish (Carassius auratus)
- Betta fish (Betta trifasciata)
In fact, there’s also an entire order of fish called “Osteoglossiformes,” in which the “tongue” is most noticeable. The scientific name translates to “bony tongues,” which couldn’t be more fitting!
Some fish in this genus include the freshwater butterflyfish (Pantodon buchholzi), spotted knifefish (Chitala ornate), and elephant nose fish (Gnathonemus petersii).
Other aquatic animals, namely invertebrates, don’t have tongues. This applies to starfish, sea urchins, shrimp, crabs, lobsters, snails, and so on.
Fish do have a tongue-like organ called a “basihyal.” However, this structure is anatomically and functionally different from a real tongue.
Fish tongues are made of bone and cartilage, not muscle. Sometimes, they might be covered in teeth, too!
Beyond that, fish tongues have little (if any) taste receptors. So, the basihyal won’t help fish taste food.
This organ’s main functions include transporting food and oxygen through the fish’s body and protecting sensitive blood vessels in the fish’s mouth. Virtually all fish have this organ, whether we’re talking wild fish or aquarium pets.