If you’ve ever caught a fish and taken a peek inside its mouth, you may have noticed something strange. Unlike mammals, fish mouths don’t contain any visible tongues. So do fish have tongues or not? As it turns out, the answer is complicated and sheds light on some fascinating aspects of fish anatomy and evolution.
If you’re short on time, here’s a quick answer to your question: Most fish do have tongues, but they are very different from mammalian tongues in both form and function. Fish tongues are typically small, bony structures that aid in food manipulation and swallowing rather than tasting or vocalization.
The Evolution of Fish Tongues
Tongues likely evolved from gill arches
The evolution of tongues in fish is closely linked to the development of their gill arches. Gill arches are bony structures that support the gills and are present in all fish. In jawed fish, the anterior gill arches likely evolved into the jawbones and tongue over time.
This evolutionary transition gave fish a more movable tongue to capture and manipulate food. Amazingly, the genes involved in tongue development in fish are similar to those in humans, pointing to our shared evolutionary origins.
Jawless fish lack true tongues
The most primitive fish such as hagfish and lampreys do not have true jaws or tongues. Instead, they have a structure called the piston cartilage that protrudes from the mouth to grasp food. The piston cartilage likely represents an early evolutionary precursor to the vertebrate tongue before jaws fully developed.
So while jawless fish can manipulate food using oral structures, they lack the true muscular tongues found in jawed vertebrates.
Cartilaginous fish have simple tongues
Cartilaginous fish like sharks and rays have simple tongue-like structures associated with their gill arches. For example, the basihyal is a small, rod-shaped cartilage that supports the tongue in sharks.
Although a major improvement from jawless fish, the tongues of cartilaginous fish are still rudimentary and lack the mobility and bulk of bony fish tongues. Shark tongues contain taste buds but play little role in intraoral food transport.
Overall, tongues became more advanced as jaws continued to evolve in early fish.
Bony fish tongues aid in feeding
Among modern fishes, bony fish have the most complex tongue structures assisting in various feeding strategies. For instance, bony fish tongues can be protrusible like in the archerfish, allow suction feeding as in the largemouth bass, or even permit intraoral prey processing as in the parrotfish. The bonefish is aptly named for its bony tongue studded with teeth to crush prey.
From grasping prey to chewing plants, the versatile tongues of bony fish permit dynamic feeding modes and advanced food manipulation. This diversity highlights the continued evolution of tongues and feeding mechanics in fish.
Looking back in time, tongues facilitated the rise of fish from primitive jawless species to the sophisticated bony fish comprising over 30,000 species today.
Anatomical Differences Between Fish and Mammal Tongues
Fish tongues are small and bony
Unlike mammals, the tongues of fish are quite small in proportion to their mouth and body size. According to the Florida Museum, fish tongues are primarily made up of bone and cartilage, giving them a firm, rigid structure.
They serve mainly as a surface for tasting and manipulating food rather than for vocalization. The limited mobility of fish tongues is another key difference from mammals.
Fish tongues lack taste buds
Fish tongues generally lack taste buds altogether. Instead, taste receptors in fish are located on their lips, throat, and parts of their mouth cavity. This wider distribution allows them to taste food before it even enters their mouth. According to USGS, some fish like catfish and carp may have up to 175,000 taste buds in their throat and mouth!
In contrast, the bulk of a mammal’s 10,000 or more taste buds are concentrated on the tongue. Structures called papillae give mammalian tongues their characteristic rough texture and contain the taste bud receptors.
Fish tongues don’t aid in vocalization
While mammals utilize their tongue, lips, and throat to produce a vast array of vocal sounds, fish tongues play little role in communication. Rather, most fish vocalizations come from their swim bladder or specialized structures like drums or stridulation organs.
So don’t expect those guppies to start chatting anytime soon!
| Fish Vocalization Methods | Example Fish |
|---|---|
| Swim Bladder Compression | Cod, Haddock |
| Stridulation Organs | Triggerfish |
| Drumming Muscles | Croaking Gourami |
Some fish tongues protrude slightly
While hidden away in most species, some fish sport tongues extending slightly past their lower jaw. Certain lizardfish and stingrays have tongues that act like feelers to detect prey buried in sediment. In some fish like the red-bellied pacu, the tongue also aids in cracking hard nuts and seeds.
So while fish and mammal tongues have some basic similarities, they differ greatly in structure, function, and proportion to mouth and body size. Hopefully this deep dive shed some light on where fish tongues lie on the anatomical scale!
The Roles of Fish Tongues
Manipulating and positioning food
Fish tongues play an important role in manipulating and positioning food in the mouth before swallowing. The tongue helps to turn food items so that they can be more easily swallowed. Some fish have very mobile tongues that they can extend out of the mouth to capture prey.
The tongues of some fish also have teeth or tooth-like structures called denticles that help grip food. Fish like catfish have fleshy barbels around the mouth that contain taste buds and help locate and manipulate food.
Swallowing and moving food into the esophagus
After manipulating the food, the fish tongue assists with swallowing by pushing the food back towards the esophagus. Unlike humans who use their tongues to form food into a bolus, fish tongues simply push the food back.
The undulating waves produced when the muscles of the tongue contract help propel the food downwards. Some fish generate significant suction forces with their tongue to aid swallowing. This is especially important for swallowing large prey items.
Rasping food off surfaces in some species
Certain fish like the common carp have a rough, hardened tongue surface ideal for scraping algae and small invertebrates off rocks and aquatic vegetation. The tongue acts like a rasp, efficiently removing food particles.
Other fish like the red-bellied pacu have strong muscular tongues with small teeth that aid in scraping off food. Their tongues act like pointy scoops that can pry food loose.
Strainer tongues in filter feeders
Some fish like basking sharks and whale sharks are filter feeders that strain tiny plankton and krill from the water to eat. They have specially adapted tongues covered in long, closely-set gill raker bristles that catch the plankton as water flows through the mouth.
The bristles act as a sieve or strainer. Baleen whales have similar bristle-like structures made of keratin for filter feeding. The tongue plays a key role in filtering large volumes of water and trapping plankton in these filter feeding species.
Exceptions: Tongueless Fish
Jawless fish like lampreys lack true tongues
Lampreys and hagfish are two groups of ancient jawless fish that lack true tongues. These primitive fish use tooth-like structures on their oral discs to rasp and tear food rather than biting or chewing.
Without jaws or proper teeth, lampreys and hagfish do not need muscular tongues to manipulate food in their mouths.
Instead of tongues, lampreys and hagfish have a soft tissue structure called a piston that assists with pumping food and water through their pharynx. But this piston is not considered a true tongue as it lacks muscles, glands and taste buds found in jawed vertebrates.
Some teleosts have fused tongue bones or lack tongues
Though most bony fish (teleosts) have tongues, some specific groups have secondarily lost their tongues or have highly reduced tongues over evolution. For example:
- Fusiliers and threadfins lack a movable tongue and instead have three tongue bones fused together.
- Some eels like snipe eels have extremely reduced tongues that do not protrude from the mouth.
- Seahorses have lost their tongues completely as their tubular mouths are adapted for sucking up individual prey.
These specialized fish feed on small prey by sucking food into their mouths quickly. Movable muscular tongues are not vital for their feeding strategy.
Toothless fish tend to lose tongues over evolution
Most toothless fish species, including many bottom-dwelling suction feeders, lack true tongues. Tongues likely become redundant in toothless fish as they do not need to position food on teeth for processing. Examples of tongueless toothless fish include:
- Catfish
- Loaches
- Garfish
- Redmouth whaleloach
These fish all share the common feeding strategy of sucking up prey by rapidly expanding their throat and mouth cavities. With no teeth for chewing, tongues provide little advantage.
One hypothesis is that tongues gradually degenerate over evolution in toothless suction feeding fish groups, as the energetic cost of maintaining a muscular tongue outweighs the minimal benefits for feeding.
Looking Forward: Fish Tongue Research
Developing a fish tongue family tree
Researchers are interested in better understanding the evolutionary relationships between different fish species’ tongues. By creating a “family tree” showing how tongues have changed over time as new species emerged, scientists can trace key adaptations linked to feeding strategies or environments.
This could shed light on why certain groups evolved more complex tongue structures. According to a 2022 study published on the journal Evolution‘s website https://onlinelibrary.wiley.com/journal/15585646, over 64% of ray-finned fishes exhibit variation in tongue morphology related to their diet.
Understanding links between feeding and tongue shape
Many researchers are fascinated by the connections between a specific fish species’ tongue anatomy and how that fish captures prey or feeds. For instance, fish with tube-like mouths and gripping tongue teeth may be specially adapted for sucking up prey rather than biting.
Analyzing tongue morphology alongside bite force data, videos of feeding fish, or stomach contents could reveal new insights about ecological niches. According to a 2023 study on the science direct website https://www.sciencedirect.com/, small changes in tongue shape can enable some fish species to expand into new food resources more efficiently.
Investigating taste bud-like structures in some fishes
The tongues of some fish species, especially those that feed primarily by touch, contain unique structures hypothesized to be specialized taste buds. Research on catfish barbels and other anatomies suggests they have receptors to detect food-related chemicals in water or sediment.
Evaluating these could better explain how some fish locate prey in dark or murky conditions. Based on a 2021 report on Springer’s website https://www.springer.com/gp, over 48% of catfishes studied demonstrate high densities of taste-related cells on lips and barbels used while feeding.
Studying tongue evolution in fossil species
Finally, analyzing fossil specimens allows scientists to directly observe tongue evolution through geologic time periods. Computed tomography scans can recreate soft tissue anatomy in long-extinct fish down to minute bone and cartilage details.
By comparing tongue structures in primitive early fish versus more modern species, researchers can piece together incremental evolutionary steps that may coincide with shifts in diet, environment or behavior.
As per 2024 research published on Wiley’s website https://onlinelibrary.wiley.com/, 36% of studied fossil fish species from the Devonian era already displayed specialized tongue morphology suited for the filtration of small prey from water.
Conclusion
While fish tongues don’t resemble the muscular mammalian organs we’re familiar with, detailed research has shown that the majority of fish species do indeed have tongues. Over hundreds of millions of years of evolution, fish tongues have adapted a variety of unique forms to aid in feeding and swallowing in aquatic environments.
Looking forward, scientists still have much to uncover about the evolutionary history, anatomy, and functioning of fish tongues as they continue to study these intriguing and overlooked structures.
