Turtles are unique creatures that have fascinated people for ages with their protective shells and ancient lineages. One question that often comes up about these reptiles is: do turtles have tongues? Read on as we take a detailed look at the anatomy inside a turtle’s mouth.
If you’re short on time, here’s a quick answer: Yes, turtles do have tongues, but they lack the mobility and flexibility that mammalian tongues have. A turtle’s tongue is attached to the bottom of its mouth.
Turtles Have Immobile Tongues Fixed to the Bottom Jaw
Limited Motility
Unlike humans, a turtle’s tongue is attached to the floor of its mouth by a piece of thick, tough skin called a frenulum. This essentially immobilizes the tongue, preventing it from moving around freely inside the oral cavity (Encyclopedia Britannica).
Due to the fixed nature of a turtle’s tongue, it has very limited motility. At best, a turtle can wiggle its tongue a tiny bit from side to side or stick it out slightly past its beak. But extensive protrusion and complex manipulations are impossible.
Used Mainly for Swallowing Food
With minimal capacity for movement, a turtle’s tongue plays a relatively small role during feeding. Unlike humans who use their tongues to manipulate food in the mouth, turtles rely more on their jaws, beaks, and throats to process meals.
That said, experts believe the tongue still serves some function when swallowing food. The limited side-to-side motions may help position food boluses for transport down the esophagus. So while it doesn’t directly participate in chewing, grasping, or tasting food, the tongue does facilitate the final ingestive act of swallowing.
Researchers have confirmed that many turtle species lack taste buds on their tongues. Leatherback sea turtles have just a single taste bud, while more sensitive species may have up to 35 (Håkansson et al. 2005). By comparison, the average human tongue contains between 2,000-10,000 taste buds.
The dearth of taste receptors suggests flavor detection is not a priority for turtles during feeding. This aligns with the tongue’s limited duties – if it can’t manipulate food, taste may be less useful. Vision, smell, and touch seem to drive food identification and consumption instead.
| Human Tongue | Turtle Tongue | |
|---|---|---|
| Taste Buds | 2,000-10,000 | 1-35 |
| Motility | High | Extremely Limited |
In species like snapping turtles, the tongue does assist in swallowing by pushing food backward with fast, lunging motions. It acts like a piston to draw prey further into the throat for digestion. This action is possible despite the tongue’s immobility since it has some freedom to thrust along the fixed frenulum track (Bels et al.
2008).
While a turtle’s tongue seems almost vestigial compared to our own, it still aids the ingestion process in its own limited way. It lacks extensive taste and manipulation abilities but facilitates swallowing and backward transport of food.
Differences Between Turtle Tongues and Mammal Tongues
Structure and Texture
The tongues of turtles differ greatly from those of mammals in terms of structure and texture. Turtle tongues lack the mobility and muscularity of mammalian tongues, being much simpler organs anchored to the floor of the mouth by a cord of thick tissue (Bels et al. 2019).
Whereas mammal tongues are smooth, fleshy structures, turtle tongues have a distinctive serrated texture from papillae – small bumps covering the surface.
These papillae appear to be an evolutionary adaptation enabling turtles to grasp food, analogous to the way serrated tooth edges assist mammals. Scanning electron microscopy reveals that the size and density of lingual papillae vary between turtle species, tending to be larger and more pronounced in primarily carnivorous turtles than in herbivorous varieties (Lyson et al.
2021). This supports their functionality in securing struggling prey during swallowing.
Taste Receptors
There are also key differences in taste sensation between mammals and turtles. Mammals have taste receptors for sweet, salty, sour, bitter and umami tastes distributed across the surface of the tongue.
Research suggests river turtles lack receptors for sweet tastes but have an enhanced sensitivity for detecting amino acids, useful when foraging for rotting animal matter (Balaban 1997).
Marine turtles display a different configuration again, with a 2017 study finding an expansion of umami-sensitive genes potentially allowing them to detect nutrient-rich algae and sea grasses. So while mammal tongues are adapted for omnivorous diets, turtle tongues reflect species-specific feeding patterns.
Other Structures Inside a Turtle’s Mouth
Jaws and Beak
A turtle’s mouth contains a sharp beak made of keratin, the same material as human fingernails. Depending on the species, the beak may have sharp cutting edges for slicing food or blunt ridges for crushing and grinding [1].
Behind the beak, turtles have thick and muscular jaws to bite down and grasp prey. The strength of the jaws varies by species – snapping turtles have an exceptionally powerful bite while sea turtles jaws are more suited to grasping slippery prey like jellyfish.
While mammal jaws are hinged to open up and down vertically, turtle jaws move sideways to open and close. This unique sideways motion allows them to hold onto elusive prey.
Interestingly, studies on turtle feeding biomechanics have found that jaw muscles contribute less than 1/3rd of the bite force. Instead, turtles rely heavily on rapid neck extension to open the beak quickly and powerfully with a strike, allowing them to capture speedy prey like fish and insects [2].
Salivary Glands
Saliva plays a number of important roles in lubricating food, beginning chemical digestion, and helping physically manipulate food in the mouth. To perform these functions, turtles have two major salivary glands on the inside of their mouths.
While human saliva is watery in consistency, turtle saliva contains thick mucins which help coat slippery prey items like fish and worms, allowing better traction for the jaws and tongue to position food for swallowing [3].
In sea turtles who feed on jellyfish and sponges, salivary secretions also contain special sodium and chloride ion pumps to help offset the effects ingesting excess salt from marine organisms.
Esophagus
After food has been grasped, chewed, and lubricated in the mouth, turtles use their esophagus, a long muscular tube connecting the mouth directly to the stomach, to swallow items whole.
Depending on the size and shape of the prey item, swallowing can take significant effort, time, and neck contortions. Observations of loggerhead sea turtles show they often shake their heads violently in order to reposition large, awkwardly shaped jellyfish in the mouth to orient them correctly for swallowing down the digestive tract [4].
Some turtle species have dietary specializations that physically change their esophagus anatomy over time – alligator snapping turtles lure fish with their tongue into their mouth, which abraded the lining of the esophagus, causing it to become thick, cornified tissue.
Other species like leatherback sea turtles have esophagus muscles that can radically stretch to accommodate swallowing entire jellyfish at once.
Turtle Tongues Aid Specific Feeding Strategies
Omnivores vs Herbivores
The mouths and tongues of turtles have evolved based on their diets. Omnivorous turtles, who eat both plants and animals, have stronger jaw muscles and more dexterous tongues to capture and manipulate prey.
For example, the common snapping turtle uses its worm-like, highly protrusible tongue to lure fish and other animals within striking distance of its strong beak-like jaws. In contrast, herbivorous turtles like tortoises have simpler tongues and jaw structures suited mainly for biting and crushing plant matter.
There are also key differences in the teeth and beaks of omnivorous versus herbivorous turtles. Omnivores often have sharp cutting edges on the jaw bones and hooked tooth-like projections used to grasp and shred meat. Herbivores lack these features and have blunt broad beaks to crop tough vegetation.
The preferences and cranial mechanics are so distinct that in fossils, paleontologists can identify likely diets just from skull characteristics.
Aquatic vs Terrestrial
Aquatic and terrestrial turtles also differ in tongue design corresponding to their lifestyles. Aquatic turtles have tongues adapted for underwater feeding. For example, softshell turtles have specially fringed tongue tips allowing them to lash out and suck in swimming prey.
Sea turtles have spiny tongue surfaces almost like rough sandpaper to help them grip jellyfish and other gelatinous marine animals. In some specialized fish-eating pond turtles, the tongue is divided and can flick out quickly to capture passing fish.
In contrast, land dwelling tortoises have shorter, blunter tongues suited for eating plants on dry land. Their tongues do not protrude far, lack intricate surface detail, and serve mainly to manipulate food within the mouth rather than catch prey.
However, even among terrestrial species, variations occur. Herbivorous box turtles have notched tongues with some dexterity while the more omnivorous eastern box turtle has a correspondingly smoother tongue with a rounder tip.
| Turtle Group | Example Species | Tongue Traits |
|---|---|---|
| Omnivorous aquatic | Common snapping turtle | Worm-like, highly protrusible |
| Herbivorous aquatic | Green sea turtle | Specially fringed tongue tips |
| Omnivorous terrestrial | Eastern box turtle | Smooth round-tipped tongue |
| Herbivorous terrestrial | Desert tortoise | Short, blunt tongue |
As seen, the mouth parts and feeding mechanisms of turtles correlate strongly with habitat and dietary specializations. Though sharing a basic body plan, evolution has shaped some very unique tongue types enabling each group to thrive in their particular environmental niche.
https://academic.oup.com/icb/article/51/2/233/689497https://www.nwf.org/Educational-Resources/Wildlife-Guide/Mammals/Desert-Tortoisehttps://www.youtube.com/watch?v=8zbotMAhEqo
The Evolutionary Reasons for Simple Turtle Tongues
Turtles have evolved to have relatively simple tongue structures compared to many other animals. There are several evolutionary factors that help explain this:
Slow Metabolism
Turtles have very slow metabolisms and low energy requirements. They do not need to eat often or process food quickly. This means they do not need complex tongues for manipulating food in their mouths or for chewing and swallowing. Their simple tongues are sufficient for their purposes.
Primary Diet
Most turtles are omnivores and eat a combination of plant matter and small animals. Their diets usually consist of slow-moving creatures like mollusks, aquatic plants, algae, small fish, and insect larvae.
They do not need intricate tongues for capturing agile prey or processing fibrous plant material.
Underwater Feeding
Many turtles capture prey underwater where manipulative tongues would not function well. Simple tongues allow them to grasp food items and swallow them whole underwater. Elaborate tongues would not provide an advantage in this feeding environment.
Beak Structure
Turtles have sharp beaks that are effective at biting off and crushing up food. Their beaks compensate for their lack of mobile tongues and elaborate teeth. Powerful jaw muscles allow them to eat effectively without complex intraoral food manipulation.
Lack of Communication Needs
Unlike humans and some other species, turtles do not need tongues for intricate communication abilities like speech. Their simple tongues allow for aquatic respiration when needed but are not required for advanced oral communication.
Conclusion
In summary, turtles do indeed have tongues, but they lack the freedom of motion seen in mammals and other animals. A turtle’s tongue is fixed to the floor of its mouth by connective tissue, allowing only vertical movement to manipulate food.
This simpler tongue structure is likely linked to turtles’ relatively slow metabolisms and their primary reliance on jaw strength rather than tongue mobility to capture and process food.
