Do Anteaters Have Teeth? How They Eat Without Them

Anteaters have no teeth at all, and they haven’t for a very long time. The lineage lost the ability to form functional teeth somewhere between 55 and 65 million years ago, making anteaters one of the most thoroughly toothless groups of mammals on the planet. All four living species, the giant anteater, the silky anteater, and two species of tamandua, share this trait, as do all known fossil relatives. Yet they thrive on a diet of ants and termites, processing tens of thousands of hard-shelled insects a day using a suite of adaptations that make chewing irrelevant.

Ghost Teeth That Vanish Before Birth

One of the stranger details about anteaters is that their embryos actually start growing teeth. Tooth buds, the earliest stage of tooth formation, appear during development in pygmy anteaters and have been documented in other anteater species as well.¹ These rudimentary tooth germs never mature. They are resorbed before birth, so no anteater is ever born with anything resembling a tooth.²

This is a hallmark of evolutionary loss. The genetic instructions for the earliest steps of tooth development persist, even though the later stages have been disabled. It tells researchers that anteater ancestors unquestionably had teeth and that the initial molecular signals for building them haven’t fully decayed, even after tens of millions of years. The process is a bit like finding the foundation of a demolished building: you can see where the structure was planned, even though nothing was ever completed.

Genetic work has pinpointed part of how the loss happened. The gene for enamelin, a protein critical for forming tooth enamel, accumulated several frame-disrupting mutations on the branch leading to all anteaters and sloths. Those mutations occurred after this group split from armadillos roughly 65 million years ago but before sloths and anteaters diverged from each other around 55 million years ago.³ That means the pathway to enamel-coated teeth was already broken in the common ancestor of anteaters and sloths. Sloths went on to evolve their own style of simplified, enamel-free teeth, while anteaters abandoned teeth entirely.

A Tongue Built for Speed

Without teeth, the tongue does all the work of food acquisition. A giant anteater’s tongue can extend beyond the length of its own skull, and the animal flicks it in and out of an insect mound with startling speed.⁴ Estimates of the protrusion-retraction cycle vary, but it happens fast enough that the tongue can be darted in and out of a nest many times per minute, scooping up insects with each pass.

The tongue is coated in thick, sticky saliva that traps ants and termites on contact. That stickiness isn’t incidental. The mandibular salivary gland in the giant anteater is unusually large and produces saliva loaded with complex glycoproteins, molecules with elaborate sugar chains attached. A channel-forming protein called aquaporin 5 helps regulate how viscous the saliva is, keeping it at the right consistency for insect capture.⁵ In effect, the saliva functions as living flypaper, and the tongue is the delivery mechanism.

The tongue’s reach is powered by a specialized arrangement of hyoid muscles, the muscles anchored to the small bone at the base of the tongue. In most mammals, these muscles help with swallowing. In anteaters, they’ve been repurposed to launch and retract the tongue at high speed with precise control over where it goes. The tongue can be projected even without the mouth opening very wide, which matters when you’re feeding through a small hole punched into a termite mound.⁴

Jaws That Twist Instead of Chew

Anteaters don’t chew their food. They can’t. Their jaws are long, narrow, and tubular, shaped more like a pipe than a traditional mammalian jaw. The mouth opening is tiny, reaching maximum gape at just a few degrees of depression, though the extreme length of the snout stretches that small gape to roughly two centimeters.⁴ That’s enough for the tongue to dart out, but not enough for conventional biting.

Instead of moving up and down, the mandibles rotate inward and outward. This twisting motion reshapes the oral cavity, expanding it to give the tongue room to retract loaded with insects, then narrowing it to help scrape the catch off the tongue. Three-dimensional imaging has shown that the shape and volume of the mouth change dramatically during this rotation.⁶ The muscles responsible are the temporal and pterygoid muscles, which in most mammals power the bite. In anteaters, they’ve been retooled to drive the rotational movement instead.

Several structural features of the skull support this unusual motion. The mandibular ramus, the upward projection at the back of the lower jaw where chewing muscles usually attach, is unusually low. The zygomatic arch, the bony bar along the side of the skull that in most mammals serves as an anchor for powerful jaw-closing muscles, is incomplete. Both features reduce interference during the twisting motion and redirect the force inward rather than upward.⁶ The whole system is optimized for speed over force: the muscles are smaller but move the jaw over shorter distances, faster, complementing the rapid tongue cycle.

How Anteaters Actually Digest Insect Armor

Since nothing is chewed, insects arrive in the stomach largely intact, still wearing their exoskeletons. Insect exoskeletons are made of chitin, a tough structural carbohydrate that most mammals can’t break down efficiently. Anteaters have evolved a multi-layered approach to the problem.

The first layer is enzymatic. Anteaters produce acidic mammalian chitinase, an enzyme that attacks chitin directly. Where many mammals carry only one or two functional copies of the gene encoding this enzyme, the lesser anteater (southern tamandua) has four functional copies. Each copy is expressed at high levels in different parts of the digestive system: the salivary glands, stomach, liver, and pancreas all contribute to chitin breakdown using different versions of the enzyme.⁷ Having multiple copies working simultaneously at different points along the digestive tract means chitin gets hit from multiple angles, increasing the total capacity to break it down.⁸

The second layer involves the gut microbiome. Researchers who sequenced bacterial genomes from the guts of several ant-eating mammal species found chitin-degrading enzymes scattered across hundreds of bacterial genomes recovered from the intestines.⁹ The bacteria appear to pick up where the animal’s own enzymes leave off, continuing to break down chitin fragments in the lower gut. Clostridial bacteria isolated from anteater intestines can grow on chitin as a substrate, confirming they use it as a food source and likely release nutrients the anteater can then absorb.¹⁰

There’s also a physical component. The muscular stomach grinds food mechanically, taking over the role that teeth play in other mammals. Anteaters sometimes swallow small amounts of soil and sand along with their insect meals. The stomach contents of wild giant anteaters tend to be unusually high in ash and certain minerals compared to the insects themselves, suggesting incidental soil ingestion is common.¹¹ Whether the grit aids digestion the way it does in birds that use gizzard stones isn’t settled, but the muscular stomach is clearly the primary site of physical breakdown.

Nerve Channels Where Teeth Used to Be

Even though anteaters haven’t had teeth for tens of millions of years, their jawbones still carry traces of the old dental infrastructure. In most toothed mammals, the mandibular canal runs through the lower jaw carrying nerves and blood vessels to each tooth. In anteaters, this canal has been extensively remodeled but not eliminated. More surprisingly, researchers found small channels called dorsal canaliculi branching upward from the canal to the surface of the jaw, opening in tiny holes along the upper edge where a dental pad sits.¹²

All three anteater species that were examined had these channels, positioned consistently along the jaw with only minor variation between individuals and between the left and right sides. The researchers who described them proposed that the channels carry sensory nerves to the dental pad, giving the anteater tactile feedback during feeding. When your tongue is shuttling insects through a narrow tube-shaped mouth dozens of times a minute, being able to sense what’s on the tongue surface could matter for efficiency. Pangolins, which also eat ants and termites and also lack teeth, don’t have this feature, so it’s not a universal consequence of losing teeth. It appears to be something specific to how anteaters repurposed their jaws after teeth disappeared.¹²

Pangolins Solved the Same Problem Differently

Pangolins are the animal most often compared to anteaters, and for good reason: they eat the same food, lack teeth, and have long sticky tongues. But the two groups are not closely related. Anteaters are xenarthrans, native to the Americas and related to sloths and armadillos. Pangolins are their own order, found in Africa and Asia. Their similarities are a textbook case of convergent evolution, where unrelated lineages arrive at similar body plans because they face similar ecological pressures.

The convergence is striking on the surface but falls apart in the details. Anteaters have four functional copies of the chitinase gene and have lost a fifth; pangolins have lost all but one and rely heavily on that single remaining copy, which is expressed at extremely high levels in the stomach and salivary glands to compensate.⁷ So both groups can digest chitin, but they arrived at the ability through opposite genetic strategies: anteaters kept and duplicated multiple genes, while pangolins cranked up the expression of a single surviving one.

The jaw sensory system also differs. Anteaters retained and repurposed nerve channels from their toothed ancestors to serve the dental pad. Pangolins lack those channels entirely.¹² Whatever sensory feedback pangolins use while feeding, it doesn’t come from the same anatomical source. Studies looking at whether these ant-eating mammals evolved enhanced senses of smell to locate their prey have also come up empty. A comparison of the nasal structures across several ant-eating lineages found no consistent evidence of increased olfactory capacity compared to their closest non-ant-eating relatives, despite the elongated snouts that look like they’d be great for sniffing things out.¹³ The long snout, it turns out, is primarily about getting the tongue into tight spaces, not about improving the nose.

Their Closest Relatives Have the Strangest Teeth in Mammalia

Anteaters belong to the superorder Xenarthra, alongside sloths and armadillos. The name “Xenarthra” refers to the extra joints in their vertebrae, but they could just as fairly be named for their bizarre dental situation. Armadillos and sloths do have teeth, but those teeth are deeply weird by mammal standards.

Most mammals have teeth differentiated into incisors, canines, premolars, and molars, each coated in enamel and patterned with cusps that reflect diet and ancestry. Xenarthran teeth violate almost every one of those rules. They are ever-growing, meaning they continue to erupt throughout life rather than forming a fixed adult set. They lack enamel entirely. Instead of the usual layered structure of enamel over dentine, their teeth are composed of a modified tissue called osteodentine. The cusps and ridges seen on the teeth of other mammals are absent. The teeth tend to be reduced in number and size, often separated by gaps, and generally look like simple pegs or cylinders.¹⁴

Armadillos use these simplified teeth to process a varied diet that includes insects, small vertebrates, and plant matter, managing fine despite the lack of enamel. Sloths grind leaves with their ever-growing pegs. Anteaters took the trend of dental simplification to its logical extreme: rather than maintaining teeth with increasingly reduced function, they eliminated them and let the tongue, saliva, and stomach take over entirely. It’s worth noting that the genetic foundation for this loss, the disabling of the enamelin gene, was already in place in the ancestor anteaters shared with sloths.³ Sloths found a workaround by building teeth from osteodentine instead of enamel. Anteaters simply stopped building teeth at all.

The Energy Budget of Eating Without Chewing

A diet of tiny insects eaten one sticky tongue-flick at a time might seem energetically wasteful, and in some respects it is. Anteaters tend to have low metabolic rates compared to similarly sized mammals, which helps balance the low energy density of their food. Studies on the silky anteater, the smallest species at around 200 grams, have measured how much energy wild individuals spend daily and how much food that requires. Researchers calculated that the ant diet consumed by silky anteaters is roughly three-quarters water by weight, and that the digestible dry matter in ants provides about 23 kilojoules per gram.¹⁵ That means an anteater has to process a large volume of watery, chitinous food to extract a modest amount of energy.

Giant anteaters compensate by visiting many nests in a single foraging bout, spending only a minute or two at each one before moving on. This hit-and-run strategy avoids depleting any single colony, which ensures the food source regenerates, and also minimizes the risk of being swarmed by soldier termites or stinging ants. The rapid tongue cycle, the rotational jaw mechanics, and the sticky saliva all work together to maximize intake per second at each nest. The whole feeding apparatus is optimized not for thorough processing of each mouthful but for volume and speed: get as many insects onto the tongue and into the stomach as quickly as possible, and let the enzymes, acid, and gut bacteria handle the rest.

Captive anteaters fed commercial insectivore diets face a different set of challenges. The commercial diets tend to have much higher calcium and phosphorus levels than the insects and soil that wild anteaters consume.¹¹ These nutritional mismatches are a real concern in zoo husbandry. Captive giant anteaters have historically suffered from health problems that may be linked to diets that poorly approximate the mineral and macronutrient profile of what they’d eat in the wild. Getting the diet right for an animal that evolved to lick up thousands of ants coated in dirt, process them with specialized enzymes, and grind them in a muscular stomach is, unsurprisingly, difficult to replicate with manufactured food.

1
Current Biology. Mandibular Canal Remodeling in Toothless Placental Mammals
2
PubMed Central. Loss of teeth and enamel in tetrapods: fossil record, genetic data and morphological adaptations
3
PLOS Genetics. Molecular Decay of the Tooth Gene Enamelin (ENAM) Mirrors the Loss of Enamel in the Fossil Record of Placental Mammals
4
Journal of Zoology. Morphology, evolution and function of feeding in the giant anteater (Myrmecophaga tridactyla)
5
PubMed. Morphology, glicohistochemistry and immunolocalization of Aquaporin 5 in the mandibular gland of the giant anteater (Myrmecophaga tridactyla)
6
Zoological Science. Three-Dimensional CT Examination of the Mastication System in the Giant Anteater
7
PubMed Central. Transcriptomic Data Reveal Divergent Paths of Chitinase Evolution Underlying Dietary Convergence in Anteaters and Pangolins
8
National Science Review. Hologenomic insights into mammalian adaptations to myrmecophagy
9
PubMed Central. Metagenomics uncovers dietary adaptations for chitin digestion in the gut microbiota of convergent myrmecophagous mammals
10
Frontiers in Veterinary Science. Metabolic diversity and responses of anteater clostridial isolates to chitin-based substrates
11
PubMed Central. Comparison of Estimated Wild Giant Anteater Diets with Commercial Diets for Insectivores: Implications for Anteater Health
12
Current Biology. Dental Innervation Structures Preserved in Toothless Anteaters Provide Evidence of a Sensory Role
13
Wiley Online Library (The Anatomical Record). Sniffing out morphological convergence in the turbinal complex of myrmecophagous placentals
14
Cambridge University Press. The teeth of the “toothless”: novelties and key innovations in the evolution of xenarthrans (Mammalia, Xenarthra)
15
Edentata. Field Metabolic Rate, Water Flux and Food Consumption by Free-Living Silky Anteaters (Cyclopes didactylus) in Panama