Do Frogs Have Teeth? Which Frogs Have Them and Which Don't

Where are frog teeth?

If you could look inside the mouth of a typical frog, such as an American bullfrog or a common frog, you would find two kinds of teeth:

• Upper jaw teeth (maxillary and premaxillary teeth): a single row of very small, pointed teeth along the edge of the upper jaw. Run a finger along it and it feels like fine sandpaper.
• Vomerine teeth: two small clusters on the roof of the mouth, on bones called the vomers, just behind the nostrils’ inner openings.

The lower jaw is usually smooth, with no teeth at all. This is one of the features that define modern frogs, and it has been true for most frogs for more than 200 million years.

Frog teeth are tiny and often hard to see. In many species they are only a fraction of a millimeter long. Like other amphibians, frogs replace worn teeth with new ones throughout their lives.

What do frogs use their teeth for?

Frogs do not chew. Their teeth act like a grip strip, helping them hold on to wriggling insects, worms, fish or other frogs while they swallow. The real catching tool is the tongue, which in most frogs is attached at the front of the mouth and can be flipped out with sticky saliva to snag prey.

Swallowing uses a surprising helper: the eyes. Frogs have no bony floor beneath their eye sockets, so they can pull their eyeballs down into the head. As the eyes sink, they press on the roof of the mouth and help push food toward the throat, which is why a frog seems to blink hard when it swallows. More on this in What do bullfrogs eat?

Which frogs have no teeth?

Not all frogs have teeth. A 2021 study of hundreds of species found that frogs have lost their teeth completely more than 20 times during their evolution, more than any other group of vertebrates studied.

The best-known toothless group is the true toads (family Bufonidae), which include the common toad of Europe, the American toad and the cane toad. These animals have no teeth in either jaw. This is one of several differences between frogs and toads, compared in frog vs toad.

Toothlessness has also appeared in many other lineages, including some narrow-mouthed frogs and other species that specialize in eating tiny prey such as ants and termites. Scientists think teeth are less useful when a frog eats lots of very small insects that can be swallowed instantly, and more useful for frogs that tackle large, struggling prey.

The only frog with true teeth on both jaws

One South American frog breaks the rule. Guenther’s marsupial frog (Gastrotheca guentheri), from the Andes of Colombia and Ecuador, has true teeth in its lower jaw as well as its upper jaw. It is the only living frog known to have them.

What makes this remarkable is that the frog’s ancestors had lost their lower teeth more than 200 million years earlier. A 2011 study concluded that lower teeth evolved again in this species, which challenges the old idea, called Dollo’s law, that complex features cannot reappear once lost. Sadly, the species has not been seen in Ecuador since the 1990s, and its status in Colombia is uncertain.

Fangs that aren’t teeth

Some frogs have spikes that look like fangs but are not true teeth. These are bony projections of the lower jawbone, called odontoids.

• The African bullfrog (Pyxicephalus adspersus), which eats mice, frogs and even small snakes, has sharp, tooth-like points at the front of its lower jaw.
• The fanged frogs (Limnonectes) of Southeast Asia have large, tusk-like odontoids in the lower jaw, which males in some species use when fighting.
• Horned frogs (Ceratophrys) of South America combine true upper teeth with sharp lower odontoids and can grip large prey firmly.

These species can bite hard, which is one reason people are advised to leave large wild frogs alone.

Tadpole “teeth”

Tadpoles have mouthparts of their own. Most tadpoles have a horny beak surrounded by several rows of tiny, hard keratin structures, sometimes called labial teeth or keradonts. They are made of the same kind of material as fingernails, not bone or enamel, and are used to scrape algae from rocks and plants.

At metamorphosis these structures are shed. The young frog’s skull and jaw are rebuilt, and in most species true teeth then develop on the upper jaw.

Myths and facts about frog teeth

Myth: Frogs have no teeth. Most frogs do have teeth, though they are tiny and hidden.

Myth: Frogs chew their food. No frog chews; all swallow their prey whole.

Fact: Frogs and toads can differ in teeth. Many frogs have upper teeth, while true toads have none, so checking for teeth is one way experts tell some groups apart.