The ancestors of frogs and toads were armed with large fangs and thousands of hook-like denticles, making their modern counterparts look a bit gummy by comparison. Do frogs have teeth? Yes, but exactly what kind of teeth and where they’re found varies significantly.
Frogs have a complex history with teeth, estimated to have lost them over 20 times during their evolution. The uses for teeth among frogs today range from hunting to juicy-lipped love bites, but frogs have proven time and time again that they can get by just fine without them.
Do frogs have teeth?
Only one species of frog known to science has true teeth on both the upper and lower jaws. It’s a large marsupial frog, Gastrotheca guentheri, and it was first described back in 1882.
To earn the title of true teeth, mouth bones must have dentin and enamel, but spotting those constituent parts in a tooth the size of a grain of sand is easier said than done. Working out whether G. guentheri’s teeth were the genuine article was made even more complex by fears they may have gone extinct, after not being seen in their native habitat in the cloud forests of Colombia and Ecuador for quite some time.
Fortunately, these peculiar frogs – that carry their eggs in a back pouch and hatch as froglets, not tadpoles – were not extinct, and CT scans of their teeth revealed that both the upper and lower sets were packing dentin and enamel. The finding was surprising, as amphibians hadn’t had true teeth in their lower jaws for millions of years by the time this species evolved. It defies an idea known as Dollo’s Law, which states that once a complex trait has been lost in evolution, it doesn’t come back again.
The maxillary teeth of Ceratophrys cranwelli, seen at the top of the article.
What kind of teeth do frogs have?
G. guentheri might be the only frog with a mouthful of true teeth, but there are lots of species that have teeth on their upper jaw, known as maxillary teeth. Some frogs also have small teeth on the roof of their mouths, known as vomerine teeth.
Saber-toothed frogs have maxillary teeth and strange fang-like protrusions sticking up on their lower jaws. These fangs aren’t quite the same, however, as they lack the dentin-enamel makeup of true teeth, and they only grow once, whereas frog teeth are constantly lost and replaced.
Why do frogs need teeth?
Frog teeth have little to do with defense. They are sometimes used in “traumatic mating,” but a study into the evolutionary loss and gain of teeth among frogs found that diet appears to be the biggest factor, especially among animals eating tiny things like ants and other small insects.
Maxillary teeth come in handy when you’re munching on giant worms.
Image credit: Zaruba Ondrej/Shutterstock.com
“Having those teeth on the jaw to capture and hold on to prey becomes less important because they’re eating really small invertebrates that they can just bring into their mouth with their highly modified tongue,” said Daniel Paluh, a PhD candidate at the University of Florida’s department of biology, to Florida Museum. “That seems to relax the selective pressures that are maintaining teeth.”
As for your chances of ever seeing any frog teeth?
“If you open a frog’s mouth, chances are you will not see teeth even if they have them, because they’re usually less than a millimeter long,” Paluh added.
Put the frog down, people.
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