#SciFri: Do frogs have teeth?
Recently I’ve had a number of conversations with people regarding amphibians (partly whilst recording various podcasts) and one question has been repeatedly asked about frogs. Do they have teeth? Let’s take a quick step back here, we know amphibians evolved from fish and fish have teeth. We also know that reptiles evolved from amphibians and they have teeth, just think of a crocodile or a snake. In both of these groups however there are examples of animals that have lost the ability to grow teeth such as sea horses and sea turtles. So what about frogs?
The simple answer is yes, frogs do have teeth. However they are only found in the top jaw due to the way their tongue hinges from the front of their mouth. The last thing they’d want to do is bite down on prey and then accidentally bite their tongue off. The teeth of frogs are unlike our own in that they grow in both the maxilla and the vomer. On top of this, they don’t have roots or any of the shiny gubbins we do, they grow directly out of the bone. This may sound weird but the teeth in frogs (and other amphibians) are only there to secure prey whilst it is being swallowed. As mentioned already, a frog’s tongue is attached to the front of it’s mouth. This means it isn’t much use in helping to swallow. Instead a frog uses it’s eyes to help push food down it’s throat.
The only group of amphibians that have teeth resembling something like our own are caecilians. This is likely due to the fact that like snakes, they are legless and so without limbs it is a lot harder to hold onto prey. Most amphibians don’t tear prey up but instead swallow it whole. Caecilians however do break their food up, which is another reason why they have teeth in their lower jaw to help assist with this. If you’ve ever seen a CT scan of a caecilian skull, you’ll know what I mean.
This then usually leads into the next question of can frogs bite? Well any animal with a mouth can bite, whether it will is a whole matter entirely. In most cases, frogs rarely bite and even if they did the worst you’re going to experience is a small pinch (maybe a cut, depending on the species). I’ve had newts try to bite me in the past when they’ve been unhappy and trapped in a bottle trap. I’m still waiting for my superpowers although I’m not sure if my scowl of disbelief has made them null and void. Whilst swabbing midwife toads for our ongoing project, I’ve also snagged the swab on the teeth in their maxilla/vomer so they are definitely there.
With all of this in mind hopefully things are a lot clearer. Yes frogs have teeth as trying to gum a slippery yet tasty worm is a near impossible feat. If a frog smiled, you wouldn’t see any teeth in the lower jaw but you may in the upper. Next time you’ve got a frog in the hand, why not ask them more about their pearly whites?
Edit: The great Darren Naish (@TetZoo) has rightly pointed out that one group of frogs (the marsupial treefrogs in the genus Gastrotheca) includes species with teeth located in the lower jaw. Many species of frogs have also evolved tooth-mimicking structures called odontoids in the lower jaw. So next time I won’t be so generalist as there is always someone that breaks the rules!
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