Beaver Teeth: Everything You Need To Know

Written by Hannah Ward
Updated: December 26, 2021
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Beavers are large aquatic rodents that are best known for their distinctive paddle shaped tail and ability to construct dams.  There are two species of beaver alive today – North American and Eurasian beavers.  Both have large front teeth and are renowned for their ability to chew entire trees down.  But just what is so special about their teeth?  Join us as we discover everything you need to know about beaver teeth.

What are Beaver Teeth made from?

Beaver Teeth - Close up of Beaver Teeth

Beaver teeth are strong enough to chew through entire trees!

©Martin Janca/Shutterstock.com

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Beaver teeth are incredibly strong because they contain iron, which also gives their teeth their orange color!

The teeth of a beaver need to have incredible strength and toughness to chew through entire trees. But why are they so strong?  Well, it comes down to what they’re made from, and the clue to that is in their color.  If you’ve ever been close enough to a beaver to see it’s front teeth then it’s easy to notice that they are a striking orange color. As we just noted, that color comes from the fact beaver teeth contain iron!

Beavers have twenty teeth in total, including four incisors at the front – two upper and two lower. The roots of the lower incisors are extended into the jaw.  The rear of these incisors are made from dentin which, although tough, isn’t as tough as the front of their teeth.  This is because the front of their incisors is made from really tough enamel which contains iron compounds. This is the reason that they are rust colored orange.  These iron compounds make their teeth super strong durable and less likely to suffer any cracks or chips.  So, the iron in their teeth means that beavers are capable of gnawing through tough wood really fast without any tooth problems.  In fact, they’re so strong that a beaver can fell an eight foot tree in only five minutes!

Incredibly, these same iron compounds also make beavers teeth resistant against tooth decay.  The iron in their teeth makes them both stronger and resistant to harmful acids that can cause tooth decay.  Resistance to tooth decay is definitely a plus for beavers considering how much they use their teeth.  So, although rust-colored teeth are pretty unusual, beavers certainly get plenty of benefits from them.

Beavers incisors contain iron compounds which make them extremely strong

©Chuck Szmurlo / Creative Commons

Beavers Have Self Sharpening Teeth

Beavers eat a range of plants, twigs, and bark. This means their teeth must grow continuously so that they don’t get worn down by chewing on wood all day.  However, on the flip side they also have to keep gnawing on wood so that their teeth don’t get too long for their mouths!  As they’re chewing away on wood all the time it would be pretty easy for beavers teeth to become blunt and ineffective.  Therefore, they actually have a handy little trick that prevents this from happening – self sharpening teeth.

As we’ve already mentioned, beavers have four long incisor teeth at the front of their mouth which are made from dentin on the back and contain iron compounds on the front.  The softer dentin wears down quicker on the back of their teeth than the front of their teeth. This is because the front is much tougher due to the iron that they contain.  As the back wears down quicker than the front it creates a chisel-like shape. This is really effective for chewing through wood with.  The fact that they never stop growing, combined with the pattern of wear, means that beavers front teeth are self-sharpening.

Beavers molars also work much the same way that their incisors do.  Once their incisors have gnawed away at the wood, chunks are sent back for the molars to grind down.  Their molars are made of dentin and enamel just like their incisors (although minus the iron).  Therefore, just like on their front teeth, the dentin wears down quicker than the enamel does. This creates sharp ridges on their molars and these ridges then make it easier to grind down their food.  However, the ridges on the molars often wear away unevenly over time.

Two Beaver cubs playing

Beavers teeth never stop growing and are self-sharpening

©Donny Agung Prasetyo/Shutterstock.com

Ancient Beavers Had Even Bigger Giant Beaver Teeth!

Another interesting question that often comes up when we’re talking about beaver teeth is whether ancient beavers had teeth that worked the same way.  One of the first things to mention is that some ancient beavers were much, much bigger than modern beavers.  In fact, they were actually bear sized.  They also lacked the traditional paddle-shaped tail, having a skinnier one more like that of a muskrat.

Giant beavers – known by the genus Castoroides – had incisor teeth that were around 6 inches long.  Unlike the beavers that we see today have teeth that are coated with smooth enamel, giant beavers had teeth with tough enamel ridges on them.  They also lacked the chisel-like cutting edge that modern beaver teeth have.  Research suggests that giant beavers ate a diet of predominantly aquatic plants, rather than the woody diet that today’s beavers enjoy.  Along with the lack of a cutting edge to their teeth, this suggests that giant beavers weren’t the tree-chopping dam-builders that they are today.  This also means that they were reliant on existing wetland habitats for their survival as they didn’t have the ability to alter water courses for their own benefit. It’s believed that this ultimately led to their eventual extinction around 12,000 years ago.

However, if we go even further back to an ancestor of the giant beaver, we find Dipoides – a not so giant beaver which is believed to be a common ancestor to today’s beavers.  Studies have suggested that Dipoides did have a taste for wood and cut down trees with rounded teeth for food and possibly dam building.  However, they gnawed with just one tooth at a time which took much longer than it takes modern beavers with their highly adapted teeth.

The photo featured at the top of this post is © U. Eisenlohr/Shutterstock.com


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About the Author

Hannah is a writer at A-Z animals where her primary focus is on reptiles, marine life, mammals, and geography. Hannah has been writing and researching animals for four years alongside running her family farm. A resident of the UK, Hannah loves riding horses and creating short stories.

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