I suppose all of you know about beavers. They are one of the large aquatic rodents in this world. They are very famous for their ability to build dams and for their paddle-shaped distinctive tail. There are only two different species of beavers alive today called Eurasian beavers and North American beavers. Both of these species have large front teeth and are best known for their ability to chew down trees. Their teeth are very special and today I’m going to tell you some interesting facts about them!

            One interesting fact about beavers is their ability to stay underwater. The fur on their body is waterproof and very oily. And also their eyelids act like goggles and their webbed feet operate like swimming fans. With all these facts, they can stay more than fifteen minutes under the water.

Have you ever been close to a beaver to see its front teeth? If you are close enough, you can easily notice that those teeth are orange-colored. The teeth of beavers need to be incredibly strong and tough to chew large trees. Can you imagine why they are so strong? How do they become strong? Well, the clue for that is in their color. The amazing orange color comes to their teeth because they contain iron!

            Usually, beavers have twenty teeth. Four of them are located as incisors at the front, two lower and two uppers. The roots of those lower incisors are extended into their jaw. The rear areas of all the incisors are created from dentin. They are also tough but are not tough as the front area of their teeth. As mentioned before, the reason for this is the though enamel which the front of their incisors are made from. This is also the reason for the rusty orange color of their teeth.

Because of the iron compounds, their teeth become durable, super strong, and less likely to suffer from chips and cracks. So the iron compounds in their teeth help beavers to gnaw through tough woods without causing any tooth problems. A beaver can fall down an 8 feet tree within five minutes using its teeth. Just imagine the strength of their teeth!

            And also the same iron compounds help beaver teeth to resist tooth decay. Those compounds make teeth resistant to harmful acids which cause tooth decay. When considering how much beavers use their teeth, resistance they have against tooth decay is absolutely a plus. Even though orange-colored teeth are very unusual, beavers get lots of benefits from those teeth.

            When considering about beaver diet, they eat a wide variety of bark, plants, and twigs. To prevent them get worn down by chewing wood all day, their teeth must need to grow continuously. However, on the other side, beavers have to gnaw wood all day to prevent growing their teeth longer than their mouths! As they are chewing wood all the time, their teeth can easily become ineffective and blunt. Therefore, they have actually got a little trick to prevent this from happening. It is self-sharpening teeth.

These front teeth, called incisors actually never stop growing. Normally these incisors can grow up to 4 feet per year. It is the length of an adult beaver body without a tail! As I have already mentioned before, four incisors of beavers contain iron compounds on the front and dentine on the back. The softer dentine on the back of their incistors wears down more quickly than the iron compounds in the front. As the back wears down quicker, it causes to create a chisel-like shape in their teeth. It is actually effective for beavers to chew through the woods. When combining the pattern of wearing and the pattern of growing their teeth, we can identify that beavers’ front teeth are self-sharpening.

            Beaver molars also operate and work in the same way as their incisors do. Once the incisors gnaw the wood, their chunks are sent to the molars to grind. Those molars are also made from dentine and enamel just same as their incisors are made from.  Therefore, just like in their incisors, dentine on the molars wears down more quickly than the enamel. This causes them to create sharp ridges on molars and those ridges help them to easily grind down their diet.

            Now you may be wondering about what ancient beavers looked like! You may have the question of whether ancient beavers had teeth that worked in the same manner. Before answering that question, I would like to mention something. Actually, most of the ancient beavers were much bigger than the ones in the modern world. Most of them were actually bear-sized. And also they didn’t have the paddle-shaped tails that modern beavers have. Instead of that, they had skinner tails like that of muskrats.

Giant ancient beavers are known as genus Castoroides and they had incisors that were more than six inches in length. Even though modern beavers have teeth coated with smooth enamel, giant beavers teeth had tough enamel ridges. They also didn’t have chisel-like cutting edges that modern beavers have.

            According to researchers, giant beavers had a diet consisting of predominantly aquatic plants unlike the woody diet of modern beavers. As giant beavers didn’t have cutting edges on their teeth, it suggests that giant beavers weren’t some tree-chopping dam builders like modern beavers. This also means they had to rely on existing wetland habitats as they couldn’t alter water courses. When considering all these facts, it is believed that the extinction of the giant beavers happened around 12,000 years ago.

            But if we go further back, we find an ancestor of the giant beaver called Dipoides. They were not much bigger than giant beavers. As research studies suggest, Dipoides have tasted wood and cut down trees with rounded teeth they had. Sometimes it may be for food or possibly for dam building. However, unlike modern beavers, they didn’t have highly adapted teeth. So they gnawed with a single tooth at a time and it took much longer to fall down a tree.


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