The Physiology of the Beaver


It’s rare that anyone gets to see a beaver up close in the wild. Of course, we all have an idea in our heads of what beavers look like: after all, they have been a Canadian national symbol for years.

However, beyond the big buck teeth and flat, floppy tail, the physiology of a beaver is actually very unique and geared towards their habitats. Their bodies are so fascinating that we’re going to break down some unique physical traits of the beaver point by point and explore what makes this rodent such a habitat engineering powerhouse. 

 

Head

 

  • The beaver has a large, broad head with extremely powerful jaws.


  • The beaver’s three main senses are hearing, smelling, and touch.


  • The beaver’s ears, nose, and eyes are located on the upper third of its head.


  • Beavers' rounded ears and small nostrils close tightly to keep water out, and their ears and noses also have vales that close automatically when they submerge.


  • A beaver actually has three eyelids on each eye, for a total of six eyelids per beaver. Beavers have two outer eyelids, one upper and lower, that fit around the eye, the same as a human. However, they have a transparent inner eyelid that slides over the eyeball like goggles, allowing them to see underwater.


  • On land, this inner eyelid also serves as protection from sharp twigs when the beaver is feeding or cutting down trees.


  • However, beavers can’t see that well and depend on their hearing and small to detect predators.

 

Teeth



 

  • Beavers, like the majority of rodents, have incisor teeth that grow their entire lives. They have a hard exterior enamel and soft inner dentine. That outer enamel is bright orange due to a high concentration of iron.

 

  • When a beaver gnaws on wood, the back part of its incisors wears down more quickly than the front covering. Due to this, their incisors have a sharp edge.

 

  • There are large gaps between the beaver’s incisors and their back teeth. Flaps of skin, one on each side of the mouth, fold inward and meet behind the incisors. These flaps seal off the back of the mouth, allowing the animal to gnaw wood on land or in water without getting splinters. These flaps open when the beaver wants to eat or drink.

 

Fur

 

  • Beaver fur is usually a shiny, dark brown that looks darker when wet.

 

  • Beaver fur is composed of two kinds. A short, soft underfur that helps insulate the beaver in cold water. Then the long, heavy guard hairs cover the underfur to protect it to keep it dry.

 

 

Tail


  • The tail of the beaver is one of the most interesting features. It’s stiff, flat, and appears like a paddle. It’s approximately 20 to 30.5 cm in length.

 

  • A small section of the tail nearest the beaver’s body has the same fur as the body. The rest is covered in black, scaly skin.

 

  • The tail is used as a prop for balance when the beaver stands on its hind legs to eat or cut down trees.

 

  • The tail is also used as a propeller through the water.

 

 

Feet



  • The front feet can be used to hold onto items while the back feet are used as flippers.


  • The front paws have five toes with long, thick claws. These claws can be used to dig up roots for food. The front paws are also used when constructing dams and lodges.


  • While swimming, beavers make a tight fist with their front paws and hold them against their chest to improve their swimming. They also use them to push underwater vegetation out of the way when swimming.


While beavers may appear a bit awkward on land, their bodies are perfectly engineered to fly elegantly through water and survive long, hard Canadian winters. These habitat engineers are quite incredible in their physiology, and now you know a little more about what makes these aquatic critters tick. 

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