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There are two species of beaver in North America; the North American and the mountain. Somebody asked me if they were both species of mammals.

Beavers are mammals and have several mammalian traits. Beavers are vertebrates; they use mammary glands to feed their live young, have a four-chambered heart, have fun, and have sweat glands to cool down.

Please read on if you want to learn more about the characteristics that beavers share with other mammals.

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Is A Beaver A Vertebrate?

One of the characteristics that all mammals have is that they have a backbone inside their body. However, it is not just mammals that have a backbone.

Other animals, such as fish, amphibians, reptiles, and birds, have a backbone. Animals with a backbone are called vertebrates.

There is another group of animals called invertebrates. These are animals that don’t have a backbone inside their body. Examples include single-celled organisms, earthworms, starfish, octopuses, snails, clams, insects, and spiders.

Beavers are classed as vertebrates with a backbone inside their bodies. The spinal cord is surrounded by cartilage or bone.

Do you know if beavers can see in the dark?  Find out the answer here

Does A Beaver Have Mammary Glands?

Another characteristic that mammals have is mammary glands. The name mammal is taken from the Latin word mamma, which means breast, and was popularised by Carl Linnaeus, a Swedish botanist and zoologist.

Mammary glands are used to produce milk to feed the young after birth. Milk is made in the mammary gland after childbirth and is called lactation.  

Beavers produce milk within their mammary glands. Beavers have four nipples, only visible when the female is lactating. This is one of the only ways to tell the difference between male and female beavers.

Beavers usually give birth to between one and six kits. Beavers are fully weaned off milk from their mother at about six weeks. The milk contains essential nutrients for beavers in the early stages of growing healthy.  

Did you know that beavers are good for the environment? Find out more here.

Beaver couple

Does A Beaver Have A Four-Chambered Heart?

Mammals all share another characteristic, one which is also shared with birds. Both birds and mammals have a heart that contains four chambers. Surprisingly, crocodiles, a reptile, also have four-chambered seats.

The four-chambered heart is essential for the respiratory system of mammals. When mammals breathe in air, they take in oxygen. Oxygen is needed to survive, but the waste product is carbon dioxide once the oxygen has performed its function. Carbon dioxide is expelled back into the air when we breathe out.

The respiratory system allows us to breathe in oxygen and carbon dioxide out. Oxygen enters the lungs, where the body’s cells transport it through the blood to the heart’s left ventricle. The left ventricle pumps oxygen-rich blood to the left atrium. It is then pumped through your arteries to the rest of your body. 

The other two heart chambers are the right atria and the right ventricle. Oxygen-poor blood is received from the veins and is pumped to the lungs, where the carbon dioxide is expelled.

The four-chambered heart that mammals possess is essential. A four-chambered heart is necessary for warm-blooded animals as they expend energy and oxygen. The four-chambered heart is an efficient way of getting lots of oxygen into the body.

Beavers do have a four-chambered heart. Beavers need plenty of oxygen as it is required to burn sugars and fatty acids in their cells to produce energy. The energy is needed for everything they do, including keeping themselves at a steady temperature.

American Beaver: Master Builders of the Waterways – Explore the fascinating life of the American beaver, an expert engineer shaping North American waterways. Learn about its dam-building skills and ecological impact.

Do Beavers Have Hair?

Another characteristic of a mammal is that they have hair or fur. The fur is generally used when a mammal has very thick body hair. Humans have hair, but we wouldn’t call it fur, whereas other mammals covered, such as bears or raccoons, would have fur.

Hair or fur consists of two layers. These consist of a thicker underfur covered with oily guard hairs on top.  

The guard hairs are longer and coarser. They repel water from the skin and block the sun’s ultraviolet rays. In animals with markings, such as a jaguar, these markings are on the guard hair layer.

The thick underfur, or down fur, is used to keep the animal warm and is made up of curly or wavy hairs.

Even whales and dolphins have hair, although some species only have hair follicles. Species such as the humpback whale have hair their entire life, with a single hair coming out of each hair follicle.  Toothed whales usually lose their hair shortly after birth.

As anyone who has seen a beaver knows, they have a coat of fur. The hair on a beaver is also known as fur, and beavers have been hunted for their skin.

North American beavers have thick, waterproof fur, which keeps them dry and warm.

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Do Beavers Have Sweat Glands?

Mammals need to regulate their temperatures, and although all mammals sweat, not all cool down the same way.

For us, sweating is a way of regulating our body temperature so we don’t overheat. The sweat glands produce sweat, which evaporation carries away from the body. This carries out the heat and makes us feel cooler.  

Humans aren’t the only mammals that sweat through their skin. Primates and horses also sweat through sweat glands.

Some other animals use different ways to expel heat from their bodies. These can include panting, which you see in dogs when they have been out playing. This allows them to get rid of heat through their mouth.

Most mammals do not have sweat glands like we do and need to use these other ways to cool down.

Beavers are one of the strangest mammals regarding sweating as they do sweat, but not in the way we do. Beavers have sweat glands on their bodies, but as their fur covers most of them, they do not provide an excellent way to cool down. Beavers have sweat glands on their paws and sweat using these.

Do you know how big beavers grow? Do their teeth ever stop growing? Find out here

Do Beavers Have A Neocortex?

The brain is one of the most complex organs in a mammal’s body. There are many areas in the brain.  

The cerebral cortex is the brain’s outer layer and is used for functions such as movement, processing information from the five senses, decision-making, and in humans, speech. 

The neocortex is a set of layers of the cerebral cortex, and this part of the brain controls sensory perception, motor commands, spatial reasoning, and conscious thought.

The neocortex also allows mammals to store memories, including experiences and events.  

The larger the neocortex, the larger the capacity to control conscious thought, spatial reasoning, motor commands, and sensory perception.

The majority of brain cells are found in the neocortex and the cerebellum. The cerebellum is used for posture, coordination, and balance.

The neocortex looks different in different animals. Humans, primates, and other larger animals have grooves (sulci) and ridges (gyri), and the brain is similar to what you may have seen. The tracks, bumps, and folds allow a much larger neocortex to fit inside a smaller space.

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Small mammals like rodents do not have deep grooves and ridges, and the neocortex is much smoother. This shows that their brains are much smaller in comparison.

A 17kg beaver has a brain that weighs about 45g, and its intelligence is thought to be between rodents of its size and squirrels.

Beavers have a neocortex, but there are fewer folds and a smaller neocortex relative to their brain size.  However, the brain size is no different from that of a non-aquatic mammal.

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Do Beavers Have Three Middle Ear Bones?

Another trait that mammals possess is three bones in the middle ear. These three small bones are called ossicles and conduct vibrations (sound) to the eardrum’s inner ear.

The three bones are called the malleus (hammer), the incus (anvil), and the stapes (stirrup).

Once the vibrations are in the inner ear, the vibrations are converted into nerve impulses. These three bones play a vital role in a mammal’s hearing ability.

With many animals relying on their sense of hearing for prey and predators, this evolutionary trait is essential for mammals to survive.

Beavers have three small inner ear bones, which help them hear. Beavers have had these three earbones for millions of years as fossils from the Pleistocene beavers also had these bones.

Beavers have a good sense of hearing, which we know as they react to tail slaps from other beavers. Females slapping their tails makes beavers move to deeper water, for example.

However, I have not found proof of how good a beaver’s hearing is.

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If you or someone you know loves beavers, look at my favorite beaver gifts on Amazon.