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Bears belong to the family Ursidae, with eight species living worldwide and three species living in North America. I saw a comment on a recent video that asked if bears were mammals and realized that not everyone knows which animal family they belong to. 

All bears are mammals and have six of the seven mammalian traits. Bears are vertebrates, have mammary glands which they use to feed their live young, have a four-chambered heart, have hair, possess a large neocortex, and have three inner ear bones. However, bears do not have sweat glands.

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

Bear cub

Is A Bear A Vertebrate?

The first characteristic that all mammals share is that they have a backbone inside their body. However, it is not just mammals that have a backbone. Other animals, including amphibians, reptiles, fish, 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. Some examples include earthworms, starfish, single-celled organisms, octopuses, clams, insects, snails, and spiders.

Bears are classed as vertebrates as they have a backbone inside their bodies. The spinal cord of the bear is surrounded by cartilage or bone. All mammals are vertebrates and have a backbone.

If you want to know about how bears evolved, then I have written an article you can find here.

Do Bears Have Mammary Glands?

Another characteristic that mammals share is that they have mammary glands. Bears do have mammary glands.

Mammary glands are used to produce milk, which is fed to the young after birth. Mammals give birth to live young, although the duck-billed platypus and the echidna give birth to eggs. Milk is produced in the mammary glands after birth and is called lactation. Bears have milk within their mammary glands to feed their cubs.

Different species of bears have other numbers of mammary glands. Polar bears have four mammary glands, whereas the brown bear and the American black bear have six nipples.

Polar bear cubs can feed on their mother’s milk for up to 30 months, although this can also be as short as 18 months before they are fully weaned off. Brown bears nurse until they are five months old, while black bears are usually weaned off milk between six and eight months. The milk contains essential nutrients for bears in the early stages to grow healthy.  

The name mammal is taken from the Latin word mamma, which means breast, and was popularised by Carl Linnaeus, a Swedish botanist and zoologist.

Does A Bear Have A Four-Chambered Heart?

Bears have a four-chambered heart, along with all other mammals. The four-chambered nature is essential for the respiratory system of mammals and for them to survive. Oxygen is needed to survive, and carbon dioxide, a waste product, is expelled back into the air when mammals breathe out.

The respiratory system allows mammals to breathe in oxygen and expel carbon dioxide. 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 the arteries to the rest of the 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 for their survival. Four-chambered seats are necessary for warm-blooded animals as they use a lot of energy to keep warm. To do this, they require a lot of oxygen. The four-chambered heart is an efficient way of getting large amounts of oxygen into the body.

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

Want to find out if bears can climb trees? Find out here.

Brown bear

Do Bears Have Hair?

Another characteristic of a mammal is that they have fur or hair. Skin is generally used when a mammal has very thick body hair. Humans have hair, whereas other mammals, such as bears, would be said to have fur. The fur consists of two layers. These consist of a layer of oily guard hairs on top and a thicker underfur.  

The guard hairs are more extended and coarser than the underfur. Guard hairs are used to repel water from the skin and block ultraviolet rays from the sun. Animals with markings, such as jaguars, have these markings on the guard hair layer. The thick underfur is also called down fur. The down fur is used to keep the animal warm and is made up of curly, wavy hairs.

Bears have a thick coat of fur, which comes in many different colors. Brown bears have brown hair and black, cinnamon, reddish-brown or yellowish-brown.  

Polar bears appear white, which allows them to blend into their icy environment, but their fur contains no white pigment. The coat of a polar bear is transparent and hollow. Polar bears have black skin, which allows them to keep warm from the sun.

Do Bears Have Sweat Glands?

Bears do not have sweat glands and use other ways of cooling down. Bears have a thick coat of fur, which gets very hot in warm weather. They use methods such as resting in the shade, panting, which they share with dogs, entering into the water and lying down with their stomachs touching the ground. Although bears do not have sweat glands, they are still mammals.

Mammals are endothermic and need to regulate their temperatures; most do this by sweating.

Sweating is a way of regulating body temperature and not overheating, although not all mammals do this. Sweat glands produce sweat, releasing heat from the body by evaporation, making us feel calmer.

Many people think that black bears only eat meat.  However, their diet consists of many types of food.  Please find out more in this article I wrote.

Do Bears Have A Neocortex?

The brain is one of the most complex organs in a mammal’s body. The cerebral cortex is the brain’s outer layer and is used for functions such as movement, decision-making, processing information, and speech. 

study by Suzanna Herculano-Houzel, a psychology professor at Vanderbilt University, found that brown bears have a cortex that weighs 222 grams.

It was found that brown bears had 251 million neurons in their brains. Brown bears were the giant brains in the study, but although they had big brains, the number of neurons (nerve cells) was the same as a domestic cat. The domestic cat has a brain one-tenth the size of a brown bear. Non-neuronal cells were found to be ten times the amount of the cat.

The neocortex is a set of layers of the cerebral cortex, and it is the neocortex that controls motor commands, spatial reasoning, sensory perception, and conscious thought. The larger the neocortex, the larger the capacity for the mammal to handle these. The neocortex also allows mammals to store memories, including past experiences and events.  

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

The neocortex looks different in different animals. Primates, humans, and larger animals have grooves (sulci) and ridges (gyri). The tracks, bumps, and folds allow a large neocortex to fit inside a smaller braincase. Smaller mammals like rodents do not have deep grooves and ridges. The neocortex in these animals is also much smoother.

Black bears aren’t just black; polar bears don’t have white fur.  Please find out more in this article I wrote.

Do Bears Have Three Middle Ear Bones?

Another characteristic that bears possess is three bones in the middle ear. The three small bones, called ossicles, conduct vibrations (sound) to the eardrum’s inner ear. The three bones are called the hammer, the anvil, and the stirrup.

Once the vibrations are in the inner ear, the vibrations are converted into nerve impulses sent to the brain. These three bones play a vital role in a mammal’s hearing ability. With many animals relying on their sense of hearing to hear both predators and prey, excellent hearing is essential for mammals to survive.

Bears have three small inner ear bones that help them to hear. Bears have excellent hearing, and it has been observed that they can listen over greater distances than they can see.  A bear’s hearing has a more excellent frequency range than humans’ and is also over twice the sensitivity.

If you want to learn about bear hibernation, I have written this article

References and Sources

American Society of Mammalogists – Mammalian Species, Issue 145, 8 May 1981, Pages 1–7

American Society of Mammalogists – Mammalian Species, Issue 439, 23 April 1993, Pages 1–10

American Society of Mammalogists – Mammalian Species, Issue 647, 23 January 2001, Pages 1–11

Study – Dogs Have the Most Neurons, Though Not the Largest Brain: Trade-Off between Body Mass and Number of Neurons in the Cerebral Cortex of Large Carnivoran Species

Brown, Gary. The Bear Almanac : A Comprehensive Guide to the Bears of the World. Guilford, Conn., Lyons Press, 2013.‌