Why Do Mammals Have Tails?

Many mammals have tails, and I wanted to find out what the reasons for this were? I know that dogs use their tails to convey emotion and that some monkeys use their tails to swing from branch to branch. I also wanted to find out what mammals do not have tails and why we do not have one.

Mammals use their tails in various ways. They use them to show emotion, such as a dog wagging their tail. They can use them to protect them from wintery conditions, such as an arctic fox, and they can also use them to aid in balance, navigation, and even to keep flies away from their bodies.

The tail is essential to a lot of mammals, and I wanted to discuss here some of the many ways different mammals use tails to their advantage.

What is a Tail?

The tail is a section at the rear end of certain kinds of animal’s bodies. A tail is a flexible appendage to the torso. The tail is also regarded as the hindmost part of an animal especially if the tail points out from the rest of the body.

Almost all mammals have a tail. The tail can be short, curled or long. Tails have evolved for specific purposes depending on the animal. 

Ever wondered what the different orders of mammals are? You can find out in this article I have written.

Why Do Mammals Have Tails?


Tails assist animals in maintaining balance. The tail is used as an aid to help animals keep upright and balanced. The tail helps many mammals navigate through tight spaces and small gaps, acting as a rudder to direct the animals through thick undergrowth.  

Bats have tails, despite their small body size. They use the tail to steer when flying and also to help maintain balance when sitting. For species of bats without a tail, they find it more difficult to maneuver in the air than bats with tails. For bats with tails, this appendage helps them when flying. When bats use the tail together with the wings, they can navigate easier and turn faster. 

Another example of a tail aiding balance is when a dog is running at high speed. When the dog tries to take a tight turn, they use their tail for stability. The tails serve the purpose of aiding the dog in keeping their balance.  


The tail is used by animals to communicate. Most mammals have tails, and they use them to communicate with others. For instance, a dog wagging their tail serves a lot of functions. They may be communicating that they are happy, but this is not always the case.

White-tailed Deer

The different tail positions also communicate a lot of meaning from what the dog is thinking. When the tail is high, this it is an indication that the dog is alert. It can also be held high to portray dominance. If the dog tail is held high but also wagging, then this indicates happiness. This can also be shown as a sign of alertness.

According to recent research, the direction of a dogs wagging tails means different emotions. A tail wagging to the right means that the dog is feeling good.

Their tail often wags to the right when they are with someone they know, or when seeing some he or she knows approaching. When the dog wags their tail to the left, it means the dog is with someone who they do not recognize and is a sign to show dominance. 

Tails are used by mammals to express emotions. Dogs use their tails to express affection and hold them straight out when angry. They will wail their tails when happy from one side to another. 

Cats hold up their tails for affection and wag their tails mostly when they are displeased or upset. 

Horses also use the tail to express emotions by swishing its tail when in pain or stressed. They raise their tails when excited and alert to dangers. A tail pointed straight down to the ground can show nervousness.


Mammals use their tails for self-defense and survival. Animals use their tail to protect themselves from predators. Rats are known to shed off part of their tail when attacked by the tail, allowing them to escape.

Humpback Whale (Megaptera novaeangliae) tale-Cape Cod, Massachusetts

Fly Swatter

Animals use the tail to keep flies away. Flies disturb animals so much, and the tail helps them keep them away. A good example is a cow, especially on a warm sunny day where many flies buzz around their head and body. It can be a very disturbing and irritating situation, and a cow uses its tail to brush away the flies.


Animals use their tails to protect them from cold. Animals which live in colder regions curl up and use their furry tails to cover up their nose from the cold. Arctic foxes use this mechanism, especially at night when it is even colder.


Sea mammals use their tails to navigate through water. Whales have a tail fin which they use to propel themselves through the water. They also use the tail to slap on the surface of the water as a way of communicating.

The tails of some whales like humpbacks have distinctive markings that enable researchers and scientists to identify each whale personally.

Ever wondered why mammals have hair? You can find out in an article I have written here.

Why do Some Mammals Have Tails When Humans Don’t?

It is believed that a million years ago humans had tails, and that we used them much for the same reasons as stated above. But today humans, unlike other mammals, do not need tails for these reasons. 

Human embryos do have an appendage that looks like a tail. This starts at about four weeks of age, but white blood cells dissolve the tail between the ages of six and twelve weeks.

To be able to understand the reasons why we do not have a tail anymore, we need to look at these reasons. Humans walk completely upright, whereas monkeys walk with their chests diagonally to the floor when on two feet.

Photo of cougar

When walking upright, we do not need a tail to balance, unlike the four-legged mammals. Humans ability to walk upright on two legs prevents the head from overbalancing us, as it would in four-legged mammals.  

Despite the tail disappearing through evolution in humans, we do still have a tailbone. The tailbone, also known as the coccyx is a triangular bone resembling a shortened tail located at the bottom of the spine. 

The tailbone serves as an attachment site for tendons, ligaments, and muscles. It also serves as an insertion point for some of the muscles in the pelvic floor. Another important function is that the tailbone supports and stabilizes a person while he or she is in the sitting position.

Do all Mammals Have Tails?

There is a range of more than 4000 species of mammals all over the world, and most have mammals have tails except humans and some species of bat. Both had tails at one time but evolved over time, disappearing and becoming almost invisible.

Unlike hair, being warm-blooded, being fed milk, and being born alive, tails are not a classification factor to determine if an animal is a mammal.

Mammals that do not have tails are the hog-nosed bat and humans. Despite not showing visible tails, they both have a tailbone (coccyx). The tailbone does not protrude externally. 


Tails in animals are used in a variety of ways and are essential to four-legged mammals. The tail serves to:

  • Helps in locomotion for marine mammals
  • Helps animals brush away the flies
  • Helps to keep balance
  • Allow some animals to grasp tree branches
  • For social signaling and to help escape from predators
  • Help bats steer and maneuver in flight. 

Ever wondered if all mammals are warm-blooded. Find out in this article I have written.

Bryan Harding

Bryan has spent his whole life around animals. While loving all animals, Bryan is especially fond of mammals and has studied and worked with them around the world. Not only does Bryan share his knowledge and experience with our readers, but he also serves as owner, editor, and publisher of North American Mammals.

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