Animal tails have many uses, both for keeping balance and for sending messages

The tail is the part extending from the end of the body in many animals, generally made up of vertebrae, muscles and skin, and it is one of the most varied parts of a vertebrate's body. Because different animals live in different environments, tails differ greatly in length, thickness and shape, and their uses are emphasized in different ways.

Keeping balance and helping with movement are the most common uses of a tail. When a cat walks along a wall top or a tree branch, it relies on its tail to adjust its center of gravity at any moment; when a monkey leaps through the forest, its tail helps steady its body, and the tails of some monkeys can even wrap around branches, like an extra hand. In the water, the tail becomes a tool for moving forward: fish swing their tail fins to produce thrust, and whales and crocodiles also rely on their tails to swim agilely in the water.

Tails can also take on the tasks of keeping warm and defending. When the weather is cold, foxes and squirrels often cover themselves with their fluffy tails, as if covered by a small quilt; reptiles such as geckos will actively shed their tails to survive when they encounter natural enemies, and after some time the tail can grow back; horses and cattle, meanwhile, swish their tails all day long to drive away mosquitoes and insects.

For many animals, the tail is also a signal for communication. When a dog is excited or happy it wags its tail, and when a cat holds its tail straight up it often means it is relaxed and friendly toward people; when a deer senses danger it raises its white tail high to remind its companions to dodge quickly, and beavers also slap the water with their tails to sound an alarm. Observing the posture of a tail can often reveal an animal's current mood and state.

Although humans do not have an exposed tail, the end of the spine still retains a vestigial tailbone, a trace left by evolution. The small tail may seem inconspicuous, but it is an important helper for animals adapting to their environment, and also a window through which we can understand animal behavior.