An animal’s tail can serve the animal in many different ways. When this question is asked, you principally see explanations of the tail as a counterbalance measure for the animal. Certainly, counterbalance explains the function of the tail on some animals. Arboreal species may require very specific balance when walking on thin tree-limbs. Even in a cat, where the tail is not at all times useful, the mechanism of the tail allows it to “land on its feet” if the cat falls.

Other arboreal species like the possum have tails that can actually help them hang onto trees and catch branches as needed. Many primates, like lemurs, also use their tail to enhance tree-climbing ability and to provide balance. Yet balance is not the only explanation.

In many new world monkeys, tails are prehensile. The prehensile tail allows the animal to snatch or grab with the tail. It can grab onto tree limbs, or even pull food off bushes. It really serves as an extra hand. Some animals have what is called a partially prehensile tail. It can’t be used for food gathering, but can be used for holding on to trees. Animals with partially prehensile tails include rats, tree porcupines, and anteaters. Reptiles like snakes and many species of lizards and newts have partially prehensile tails.

A tail can serve completely different functions for an animal. Obviously a horse doesn’t need to snatch or grab at trees. Horses, and other farm animals like cows, use tails primarily to aid in their comfort. Swishing tail action can help keep annoying flies from biting the animal. Many others animals have this fly swatter action, like the giraffe, zebra and elephant.

The tail and tail feathers in birds can serve in many ways. First, in birds that fly, the tail may be used for direction and better aerodynamics when flying. Flightless birds, like penguins, use their tails when swimming to change directions. Tails in male birds often help to attract mates. Nowhere is this more evident than in the tail of the peacock, which has elaborate tail feathers meant to stir the interest of peahens.

In marine animals, tails are extremely important. Powerful thrusts of the dolphin's tail push it forward more quickly. The tail in many fish species also promotes better and faster swimming and directional capabilities.

The tail in the lizard may be partially prehensile, but is also used as a defense mechanism. When lizards attempt to escape predators, many of them have tails that can safely detach. This allows the lizard to escape a predator that grabs it by the tail. Further, the lizard can grow a new tail after detaching one, so it can live to defend itself another day.

There are some very specialized tails in the animal kingdom. The rattle at the end of the rattlesnake’s tail is a warning to predators to stay away. Deer use their tails to communicate potential danger. The powerful sting on the end of the scorpion’s tail makes for an excellent weapon, as does the long strong tail of the crocodile. Badgers have flat tails useful for swimming and conferring warnings, and dogs use their tails to communicate emotions. Specific benefits of the tail in each animal are often beautifully adapted to the animal’s needs.