Tail

For other uses, see Tail (disambiguation).

The tail is the section at the rear end of an animal\'s body; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammals and birds. While tails are primarily a feature of vertebrates, some invertebrates—including scorpions and springtails—have tail-like appendages.

Function

Animal tails are used in a variety of ways. They provide a source of locomotion for fish and some other forms of marine life. Many land animals use their tails to brush away flies and other biting insects. Some species, including cats and kangaroos, use their tails for balance, and some, such as New World monkeys and opossums, use their prehensile tails to grasp tree branches.

Peacock in full courtship display

Tails are also used for social signaling. Some deer species flash the white underside of their tails to warn other nearby deer of possible danger, and canids (including domestic dogs) indicate emotions through the positioning of their tails. Evolutionary pressures have led to the development of armored tails in some species, and some, such as the tails of scorpions contain venom.

Some species of lizard can detach ("cast") their tails from their bodies. This can help them to escape from predators, which are either distracted by the wriggling detached tail, or left with only the tail while the rest of the lizard flees. Tails cast in this manner generally grow back over time, though the replacement is typically darker in color than the original.

The tails of most birds end in long feathers called rectrices. These feathers are used as a rudder, helping the bird to steer and maneuver in flight; they also help the bird to balance while it is perched. In some species—such as birds of paradise, lyrebirds and peacocks—modified tail feathers play an important role in courtship displays. The extra-stiff tail feathers of other species, including woodpeckers and woodcreepers, allow them to brace themselves firmly against tree trunks.

Human tails

Human embryos have a tail that measures about one-sixth of the size of the embryo itself.Humans have a tail bone (the coccyx) attached to the pelvis, in the same place which other mammals have tails. The tail bone is formed of fused vertebrae, usually four, at the bottom of the vertebral column. It doesn\'t protrude externally, but retains an anatomical purpose: providing an attachment for muscles like the gluteus maximus.

References

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Tails

• (2001) in Chris Elphick, John B. Dunning, Jr. and David Sibley: The Sibley Guide to Bird Life & Behaviour. London: Christopher Helm. ISBN 0-7136-6250-6. 

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