Tail

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For other uses, see Tail (disambiguation).

A scorpion tail

A tail is the section at the rear end of an animal's body, the term particularly referring to such a section which forms a distinct, flexible appendage to the torso. It is the part of the body that roughly corresponds to the sacrum and coccyx in mammals and birds. Tails are mostly a feature of vertebrates, however some invertebrates have tail-like appendages, such as the tail of the scorpion, or the furcula of the springtail.

[edit] Function

Tails perform various different functions in animals. They are used by fish and other marine life for locomotion, while some land animals use them for balance (e.g. cats) or even for grasping (e.g. monkeys).

Tails can also be useful as for social signals, as used by deer to warn of possible danger, or by domestic dogs to indicate emotions. Different evolutionary pressures have led to armored tails, some containing venom, as in the case of scorpions.

In some species of lizard, the tail is able to be permanently detached ("cast") from the body if necessary, with the intent of escaping a grip or distracting a predator long enough to allow the lizard to escape. Usually their tails will grow back over time, though generally darker in color than the original.

In most birds, tails consist of feathers of extended length, the function of which is to act as a rudder to balance and steer the bird in flight, also to provide balance when perched.

[edit] Human tails

Human embryos have a tail that measures about one-sixth of the size of the embryo itself. As the embryo develops into a fetus, the tail is absorbed by the growing body. The developmental tail is thus a human vestigial structure (an atavism). Infrequently, a child is born with a "soft tail", which contains no vertebrae, but only blood vessels, muscles, and nerves; although there have been a very few documented cases of tails containing cartilage or up to five vertebrae. Modern procedures allow doctors to eliminate the tail at delivery. The longest human tail on record belonged to a twelve-year-old boy living in what was then French Indochina, which measured nine inches (229 mm).^[1] A sound case is that of a man named Chandre Oram who was born in India and has been famous because of his 13-inch tail. Nonetheless, it is believed it is not a true tail but a case of spina bifida.

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.