The tail's 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's 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… (More on Tail)