Telson
The telson is the final division of the body of a crustacean. It is not considered to be a true body segment because it does not form in the embryo in the same way as do real segments. The telson also does not have any appendages, although it may be split or forked to give that illusion at times. When this take place, it is called a caudal furca. The telson and the uropods collectively form the familiar fanned tail of crayfish, lobstes, shrimp and other decapods