The "tail" is only possessed by the male and is an extension of the cloaca and used to inseminate the female.
ðə "tˈeɪl" ɪz ˈoʊnli pəzˈɛst baɪ ðə mˈeɪl ænd ɪz ɐn ɛkstˈɛnʃən ʌvðə klˈoʊkə ænd jˈuːzd tʊ ɪnsˈɛmɪnˌeɪt ðə fˈiːmeɪl.