The end opposite from the oral or mouth end. In many athecate hydranths, the tentacles are to some extent separated into an oral whorl (the oral tentacles) near the mouth end and an aboral whorl (the aboral tentacles) at a varied distance below. In some, this division is blurred and, in thecates, there is a single whorl which has been held to represent the two athecate whorls merged. See also oral. (Cornelius, 1995 a)