INTERSEXUALITY AND ITS CONTROL BY THE ANDROGENIC GLAND IN THE CRAYFISH CHERAX QUADRICARINATUS

摘要

Intersex individuals, possessing both male and female characteristics, have been documented mainly in hermaphrodite species. Intersex characteristics may be limited to the external morphology or may extend to gonadal differentiation. Hermaphroditism-the condition of having both male and female functional reproductive organs in one individual-has been reported for a variety of crustaceans. Some cases of sequential hermaphroditism, in which intersex individuals serve as a transitional form during the process of sex change, have also been reported. Sex changes occur only in a small percentage of crustacean species which are predominantly protandric (change from male to female). Crayfish are generally regarded as gonochoristic, i.e., producing distinctmale and female specimens. However, apparent intersexuality has been reported in several crayfish species. These reports do not facilitate an understanding of the functional sexuality of the specimens or indeed of the species. The two crayfish species inwhich intersexuality has been adequately reported present nonfunctional hermaphroditism, including functional males with immature ovaries in Cherax quadricarinatus (Sagi et al., 1996a), and partial protandric hermaphroditism in Parastacus nicoleti (Rudolph, 1995).