ABSTRACT
Among vertebrates, the existence of simultaneous hermaphrodism is a big puzzle. There are three kinds of simultaneous hermaphrodites: 1. Selffertilizing hermaphrodites, 2. Gamete exchanging hermaphrodites and 3. Potential self-fertilizing hermaphrodites. The presence of the third group is based on recent reports on the occurrence of simultaneous hermaphroditism in Chlorophthalmus, Bathypterois, Benthalbella and Bathysaurus (see Sadovy de Mitcheson and Liu, 2008) and a few muraenids (Fishelson, 1992). The fi rst group is represented by a single species Rivulus marmoratus (Cyprinodontidae) and the latter by a few species belonging to the genera Serranus and Hypoplectrus (Serranidae). These hermaphrodites possess functional distinct ovary and testis, and their corresponding ducts to release gametes or fertilized embryos (R. marmoratus). Though they are limited to only a few species, their very existence poses many challenges to geneticists and endocrinologists. Information on their general biology is available; molecular biologists have made an attempt to understand the sustenance of different clones of R. marmoratus; behaviour specialists have described the mating and mating system of serranids. However, the puzzling simultaneous hermaphrodites seem to have long remained unnoticed and unattended by endocrinologists and geneticists.
