Sexual Biology and Mating Behaviour in Decapod Crustaceans: A Case Study with Coral Reef-Dwelling Caridean Shrimps

Crustaceans have diversified sexual systems, incorporating various reproductive modalities such as gonochorism and a wide variety of hermaphroditism. In particular, the coral reef- dwelling caridean shrimps, living in symbiosis with other marine invertebrates, have developed unusual sexual systems that have given origin to a range of social systems, including the highly advanced eusociality. Protandric hermaphroditism, common among the caridean shrimps, has also reached a unique sexual condition, known as protandric simultaneous hermaphroditism, in the genus, Lysmata. Similarly, mating systems in the caridean shrimps are highly diverse and divergent. In addition, their occurrence in the coral reef shrimps is correlated to their life style adaptations such as their commensal association with other invertebrates. Other ecological factors like the predation risk from outside of the host animals and differences in the host characteristics may also be the driving forces in determining mating associations. Furthermore, the transition from sexual monogamy to social monogamy under conditions of their symbiotic life led to complex community living in several synalpheid shrimps. Understandably, the existence of various sexual and mating systems in these caridean shrimps has a dependence on the eco- social conditions prevalent in the coral reef biota.