ABSTRACT
Molluscan reproductive strategies are some of the most diverse in the Metazoa, and their varied reproductive modes are a rich field of inquiry for ecological and evolutionary studies. Bivalve reproductive system structures are conservative. Gastropod reproductive systems are highly diverse, with the greatest diversity in a single clade – the Heterobranchia. Synchronisation is important in reproduction. In gonochoristic species, male and female gametes must mature simultaneously to prepare for fertilisation and spawning, and in hermaphroditic species, reproductive systems must be controlled sequentially or simultaneously in the same individual. Control of reproduction in coleoid cephalopods is relatively simple and appears to involve only one gonadotropin-releasing hormone-like hormone from one pair of endocrine glands, the neural optic glands. Hox genes are a family of transcriptional regulatory proteins governing embryonic development in molluscs and other Bilateria. Gastropods are unique in undergoing ano-pedal flexure, torsion, and then strong left-right asymmetry in the development of their mesoderm-derived tissue and organ systems.
