Bivalves are widespread invertebrates that are mostly marine and benthic, with great impacts in the aquatic systems food chains. Their soft body is laterally compressed and covered with a hard shell, often having bilateral symmetry. Strong adductor muscles help in the shell movement. Various species are used as bioindicators of environmental quality. Many, such as mussels, clams, scallops, or oysters, are heavily harvested/reared for human consumption. Bivalves availability, adaptability and simple anatomy make them attractive for both fundamental and applied research. One particular target for such studies is the nervous system. It is typically made of  a central nervous system holding three types of ganglia (cerebral, pedal, visceral), organized into an outer neuron- and glia-rich cortex and an inner axon-rich medulla. Nerves interconnect the ganglia as well as these and peripheral nervous system components, made of sensorial structures such as eyes (mantle, tentacles), and osphradia (gills) and statocysts (foot); They are involved in photoreception or are mechano or chemoreceptors. Among other roles, the nervous system governs reproduction, via influences in the sexual development, gametogenesis, fertilization and spawning. Such modelling is via neurotransmitters and neurohormones, interplaying with direct/indirect impacts of biotic (eg, food abundance) and abiotic (eg, temperature, pH, salinity) factors. We know now that many pollutants can disrupt the nervous system and gonads and their poorly known interaction. Knowing the nervous system functional morphology is critical to understand such disruptions and foreseen reproductive consequences. Accordingly, this work offers a systematic overview about the bivalve nervous system and related reproductive events.

Keywords: Anatomy; Histology; Bivalves; Nervous system; Ganglia; Neurons; Glial cells; Neurocytology; Neurophysiology; Reproduction.