Oysters and Scallops

General Diagram of a Bivalve Nervous System

The nervous system of Oysters and Scallops like most Bivalves is rather simple. They have around three ganglia, which control the muscles of the animal. Though they have no no sensory organs they do have sensory cells, and are capable of reacting to sensations like touch. The scallop, unlike the oyster, has eyespots as well.

Both Oysters and Scallops can be  hermaphroditic. They have two gonads, one which houses the testis, and the other which houses the ovaries. Gametes are released from the animal into the water, and fertilization takes place externally. Even if the Oyster or Scallop is not hermaphroditic ,though most of them are, then fertilization will sill take place externally.Oysters spawn year round and can have from 1 to millions of eggs depending on the species.