1. General description of oysters

From a shellfish farming point of view, marine animals are classified into four families: crustaceans with an external chitinoprotein skeleton or exoskeleton (crab, lobster, spider...), cephalopod mollusks with a soft body (squid, cuttlefish, octopus...), non-cephalopod mollusks including bivalves, with two valves connected by a ligament along the hinge, such as oysters, and gastropods with a soft body (gastropods...).), non-cephalopod molluscs including bivalves, which have two valves connected by a ligament along the hinge, such as oysters, and gastropods, which have a spiral shell with an external foot for movement, as well as invertebrates (sea urchins, violet and holothurians).

Shellfish are not crustaceans, but mollusks that live in the sea. The best-known are oysters, mussels, clams, whelks, sea almonds, abalone, clams, razor clams, scallops and scallops....