How many different kinds of shellfish are there?

How many kinds of shellfish is there?lots of shellfish

Some types include:

banana prawn, sand crab, clam, cockle, crab, crayfish, lobster, Dublin bay prawn, freshwater shrimp, king prawn, langoustine, Moreton Bay bug, mud crab, mussel, oyster, scallop, soldier crab, school prawn