(a) Types of Shell Fish (i) Cockles (ii) Oysters (iii) Scallops (iv) Shrimps (v) Clams (vi) Lobsters (vii) Crabs (vii) Prawns (ix) Crayfish (x) Mussels (xi) Periwinkles (xii) Crustaceans (xiii) Mollusca/ Molluscs.
(b) on the three classes of fish (i) Oily Fish - Oily fish have oil distributed all over their bodies and are mostly dark in colour. (ii) White Fish: - White fish or lean fish have most of their fat deposited in the liver and are mostly white in colour. (ii) Shell Fish: They have a protective covering of shell. They are of two groups: Molluscs and Crustaceans.