| I: | They have four pairs of gills which are covered by an operculum on each side. |
| II: | Due to the absence of air bladder, they have to swim constantly to avoid sinking. |
| III: | Skin is covered with placoid scales. |
| IV: | Mouth is mostly terminal. |
| 1. | Only II | 2. | Only II and III |
| 3. | Only I and IV | 4. | Only IV |
| 1. Angel fish | 2. Flying fish |
| 3. Star fish | 4. Fighting fish |
| 1. endotherms | 2. marine fishes |
| 3. protochordates | 4. bony fishes |