As compared to cartilaginous fishes, bony fishes have ........... dorsal fin.
Single instead of two
Two instead of one
Single in both
Two in both
The correct option is A Single instead of two
Dorsal fins are located at the back of the body of the fish. These fins help the fish in turning and stopping. Cartilaginous fishes belong to class Chondrichthyes and have paired fins. Hence, they have two dorsal fins. On the other hand, bony fishes belong to class Osteichthyes and have a single dorsal fin.
So, the correct answer is 'Single instead of two'.