10. How important is the presence of air bladder in Pisces?
The air bladder is found to be present in the members of class Osteichthyes while it is absent in Chondrichthyes. The main function of air bladder is to regulate buoyancy and help the fishes to float in the water. It also prevents them from sinking in the water. Since Chondrichthyes do not have air bladder they have to swim continuously to avoid sinking.