For many fish, the swim bladder has the additional role of transferring sound waves to the auditory system. And in some fish, such as drums and croakers, the swim bladder is used to make sounds and communicate with one another and other fish. Fish use swim bladders for buoyancy, hearing, and producing sounds.

Which animals use swim bladder?

Swim bladder, also called air bladder, buoyancy organ possessed by most bony fish.

What are swim bladders used for?

The swim bladder is a gas-filled organ in the dorsal coelomic cavity of fish. Its primary function is maintaining buoyancy, but it is also involved in respiration, sound production, and possibly perception of pressure fluctuations (including sound).