air bladder

American  

[air blad-er] / ˈɛər ˌblæd ər /

noun

1. a vesicle or sac containing air.

2. Also called swim bladder.  Also called gas bladder,.  Ichthyology. a gas-filled sac located against the roof of the body cavity of most bony fishes, originally functioning only as a lung, now serving in many higher fishes to regulate hydrostatic pressure.

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air bladder British  

noun

1. Also called: swim bladder.  ichthyol an air-filled sac, lying above the alimentary canal in bony fishes, that regulates buoyancy at different depths by a variation in the pressure of the air

2. any air-filled sac, such as one of the bladders of seaweeds

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air bladder Scientific  

1. An air-filled sac in many fish that helps maintain buoyancy or, in some species, helps in respiration, sound production, or hearing.

2. Also called swim bladder

3. See float

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Etymology

Origin of air bladder

First recorded in 1725–35

Example Sentences

Otophysan fish improved this pathway by adding small bony "ossicles" that connect the air bladder, often mistakenly called the swim bladder, to the inner ear.

From Science Daily • Nov. 3, 2025

Many fish therefore evolved an internal air bladder that vibrates with passing sounds.

From Science Daily • Nov. 3, 2025

They’re a long, thin fish that can breathe air through an air bladder like a lung and can live up to four days out of water if they’re kept moist, experts said.

From Washington Post • Jul. 6, 2022

The laces had to be undone before an interior air bladder was filled and tied with a thread; then the laces were retied.

From New York Times • Jun. 12, 2014

This effect has been attributed to the escape of air from the air bladder, but no air bladder has been found in the Cottus, which makes a similar noise.

From Sketches of the Natural History of Ceylon by Tennent, James Emerson, Sir