part_of part of part of anatomical system viscus swim bladder fish maw air bladder SCTID:64748009 UBERON:0008980 EFO:0003483 gas bladder UBERON:0006860 ZFA:0000076 BTO:0001607 Cavitated compound organ that is double-chambered, located in the coelom and used to maintain buoyancy and may function as an acoustic resonator.[TAO] A thin membranous, sometimes alveolated sac in the dorsal portion of the abdominal cavity. Contains a varying mixture of gases, not identical to the composition of air. May be one, two or three chambered. May be connected to the gut by a tube, the ductus pneumaticus (then called physostomous) or unconnected (then called physoclistous). Lungs had already developed as paired ventral pockets from the intestine in the ancestor of Osteognathostomata. (...) In actinopterygian fishes, apart from Cladistia, the ventral intestinal pocket migrates dorsally and becomes the swim-bladder, a mainly hydrostatical organ (reference 1); Comparative transcriptome analyses indicate molecular homology of zebrafish swimbladder and Mammalian lung (reference 2).[well established][VHOG] swimbladder May function as one or more of: hydrostatic organ, sound producing organ, sound receptor, respiratory organ BTO:0002148 TAO:0000076 Found in Actinopterygii. Often lacking in bottom fishes zebrafish component