∞ generated and posted on 2016.11.12 ∞
Gas-filled buoyancy-control organ associated with osteichthyans.
Depending on the species, and means of filling, the swim bladder can be filled either with air or, instead, with oxygen. Air is obtained by gulping whereas oxygen is generated by associated gas glands.
The lungs of tetrapods as well as lobe-finned fish are modified swim bladders (i.e., our lungs and swim bladders are homologous structures).