What is a swim bladder?
Q: What is a swim bladder?
A: A swim bladder is an internal gas-filled organ in bony fish that helps them control their buoyancy.
Q: How does a swim bladder help bony fish?
A: Fish with a swim bladder can stay at their current water depth without having to waste energy in swimming.
Q: What is the dorsal position of the swim bladder?
A: The dorsal position of the swim bladder means the center of mass is below the center of volume, so it acts as a stabilizing agent.
Q: What is the swim bladder's function as a resonating chamber?
A: The swim bladder is a resonating chamber, to produce or receive sound.
Q: What is the evolutionary relationship between swim bladders and lungs?
A: Swim bladders are evolutionarily closely related (i.e., homologous) to lungs.
Q: What allowed fish to gulp air in oxygen-poor conditions?
A: The first lungs (simple sacs connected to the gut) allowed the fish to gulp air in oxygen-poor conditions.
Q: What did lungs evolve into?
A: Lungs evolved into the lungs of today's terrestrial vertebrates and some fish (lungfish, gar, bichir) and also into the swim bladders of the ray-finned fishes.
