EEB267H1 Lecture Notes - Lecture 7: Barotrauma, Hyomandibula, Parrotfish
26 Jan 2017
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3 types of gas bladders in ray-finned fishes. Pneumatic duct: direct connection between the mouth and gas bladder, pneumatic duct muscles control intake/outtake of gas. Deflate bladder by spitting out bubbles of air. Note: larvae (of all physostomous and some physoclistous) must get to surface and fill up gas bladder the first time: extremely high predation. No longer a connection between gas bladder and esophagus: no pneumatic duct. Individual gas cells form a gland in the gas bladder the gas gland. Filling gas bladder same process as before: gas gland secretes lactic acid into the rete, oxygen released from blood and diffuses itno gas bladder. Takes more time to empty bladder: slow process. Benefit: immense saving in energy (no longer have to swim to change depth in water or swim continuously to avoid sinking) Cost: difficult to move vertically over great distances quickly because the gas bladder takes time to inflate/ deflate (oxygen/lactic acid moves by diffusion)
