BIOL108 Lecture Notes - Lecture 29: Swim Bladder, Chondrichthyes, Ichthys

• School: University of Alberta
• Department: Biology (Biological Sciences)
• Course: BIOL108
• Professor: Lien Luong

Document Summary

Originally class osteichthyes osteo = bone, ichthys = fish skeleton becomes ossified (bony) replacement of cartilage by calcium phosphate. Paraphyletic - if restricted to fish paraphyletic group: includes completely aquatic craniate that uses gills for respiration includes jawless fishes, cartilaginous fishes, and bony fishes, and excludes tetrapods. Yes if we want to make it monophyletic. Don"t though so we consider osteichthyes a paraphyletic group. Extant bony fish descended from fresh or brackish (fresh + salt) water ancestors that had simple lungs and gills simple lung = ventral out-pocketing of foregut with gas augmented gas-exchange by gills. Original lung modified into swim bladder in most extant bony fish. Perform different functions: lungs (paired) -> respiration swim bladders (single) -> provide buoyancy. Both arise developmentally from the same embryonic tissue: lungs and swim bladders developed from out-pocketing of the gut. Other bony fish kept both lugs and gills e. g. lungfish.