BIOL1002 Lecture Notes - Lecture 7: Swim Bladder, Chondrichthyes, Pharyngeal Jaw
6 Nov 2018
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Document Summary
The approximately 30,000 species of actinopterygii, or ray-finned fishes (most species of any vertebrate lineage), have several morphological features that set them apart from the cartilaginous fish: Fins supported by bony rods arranged in a ray pattern. A gas-filled swim bladder, evolved from the lungs of early fish, used for maintaining buoyancy at varying depths. Cartilaginous fish such as sharks and rays do not have a swim bladder: need to swim to avoid sinking. In the actinopterygii, adding or removing gas from the swim bladder allows the fish to either raise or lower its position in the water (or maintain its position). The swim bladder is homologous to lungs in terrestrial vertebrates. Most important lineage of ray-finned fishes: the teleostei. About 96% of living fish species, including tuna, cod, and goldfish, are teleosts. Feeding: teleosts have protrusible jaws, with teeth, with a a second pair of pharyngeal jaws in the throat.
