BIOL 330 Lecture Notes - Lecture 6: Ocean, Jellyfish, Fish Head
14 Feb 2017
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Document Summary
All extant tetrapods are derived from ancestral bony fishes. Specialization of feeding mechanisms and locomotion: sarcopterygii lobe-finned fishes (fleshy- finned fishes, rays of paired fins extend from a central shaft of bones in a leaf- like manner to support fin web. Tetrapods: actinopterygii ray-finned fishes, rays spread out like a fan of bones at the base of the fins. Endochondral bone (bone that replaces cartilage ontogenetically unique to bony fishes) * unique pattern of dermal bone around jaws and braincase. Autostylic jaws (upper jaw attached directly to skull via bone stronger bite, less gape) *note: agnathans have bones; cartilage in chondrichthyans is derived. Dorsal, caudal, anal fins: one continuous fin. Australian lungfish: gills, use lungs only when stressed. South american/african lungfishes weakly developed gills; depend on breathing air with lungs. Induced by heat or drying of habitat (analogous to hibernation) In dry seasons, borrow in bottom mud; folding into a u-shape; mucus forms protective envelope.
