FNR 24150 Study Guide - Final Guide: Alligator Gar, Fish Scale, Piscivore
16 Oct 2017
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Far: fishes final exam: evolution and systematics, 4 fish classes. Features: cosmoid scales- overlapping, fusion of placoid scales. Lobe fins- single bone or line of bones for support, joined to body by a single bone: gave rise to tetrapods. Tiktaalik- discovered in 2004, pectoral fin girdle could support weight on land, eyes on top of head (extinct: crossopterygii (coelacanths) Thought to have gone extinct 65 mya, rediscovered in1938, critically endangered: dipnoi (lungfishes) Found in australia, africa, and south america fresh waters. Massive tooth plates, do not breathe with gills (have lungs: actinopterygii: ray-finned fishes. Possess lungs like sarcopterygii, but has ray fins, egg structures and genetic similarities in common with. 2 genera with 12 extant species: acipenseriformes (sturgeons- 25 species and paddlefish-2 species) Cartilaginous skeleton, ancestral forms ossified and highly derived. Sturgeons: 4 barbels, 5 rows of scutes (large bony shields) Paddlefish: mostly scale-less, can detect electrical fields made by prey: lepisosteiformes (gars and allies)
