1. Fishes

2. Vertebrate Evolution Oldest known vertebrate fossils
Tadpole – like (6inches in length)
Jawless fish were only vertebrates for more than 50 m.y.a

3. Vertebrates (Subphylum Vertebrata)
Backbone enclosing a nerve cord, or spinal cord
Phylum Chordata
Notochord
Pharyngeal pouches
Postanal tail
Dorsal Nerve Chord

4. Phylum Chordata Subphylum Vertebrata
Super Class Agnatha Jawless fishes
Class Myxini (Hagfishes)
Class Cephalaspidomorphi (Lampreys)
Class Chondrichthyes, Cartilaginous fishes, (Sharks, Sharks and Rays, Ratfishes)
Class Osteichthyes, Bony fishes
Class Actinopterygii (Ray – finned)
Class Sarcophterygii (Lobe – finned)

5. Fig. 8.1

6. Tab. 8.1

7. Class Agnatha: Jawless Fishes
Hagfishes and lampreys
lack jaws, most primitive of living fishes
Feed by suction
Lack paired fins and scales
Hagfish (slime eels)
No vertebrae
Retains notochord
Lampreys, freshwater
Primitive Vertebral column composed of cartilage

8. Origin of Jaws and Paired Fins
450 m.y.a
Paired fins increased fishes’ stability and maneuverability
Jaw allow to seize prey
Jaws are thought to have evolved from 1st pair of gill arches (support pharynx)

9. Class Chondrichthyes: Cartilaginous Fishes
Sharks, rays, skates, and ratfishes
Endoskeleton of cartilage
Paired fins, movable jaws, gill slits
Rough sandpaper – like skin
placoid scales
pointed tip that is directed backward
same composition as teeth

10. Fig. 8.4

11. Super Class Osteichthyes: Bony Fish
Largest group of living vertebrates
Gills covered by operculum
Usually swim bladder
Highly maneuverable fins
Cycloid scales

12. Superclass Osteichthyes: Bony Fish
Class Sarcopterygii (lobed – fin finned)
Class Actinopterygii (ray – finned)

13. Class Sarcopterygii (lobed – fin finned)
Fins supported by main axis of bone
Lungfishes (video)
Modified swim bladder
Breath air

14. Class Sarcopterygii (lobed – fin finned)
Coelacanth
Were thought to be extinct but were rediscovered in West African waters
Coelacanth species are thought to be ancestors of amphibians

15. Class Actinopterygii (ray – finned)
Most common of boney fish