1. Phylum Chordata Subphylum Vertebrata common characteristics • internal skeleton of cartilage or bone • dorsal nerve cord surrounded by vertebrae • bony cranium encompassing a complex brain • notochord only in embryo Nine Living Classes • 5 classes of fishes • Class Amphibia • Class Reptilia • Class Aves • Class Mammalia

2. The Fishes Pikaia: first fossil vertebrate (580 m.y.a.) Superclass Agnatha Fishes Without Jaws Class Myxini Hagfishes Class Petromyzontida Lampreys

3. Fishes Without Jaws Body eel-like, no paired appendages Fibrous, cartilaginous skeleton (no vertebrae) Heart with one atrium, one ventricle External fertilization Gonads of both sexes in each individual (but only one sex functional)

4. Class Myxini hagfish • marine • scavengers • partial cranium • great sense of smell • no sense of sight

5. Feeding rasping tongue and sliding knot

7. Class Petromyzontida lampreys • free-swimming parasites/predators • sucker-like mouth • reproduce in streams, migrate to sea (or lakes)

8. Fish Parasites

9. Eggs in gravel nest in stream riffle Adult lamprey attached to host fish Larvae drift downstream to muddy backwater Metamorphosis and migration to lake or sea Worm-like larvae in mud 5+ years

10. The Fishes Superclass Gnathostomata Fishes With Jaws Class Chondrichthyes Cartilaginous Fishes Class Actinopterygii Ray-finned Fishes Class Sarcopterygii Lobe-finned Fishes

11. Evolution of the Jaws Modification of existing structures to perform new functions

12. Vertebrates with Jaws Superclass Gnathostomata strong jaws armored with heavy plates paired pectoral & pelvic fins First Jawed Fish = Placoderms

13. Further modifications for more efficient function

14. Cartilaginous Fishes Class Chondrichthyes Skates, Rays, and Sharks • 5 to 7 gill slits • no gill covers • placoid (toothlike) scales • filter feeders or predators

16. Bony Fishes (The Osteichthyes) Class Sarcopterygii (lobe-finned fishes) Class Actinopterygii (ray-finned fishes) • operculum over gill slits • bony skeleton • dermal scales • swim bladder

17. Fish Circulatory System

18. Fish Respiration Counter Current Circulation Same Direction Flow Countercurrent Flow

19. Swim Bladder

20. Anadromous Reproduction

21. Class Actinopterygii Ray-finned Fishes • radiating supports in fins • filter feeders or predators • dermal scales (formed of bone)

22. Evolution of The Tetrapods Two Hypotheses • Lobe-finned fishes capable of moving from pond to pond • Abundant food (and absence of predators) on land

23. Class Sarcopterygii Lobe-finned Fishes • strong, fleshy fins • fins supported by central (not radiating) bones • heavy, enameled scales