1. Copyright Pearson Prentice Hall 30-2 Fishes

2. Copyright Pearson Prentice Hall What Is a Fish? Fishes are aquatic vertebrates. Most fishes have paired fins, scales, and gills. Anal fin Eye Mouth Dorsal fin Caudal fin Operculum (gill cover) Pelvic fin Pectoral fin Lateral lineScales

3. Copyright Pearson Prentice Hall Evolution of Fishes The First Fishes The earliest fishes to appear in the fossil record lived about 510 million years ago. These fishes were jawless and had bodies covered with bony plates.

4. Copyright Pearson Prentice Hall Evolution of Fishes The Arrival of Jaws and Paired Fins The evolution of jaws in fish was extremely useful. Jaws with muscles and teeth made it possible for fish to eat a wider variety of foods. Animals with jaws can also defend themselves by biting.

5. Copyright Pearson Prentice Hall Evolution of Fishes The Rise of Modern Fishes Early jawed fishes soon disappeared, but left behind two major groups that continued to evolve and still survive today. One group—the ancestors of modern sharks and rays—evolved a skeleton made of strong, resilient cartilage. The other group evolved skeletons made of true bone.

6. Copyright Pearson Prentice Hall Form and Function in Fishes Fishes use their gills to exchange gases by pulling oxygen-rich water in through their mouths, pumping it over their gill filaments, and pushing oxygen-poor water out through openings in the sides of the pharynx. Gills

7. Copyright Pearson Prentice Hall Form and Function in Fishes Body muscle circulation Brain and head circulation Heart Digestive system circulation Gills Circulation in a Fish

8. Copyright Pearson Prentice Hall Form and Function in Fishes Many bony fishes have an internal, gas- filled organ called a swim bladder that adjusts their buoyancy. Swim bladder

9. Copyright Pearson Prentice Hall Groups of Fishes All living fishes can be classified into three groups: jawless fishes, cartilaginous fishes, and bony fishes. Groups of Fishes

10. Copyright Pearson Prentice Hall Jawless Fishes Jawless fishes have no true teeth or jaws. Their skeletons are made of fibers and cartilage. They lack vertebrae, and keep their notochords as adults. Groups of Fishes

11. Copyright Pearson Prentice Hall Modern jawless fishes are divided into two classes: lampreys and hagfishes. Lamprey Groups of Fishes

12. Hagfish Copyright Pearson Prentice Hall Hagfish

13. Copyright Pearson Prentice Hall Sharks and Their Relatives The class Chondrichthyes contains sharks, rays, skates, sawfishes, and chimaeras. The skeletons of these fishes are built entirely of cartilage. Groups of Fishes

14. Pacific Manta Ray Copyright Pearson Prentice Hall

15. Bony Fishes Bony fishes make up the class Osteichthyes. Their skeletons are made of bone. Almost all living bony fishes are ray-finned fishes. “Ray-finned” refers to the slender bony spines, or rays, that are connected by a thin layer of skin to form the fins. Groups of Fishes

16. Bony Fish Copyright Pearson Prentice Hall