3. Our first focus…FISH

4. In your own words, describe what makes a fish a fish.

5. What Is A Fish? Definition: aquatic vertebrates that are characterized by scales, fins, and gills Have a cranium (skull) Lack limbs or digits

6. Types of Fish 3 main groups of fishes: Jawless fish Ex: hagfish Cartilaginous fish Ex: sharks Bony fish Ex: puffer fish

7. Thinking about the three types of fish, draw a cladogram with how they could be classified. Explain why you chose it.

9. Evolution of Fishes Jawless fishes with heavy armor (bony plates) Then came the fishes with jaws (an important evolutionary innovation!) Then came paired appendages (pectoral and pelvic fins) Then came the cartilaginous and bony fishes

10. Jawless Fish (Agnatha) Lampreys Filter feeders as larvae, parasites as adults Head is a round sucking disk with a mouth in the middle Hagfish Worm-like bodies with 4-6 short tentacles around the mouth Only a light-detecting region, no eyes They use a toothed tongue to scrape holes into dead or dying fish for food They secrete tons of slime http://www.youtube.com/watch?v =bqk0mnMgwUQ http://www.youtube.com/watch?v =bqk0mnMgwUQ

11. Cartilaginous Fish (Chondricthyes) Chondros means cartilage, icthyes means fish Toothlike projections all over their cartilaginous skin (act like scales and aide in swimming) Multiple rows of teeth A typical shark may go through 20,000 teeth in one lifetime!

12. Bony Fishes (Osteichthyes) ~40% of all vertebrates are bony fishes

13. What are the 3 big questions we want to think about for every group of animals we are going to be discussing.

14. How do they Reproduce? Most are oviparous (egg layers) with external fertilization Some have internal fertilization and lay fertile eggs (sharks) Varied parental care (from non- existent to utmost importance) Some fish are ovoviviparous (young develop inside the mother’s body but are not nourished directly by the mother’s body) Still others are viviparous (species that bear living young and have unborn young that are nourished directly by the mother’s body)

15. How do they eat: Feeding Variety of feeding mechanisms Herbivores carnivores parasites filter feeders detritus feeders Many fish do more than one

16. Digestion Food goes from the mouth to the esophagus, to the stomach where it is broken down In some fish, the broken down food can go to fingerlike pouches at the point where the stomach and the intestines meet called pyloric ceca Any other undigested food gets passed through the anus as waste

17. Excretion Fish excrete nitrogenous waste in the form of ammonia through gills and kidneys Osmoregulation: Freshwater fish Saltwater fish

18. How do they Survive: Respiration Most breathe with gills Gills contain many capillaries, allowing for maximum exchange of O 2 and CO 2 Dissolved gasses are sometimes stored in a swim bladder, a sac that lies on top of the body cavity and is used for buoyancy

19. How do they survive: Internal Transport Closed circulatory system Two-chambered heart (atrium, ventricle)

20. Ex Explain how blood and gas exchange within a fishes circulatory system.

21. How do they Survive: Response Well-developed nervous system organized around a brain Spinal cord (hollow dorsal nerve cord) lies behind the brain and may be protected by a vertebral column Chemoreceptors and electrical detectors may aid in strong sensory perception in some fish