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Zoology Notes # 6

Zoology Notes # 6. FISH!!. Big Idea: Continuing Evolutionary History…. From invertebrates… to vertebrates…. Quick Question #1: What are some characters shared between different clades below?. Our first focus…FISH. Quick Question #2.

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Zoology Notes # 6

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  1. Zoology Notes #6 FISH!!

  2. Big Idea: Continuing Evolutionary History… From invertebrates… to vertebrates…

  3. Quick Question #1: What are some characters shared between different clades below? Our first focus…FISH

  4. Quick Question #2 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. Quick Question #3 Thinking about the three types of fish, draw a cladogram with how they could be classified. Explain why you chose it.

  8. 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

  9. 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

  10. Cartilaginous Fish (Chondricthyes) • Chondrosmeans 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!

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

  12. Quick Question #3 Thinking back to Zoology Notes number 4, what are the 3 big questions we want to think about for every group of animals we are going to be discussing.

  13. 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)

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

  15. 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

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

  17. How do they Survive:Respiration • Most breathe with gills • Gills contain many capillaries, allowing for maximum exchange of O2 and CO2 • Dissolved gasses are sometimes stored in a swim bladder, a sac that lies on top of the body cavity and is used for buoyancy

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

  19. Quick Question #4 Ex Explain how blood and gas exchange within a fishes circulatory system.

  20. 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

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