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Fish Evolution Part 2

Fish Evolution Part 2. * Fish were the first vertebrates * Tunicates link the invertebrates and vertebrates. Water In. Ganglion. Gill Bars. Water Feces Ova Out. Heart. Water To Exit. Gonads. Tunicate Anatomy. Eye Spot. Nerve Cord. Tunicate Life Cycle. Free-Swimming Larva.

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Fish Evolution Part 2

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  1. Fish EvolutionPart 2

  2. * Fish were the first vertebrates * Tunicates link the invertebrates and vertebrates

  3. Water In Ganglion Gill Bars Water Feces Ova Out Heart Water To Exit Gonads TunicateAnatomy

  4. Eye Spot Nerve Cord Tunicate LifeCycle Free-Swimming Larva Mouth Notochord Gill Slits Egg Metamorphosis

  5. Neotany Egg Egg

  6. Fish Evolution Amphioxus Modern Fish Primitive Chordate Via Neotany Arm Feeder Ancestral Tunicate Gill Feeder Modern Tunicate

  7. Amphioxus Fish Firsts • Notochord • Prevents “telescoping”

  8. Amphioxus Notochords Telescoped Amphioxus No Notochord Blue Muscle Contraction Swimming Amphioxus With Notochord

  9. Amphioxus Fish Firsts • Notochord • Prevents “telescoping” • Hanger for organs

  10. Notochord

  11. Amphioxus Fish Firsts • Notochord • Prevents “telescoping” • Hanger for organs • Hollow nerve cord

  12. Nerve Cord Evolution Starfish: A simple network of nerves. Earthworm: A network of nerves connected to ganglia Fish: Hollow nerve cord (spinal cord) and a brain

  13. Amphioxus Fish Firsts • Notochord • Prevents “telescoping” • Hanger for organs • Hollow nerve cord • W-shaped myotomes

  14. W-Shaped Myotomes More Efficient Swimming

  15. Amphioxus Overview Neural Tube Eye Spot Notochord Gills Mouth Fin-Like Flap No Jaws Junky Fins

  16. Are they Fish?

  17. Relict species very similar to the first fish-like animal. • Most important innovations • Notochord • Hollow nerve chord • W-shaped myotomes

  18. What came after that amphioxus like ancestor ?

  19. Ostracoderms • 500-370 MYA • Single nostril • No paired fins • No jaws • Notochord and rudimentary vertebrae • Lungs! • Armor for protection

  20. Cephalaspids: Organs for hearing or electrical fields?

  21. Drepanaspis Cephalaspis

  22. Logania

  23. Logania

  24. Logania

  25. Is there an Ostracoderm like relict species ?

  26. Ostracoderms • 500-370 MYA • Single nostril • No paired fins • Notochord and rudimentary vertebrae • Lungs! • Armor for protection • No jaws

  27. Relict Species Hagfish Lamprey

  28. Ostracoderms Hagfish/Lamprey • Single nostril • No paired fins • Notochord/vertebrae • Lungs! • Armor for protection • No jaws

  29. Relict Species Hagfish Lamprey

  30. Why only 2 Relict species?

  31. The Opposition

  32. The Home Team • No jaws for catching prey • Primitive fin arrangements • Stiff armored bodies

  33. Fish

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