1. Fish Evolution Part 2

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

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

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

8. Neotany Egg

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

10. Amphioxus Fish Firsts Notochord –Prevents “telescoping” Notochord –Prevents “telescoping”

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

12. Amphioxus Fish Firsts Notochord –Prevents “telescoping” –Hanger for organs Notochord –Prevents “telescoping” –Hanger for organs

13. Notochord

14. Amphioxus Fish Firsts Notochord –Prevents “telescoping” –Hanger for organs Hollow nerve cord Notochord –Prevents “telescoping” –Hanger for organs Hollow nerve cord

15. 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

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

17. W-Shaped Myotomes More Efficient Swimming

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

19. Are they Fish?

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

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

23. Cephalaspids: Organs for hearing or electrical fields?

26. Drepanaspis Cephalaspis

27. Logania

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

32. Relict Species Hagfish Lamprey

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

34. Relict Species Hagfish Lamprey

45. The Opposition

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

51. Invertebrates !

52. Invertebrates Stepped it up a notch

53. Opponents got Tougher

55. Really Tough… Parastylonorus

58. Modern Fish Early Fish Modern Inverts

59. The neighborhood got rougher! Most ostrachoderms were out-competed Only those in specialized niches survived

62. Lamprey, Hagfish, Ostracoderms

63. Jaws Evolved from Gill Arches

66. Dunkleosteus (placoderm)

67. Placoderms Ancestors of Sharks, rays, chimeras 300-400 mya Jaws, paired fins, lungs, gill arches

74. Relicts Seven Gill Shark Ratfish

75. Fancier Jaws

77. There are many relict shark, ray, and chimera species because… Jaws and teeth help make them better able to hunt and defend themselves, then and now Paired fins make them better able to hunt and defend themselves, then and now It worked 350 MYA and it still works now!

79. Acanthodians 440 mya Bony skeleton, jaws, gills Paired fin evolution

86. Lobefins: Coelacanth

89. Acanthostega

93. Acanthostega Late Devonian (350 mya) eight fingers and toes Fish-like features –Gill-bars like a fish –No true elbows, knees, wrists or ankles (not weight-bearing) –Long fin rays around the tail Tetrapod-like features –Head not joined to shoulder girdle –Ear-bone (stapes) fits into fenestra (ovalis/vestibuli) in braincase –Large pelvic girdle, sacral rib –Femur as large as humerus –Tibia and fibula attached to ‘ankle’ bones –Digits on each limb

95. Major moments in fish evolution Amphioxus, the un-missing link –Hollow nerve cord –Notochord –W-shaped myotomes Ostrachoderms, the first true fish Placoderms and Acanthodians –Jaws – Fancier and fancier –Paired fins – Fancier and fancier Descendants of the lobefins conquer land

96. Ancestral Tunicate Amphioxus Ostracoderms Placoderms Acanthodians Lobefins reptiles (Neotany) Hagfish Shark Ray Bony Fish Coelacanth 600 mya 400 mya 150 mya Notochord Nerve Chord Fins Eyes Armor Lungs Paired fins Jaws Bony skeleton

97. Neotany: What is it, how did it give rise to the first primitive fish-like critter (Amphioxus) Amphioxus: What are the important fish-like innovations (w-shaped myomeres, hollow nerve cord, notochord) Ostracoderms: Characteristics and where they fit in fish evolution Placoderms: Characteristics and where they fit in fish evolution Acanthodians: Characteristics and where they fit in fish evolution Fish evolution slide