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Skelton & Muscles

Skelton & Muscles. Hagfish. No true vertebrae - sheath of cartilage surrounding notochord Few skull bones. Lamprey skeleton. Cartilaginous limited skull branchial basket. Chondrichthyes skeleton. Cartilaginous limited skull - 3 parts (chondrocranium, jaws, branchial cartilages).

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Skelton & Muscles

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  1. Skelton & Muscles

  2. Hagfish • No true vertebrae - sheath of cartilage surrounding notochord • Few skull bones

  3. Lamprey skeleton • Cartilaginous • limited skull • branchial basket

  4. Chondrichthyes skeleton • Cartilaginous • limited skull - 3 parts (chondrocranium, jaws, • branchial cartilages)

  5. Chondrichthyes skeleton • Cartilaginous • Pectoral, pelvic girdles, fin support

  6. Osteichthyes skeleton

  7. Osteichthyes skeleton • Solid bone with complete vertebral column • Simple vertebrae that lack interlocking processes • One vertebra per body segment - match with muscle masses for coordinated swimming movements

  8. Osteichthyes skeleton Vertebrae modified anteriorly for skull articulation, posteriorly for caual fin articulation

  9. Specialized anterior vertebrae

  10. Posterior vertebrae

  11. Better view of posterior vertebrae

  12. Trunk vertebrae Vertebrae in middle are trunk vertebrae of two kinds: those with ribs and those without

  13. Vertebrae • Vertebrae without ribs • Dorsal process • Neural arch with neural spine • Neural canal for spinal cord

  14. Vertebrae • Ventral process • Hemal arch with hemal spine • Hemal canal for primary blood vessels (arteries, veins)

  15. Spines provide support • Neural and hemal spines provide support for body musculature • Especially long in laterally compressed teleost fishes • “Double comb” appearance

  16. Vertebrae • Vertebrae with ribs extending ventrally and dorsally • Extend between adjacent muscle masses • Dorsal ribs well developed in pike, suckers, minnows

  17. Nice photo

  18. Vertebrae in various fishes

  19. Osteichthyes skull

  20. Osteichthyes skull • >50 bones comprising 5 “groups” • Neurocranium • Suspensorium • Jaws • Opercular bones • Branchiohyoid apparatus

  21. Neurocranium • Braincase • Most of the bones • Core of solid bone around the brain plus loosely articulated bones to permit feeding (suction) and respiratory (pump) movements

  22. Suspensorium • Bones that connect (“suspend”) the braincase to the jaws

  23. Jaws • Upper and lower jaws • Change from stiff, biting mouth to flexible, sucking mouth • Maxilla (primitive), premaxilla (advanced), dentaries

  24. Opercular bones • No equivalent in jawless fishes or Chondrichthyes • Primary role in respiratory pumping • Advancements (from primitive condition) small, centered on improving efficiency

  25. Branchiohyoid apparatus • Floor of the mouth, support for the gills • Includes the branchiostegal rays • Function in expansion of branchial chamber for respiration, suction feeding

  26. Advanced fish skull

  27. Pectoral, pelvic girdles

  28. Pectoral girdle • Fin rays articulate with radial bones (usually 5 radials) • Radials articulate with scapula, coracoid • These articulate with cleithrum, others • Cleithrum attached to skull

  29. Pelvic girdle • Fin rays articulate with basipterygial bone • Basipterygials either united with each other, or with cleithrum/pectoral girdle complex in more derived teleosts

  30. Dorsal, anal fin support Pterygiophores or interspinous bones

  31. Fish musculature

  32. Segmental muscles -Right and left sides separated by vertical septum -Dorsal and ventral masses separated by horizontal septum

  33. Epaxial, hypaxial muscles • Above horizontal septum - epaxials • Below horizontal septum - hypaxials

  34. W-shaped myotomes

  35. Red vs. white muscles -Red - rich in blood supply - aerobic swimming (slow) -White - poor in blood supply - burst swimming (fast) -Pink - intermediate -Color may be diet-based (carotenoids/crustaceans)

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