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The Chordates

The Chordates. Chapters 30-32 Biology – Miller • Levine. Chordates. Phylum Chordata Includes two invertebrate subphyla: lancelets and tunicates Subphylum Vertebrata. Chordate Characteristics. Dorsal, hollow nerve cord – the brain and spinal cord

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The Chordates

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  1. The Chordates Chapters 30-32 Biology – Miller • Levine

  2. Chordates • Phylum Chordata • Includes two invertebrate subphyla: lancelets and tunicates • Subphylum Vertebrata

  3. Chordate Characteristics • Dorsal, hollow nerve cord – the brain and spinal cord • Notochord – flexible, longitudinal rod located between the digestive tract and the nerve cord • Pharyngeal pouches – gill structures in the pharynx • Post-anal tail – tail to the rear of the anus

  4. Chordate Characteristics • The characteristics are not always visible in the adult form, but are always present in the embryo

  5. Vertebrates • Subphylum that includes mammals, birds, reptiles, amphibians and the various classes of fishes • Unique features include cranium and backbone

  6. Fishes

  7. Agnathans • Jawless fish • Class Myxini (hagfishes) • Class Cephalaspidomorphi (lampreys)

  8. Class Chondrichthyes • Cartilaginous fishes • Include sharks and rays • Have a flexible skeleton made of cartilage • Lateral line system – row of sensory organs running along each side of the body, detects minor vibrations

  9. Class Chondrichthyes

  10. Class Osteichthyes • Bony fishes (trout and goldfish) • Also have a lateral line system • Operculum – protective flap that covers the gills • Swim bladder – gas-filled sac that keeps them buoyant

  11. Class Osteichthyes • Most are ray-finned fishes – fins supported by thin, flexible rays • Lungfishes – must surface to gulp air into their lungs • Lobe-finned fishes – fins are supported by stout bones

  12. Amphibians

  13. Class Amphibia • Frogs and salamanders • Exhibit a mixture of aquatic & terrestrial adaptations • Need water to reproduce • Depend on their moist skin to supplement lung function in exchanging gases

  14. Class Amphibia • First vertebrates to colonize land • Tetrapods (“four legs”) – terrestrial vertebrates (amphibians, reptiles, birds & mammals)

  15. Reptiles

  16. Class Reptilia • Snakes, lizards, turtles, crocodiles, and alligators • Have many additional adaptations for living on land • Water-proofed scales to prevent dehydration • Amniotic egg – water-containing egg enclosed in a shell

  17. Class Reptilia • Ectotherms – warms itself by absorbing external heat • Can survive on less than 10% of the calories required by mammals • Mesozoic era – “age of reptiles” – the time of the dinosaurs

  18. Birds

  19. Class Aves • Birds • Reptilian features – scales on legs, amniotic egg • Almost all species are able to fly

  20. Class Aves • Adaptations for flight: • Light, hollow bone • Absence of some internal organs • Are toothless • Endotherms – maintain temperature using metabolic heat • Wings – strong muscles, feathers

  21. Mammals

  22. Class Mammalia • Probably evolved from reptiles • Most are terrestrial, some are aquatic (dolphins, whales), some can fly (bats) • Two unique features: hair and mammary glands • Are endotherms • Have a fluid filled amniotic sac

  23. Three Major Groups • Monotremes – egg-laying mammals (platypus) • Marsupials – pouched mammals (kangaroo) • Eutherians – placental mammals • Make up almost 95% of mammals • Marsupials and Eutherians both have a placenta which joins the embryo to the mother and provides nutrients to the embryo

  24. Class Mammalia

  25. Primates • Order that includes monkeys, apes & humans • Early primates were small, arboreal (tree-dwelling) mammals • Limber shoulder joints, dexterous hands, eyes close together on face, excellent hand-eye coordination

  26. Primates • Divided into two main groups: • Prosimians (lemurs) • Anthropoids (monkeys, apes & humans) • Humans are most closely related to apes

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