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Vertebrate Diversity

Vertebrate Diversity. Phylum Chordata. Bilateral Deuterostomes 4 characteristics Dorsal, hollow nerve cord Central nervous system Notochord Supports nerve cord, reduced in many vertebrates Pharyngeal slits Filter feeding, gills, parts of ear Post-anal tail. Chordates. Lancelets

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Vertebrate Diversity

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  1. Vertebrate Diversity

  2. Phylum Chordata • Bilateral Deuterostomes • 4 characteristics • Dorsal, hollow nerve cord • Central nervous system • Notochord • Supports nerve cord, reduced in many vertebrates • Pharyngeal slits • Filter feeding, gills, parts of ear • Post-anal tail

  3. Chordates • Lancelets • Muscle structure similar to fish in chevron shape • Tunicates • Only larval stage has chordate characteristics • 9 hox genes instead of 13 like vertebrates • Research on genetic control of brain and nerve formation

  4. Craniates • Head with brain, eyes, nerves • Characteristics • Neural crest becomes teeth and some nerves • Pharyngeal slits become gills • Muscular digestive system to support higher metabolism

  5. Craniates • Hagfishes • Brain and partial skull • No jaws or vertebrae • Marine scavangers • Slime glands to avoid being eaten

  6. Vertebrates • Backbone made of vertebrae • Lampreys- no jaws • Parasites of fish • Problems for Great Lakes

  7. Gnathostomes • Have jaws • Aquatic species have lateral line systems • Sensitive to changes in water pressure • Fossil gnathostomes: placoderms • Armored fish • Dunkleosteus: 10m long

  8. Chondrichthyes • Sharks and rays • Reduced calcification of bones is derived • Denser than water • Oil filled liver to reduce density • Suspension feeders or active predators

  9. Chondrichthyes • Rays • Bottoms dwellers • Predators • Enhanced pectoral fin

  10. Chondrichthyes • Sharks • Acute senses for predatory lifestyle • Detect electric fields • No eardrums, entire body receives sounds waves

  11. Osteichthyes • “bony fish” • Paraphyletic without tetrapods • For now, just the aquatic variety • Operculum covering gills • Swim bladder • Evolved from lungs • Scales

  12. Bony Fish: Ray Fins • Most of fish • Fins supported by bony rays • Evolved in freshwater and then moved to the sea • Some still make this transition during life

  13. Bony Fish: Lobe Fins • Pectoral and pelvis fins have rod shaped bone surrounded by muscle. • Used muscular fins to walk on land in swampy areas • Only three lineages remain

  14. Bony Fish: Lobe Fins • Coelacanths • Thought to be extinct until 1999 • Lungfishes • Only six species • Gills and lungs to gulp air • When ponds dry up, can estivate in the mud • Tetrapods (next section of notes)

  15. Tetrapods • Gnathostomes with 4 limbs

  16. Amphibians • Salamanders, frogs and caecilians • “double life” • But not in salamanders and caecilians • Damp habitats • Exchange gas across skin • External fertilization • Some carry fertilized eggs on back

  17. Amniotes • Tetrapods with a terrestrially adapted egg • Amniotic egg • Amnion- fluid filled cavity to protect against physical shock • Chorion- exchange gases • Yolk sac- stockpile of nutrients • Allantois- waste products • Covered in shell or remains in mother’s body • Rib cage to enhance breathing through lungs

  18. Reptiles: Traits • Scales containing keratin • Shelled eggs • Internal fertilization • Ectothermic • Derive body heat from surroundings • EXCEPT birds • Diapsids

  19. Reptile Diversity • Lepidosaurs • Tuataras • Squamates • Snakes • Lizards

  20. Reptiles: Turtles • Distinctive because of shield • Fused to the ribs and vertebrae • May be most closely related to crocodiles

  21. Alligators and Crocodiles • Appeared during Triassic • Some were as big as 12m long

  22. Reptiles: Birds • Most characters are derived for function in flying • Wings and feathers • Efficient lungs • Acute vision • Larger brain • Lighter bones

  23. Mammals • Amniotes that have hair and produce milk

  24. Mammals: Diversity • Monotremes • Australia and New Guinea • Platypus and echidnas • Lay eggs • Marsupials • Give birth to live young early in development • Offspring continue to develop in pouch • Eutherians • Offspring are born well developed

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