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Animal diversity – the chordates

Animal diversity – the chordates. Chapter 26. Chordate Characteristics. Notochord Dorsal, hollow nerve cord Gill slits Tail. Modern Chordate Groups. Invertebrate Chordates. Lancelets are the only group of chordates that retains all chordate characteristics as adults.

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Animal diversity – the chordates

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  1. Animal diversity – the chordates Chapter 26

  2. Chordate Characteristics • Notochord • Dorsal, hollow nerve cord • Gill slits • Tail

  3. Modern Chordate Groups

  4. Invertebrate Chordates • Lancelets are the only group of chordates that retains all chordate characteristics as adults.

  5. Invertebrate Chordates • Tunicates have typical chordate larvae, but adults retain only the pharynx with gill slits

  6. Craniates • Craniates have a braincase of cartilage or bone (cranium) that encases the brain, paired eyes, and other sensory structures on the head • Craniates includes fishes, amphibians, reptiles, birds, and mammals • Hagfishes are the only modern craniates that are not vertebrates

  7. Hagfishes (Class Myxini) Is that a hagfish purse or an eel-skin purse? • Soft bodied, boneless fishes Squidoo. 2011. http://www.squidoo.com/eelskin-wallets Squidoo. 2011. http://www.squidoo.com/eelskin-wallets

  8. Chordate Family Tree

  9. Vertebrate Traits and Trends • Endoskeleton • Vertebral column • Jaws • Paired fins or appendages • Gills or lungs • Closed circulatory system • Other organ systems

  10. Vertebrates have backbones • Embryonic notochord eventually replaced by a vertebral column • Vertebral column composed of bone or cartilage • Vertebral column functions • Possess living internal skeleton that has allowed great size and mobility

  11. The Major Vertebrate Groups • Jawless fishes • Jawed fishes • Amphibians • Reptiles and birds • Mammals

  12. Jawless fishes • Earliest vertebrates lacked jaws • Early vertebrates were jawless fishes (extinct) whose bodies were protected by bony armor plates

  13. Jawless fishes • Lampreys (Class Petromyzontidae) • Represents distinct early branch of chordate evolutionary tree • Has large round sucker that surrounds mouth • Single nostril on top of head • Nerve cord of lampreys protected by segments of cartilage • May be parasitic or nonparasitic • Parasitic-have rasping teeth on tongue which it uses to grasp host • Will burrow through body wall in order to feast on blood and body fluids

  14. Lampreys Freshwater lamprey - nonparasitic Sea lamprey - parasitic

  15. Jawed fishes • Have Jaws! – important adaptation • Earliest jawed organisms were fish • Benefits of jaws • Allow to grasp, tear, or crush food • Could exploit more food sources • Gave rise to the cartilaginous fishes, ray-finned fishes, lobe-finned fishes

  16. Early Jawed Fishes - Placoderms BHC. 2009. http://facweb.bhc.edu/academics/science/harwoodr/geol102/Study/Images/Placoderm.jpg UC Berkeley. 2011. http://www.ucmp.berkeley.edu/vertebrates/basalfish/placodermi.html

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