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Jawless fish. Living species include lampreys and hagfish.

Class Agnatha. Jawless fish. Living species include lampreys and hagfish. Ostracoderms – armor plates of bony tissue Placoderms – mineral hardened backbone and jaw Significant because they may represent the ancestor of bony fish/sharks. Bone tissue with a vertebrae

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Jawless fish. Living species include lampreys and hagfish.

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  1. Class Agnatha • Jawless fish. • Living species include lampreys and hagfish. • Ostracoderms – armor plates of bony tissue • Placoderms – mineral hardened backbone and jaw • Significant because they may represent the ancestor of bony fish/sharks.

  2. Bone tissue with a vertebrae • part of inner skeleton, paired with muscle segments • Jaws started trend towards more complex sensory organs and nervous systems • Paired fins Key Innovations Bony Fish

  3. Key Innovations Bony Fish • Gills – large surface area for water to diffuse into blood vessels • Don't function out of water • Lungs – supplemented and then replaced gills • Increase effiency

  4. Characteristics of Cartilaginous Fish • Class Chondrichthyesincludes sharks, rays and their close relatives. • jawed fish, that lack a swim bladder, and cartilaginous skeletons. • 5-7 gill silts, stream lined body • “conveyor belt” of teeth. • Modified scales

  5. Sharks and Rays • Sharks and rays have other interesting characteristics: • lateral lines – lines of sensory hair along the length of the body, detect water motion and vibrations. • electroreception – the ability to sense minute electricity created by muscles and nerves. • ampullae of Lorenzini - visible pits near their snouts used to detect the electrical current. 5 - 6

  6. Ray-finned fish – flexible fin with support from skin and scales • Bony endoskeleton • Swim bladder – exchanges gases with blood to help with floatation (gulp air) Osteichthyes

  7. Characteristics of Bony Fish • Characteristics for life on the reef and for life in the open ocean: • lateral lines that detect water motion and vibrations. • open ocean fish have a torpedo-likestreamlined shape to minimizes drag and turbulence. 5 - 8

  8. Coelacanths only surviving group • Ventral fin are extensions of body with skeletal support Lobe-Finned

  9. Lungfish • Have gills and 1-2 small outpouching of gut wall • Sacs help take in O2 and remove CO2 • Must surface and gulp air (will drown if held under water) • Ancestor to tetrapod??

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