2. 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.

3. Key Innovations Bony Fish
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

4. 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

5. Characteristics of Cartilaginous Fish
Class Chondrichthyes includes 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

6. 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

7. Osteichthyes
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)

8. 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-like streamlined shape to minimizes drag and turbulence.
5 - 8

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

11. 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??