1. Animals with Backbones
Vertebrates
Animals with Backbones

2. Vertebrates
Animals in the sub-phylum Vertebrata have spinal cords and brains
Marine vertebrates include: sharks, fish, turtles, birds, seals and whales

3. Class Agnatha: The jawless fishes
Simple, more primitive fish that lack jaws. May represent the ancestors of bony fish and sharks.
i.e hagfish and lamprey
Characteristics include:
No jaws
Cartilaginous skeletons
Lack scales, paired fins
Long, eel-like
Two class divisions:
Myxini (hagfish)
Petromyzontida (lampreys)

4. Class Osteichthyes: The bony fishes
Osteichthyes contains the majority of the ocean’s fish
Characteristics include:
Jawed fish with skeletons made of bone
Operculum: bony skin flap outside gills that helps fish breathe when not swimming
Most use a swim bladder to keep them from sinking (adding or releasing gas)
Swim bladders allow fish to hover motionless in the ocean.
Most reproduce externally
Bony fish have lateral lines that detect water motion and vibrations. This is how schools of fish can coordinate

5. Anatomy of a bony, ray-finned fish
Fins are used for movement, support, and protection

11. Chondrichthyes: Cartilaginous fishes
Class Chondrichthyes means ‘cartilaginous fish’ and consists of sharks, rays, skates and close relatives
They share common features:
Jaws
Cartilage skeletons, not true bone
Fatty liver used for buoyancy
Lack swim bladder
Most have placoid scales (modified teeth and are covered with a hard enamel)