Chordates Part 2

Transition from Jawless fishes to Jaws:

Class- Chondrichthyes (cartilaginous fishes):

Have skeleton made of cartilage Lighter and more flexible than bone Moveable jaws Well developed teeth Mouth is ventral Tail provides propulsion Pectoral and pelvic fins produce lift Buoyancy- oil in large liver Sink if not swimming Dermal denticles, scales like teeth, sandpaper skin Examples: Sharks, rays, skates 100 million years old (living fossils)

Class- Osteichthyes (Bony fish): 27,000 species, 98% of all fishes Skeleton made of bone

Thin flexible scales

Gill cover or operculum