1. Chapter 25:Vertebrate Diversity

2. Section One: Vertebrate Orgins
Chordata
Made up of vertebrates, tunicates, and lancelets
Characteristics
Notochord: flexible skeletal support rod embedded in the animal’s back
Hollow nerve cord
Pharyngeal slits
Tail

3. Section One: Vertebrate Origins
Vertebrate Features and Classes
Endoskeleton
Classes
Agnatha: jawless fish
Chondrichthyes: cartilaginous fish (sharks)
Osteichthyes: bony fish
Amphibia
Reptilia
Aves: birds
Mammalia

4. Section Two: Fish Diversity
Gills: large sheets of tissue filled with capillaries that take oxygen from the water and release carbon dioxide
Countercurrent flow: the opposite flow of water against the blood in the fish gills
Cartilaginous fish are fish with a cartilage skeleton instead of a skeleton made of bone

5. Section Four: Amphibians
The first tetrapods (vertebrate with 4 limbs)
Breathe through their skin with gills or lungs
Return to water for reproduction
Salamander, frogs, and caecilians

6. Section Five: Vertebrates on Land
Amniotes
Vertebrate whose embryo is enclosed in an amniotic sac
Amniotic Egg: almost completely waterproof container that keeps the embryo from drying out as it develops
Placenta: membranous organ that develops in female mammals during pregnancy
Reptiles and Mammals
Keratin: protein that is water repellent found in the skin