Chapter 25:Vertebrate Diversity

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

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

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

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

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