Vertebrates b Phylum: Chordata b Subphylum: Vertebrata

Characteristics b Notochord b Dorsal Hollow Nerve Cord b Pharyngeal Pouches b Post-Anal Tail

b Bones/Cartilage b Cranium b Endoskeleton

Vertebrate Evolution b 550 million years ago b Jawless Fishes

Fishes b Class Agnatha Hagfishes & LampreysHagfishes & Lampreys

b Cartilage Skeletons, External Fertilization, and Freshwater Fertilization.

b Class Chondrichthyes Sharks, Rays, and SkatesSharks, Rays, and Skates

b Placoid Scales, Lateral Line System, Olfactory Bulbs, Cartilage Skeletons, Internal Fertilization

b Class Osteichthyes Bony Fishes (lobe-finned and ray-finned)Bony Fishes (lobe-finned and ray-finned)

b Bone, Lungs or swim bladder, Scales, Gills, & Mostly External Fertilization.

Amphibians

Amphibian Characteristics b b Aquatic larval stage to a terrestrial adult form: metamorphosis. b b Moist, thin skin with no scales. b b Feet, if present, lack claws and often are webbed.

b b Gills, lungs, and skin used in respiration. b b Eggs lack shells. b b External Fertilization b b 3 Chambered Heart

Reptiles Reptiles evolved from Amphibians.

Amniotic Egg

Water-Tight Skin

Gas Exchange b Lungs

Energy b Ectotherms

Circulation

b Crocodiles have a 4 chambered heart.

Birds

Feathers b Down, Contour, & Flight

Skeleton b Lightweight and Rigid

Endothermic Metabolism b Eat often to supply energy to maintain their warmth.

Respiratory System

Mammals

Characteristics b Endothermy b Hair b 4 Chambered Heart b Milk b Single Jawbone b Specialized Teeth