Vertebrates b Phylum Chordata b Subphylum Vertebrata Characteristics

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 & Lampreys

b. Cartilage Skeletons, External Fertilization, and Freshwater Fertilization.

b. Class Chondrichthyes • Sharks, 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)

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

Amphibians

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

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

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