• Skin with hair or fur
• females have mammary glands that secrete milk
• constant body temperature

• skin with feathers
• eggs with hard shell
• beak for feeding
• constant body temperature

Reptiles

Snake, Lizard, Tortoise, Crocodile

• skin with scales
• membranous or leathery-shelled eggs laid on land
• lungs for breathing
• changing body temperature

Amphibia

Frog, Toad, Salamander

• egss without a shell, usually laid in water
• soft, moist skin without scales
• larvae usually live in water and have gills
• adults usually live on land and have lungs
• Changing body temperature