1. Mammals Have hair Ability to nourish their young with milk Breathe air 4-chambered heart Endotherms

2. Environment Live in a wide variety of ecosystems Land, water, and flying mammals Food Source Must eat 10 times as much food as a reptile to maintain body heat Use jaws and teeth to eat (Specialized teeth) Digestive tract absorbs nutrients for the body to use

3. Maintaining Homeostasis - Internal (Circulation, Respiration, Excretion) lungs to breathe Have a diaphragm- powerful muscle 2 separate loops in circulatory system and a 4- chamber heart Kidneys help maintain homeostasis by filtering urea from the blood as well as by excreting excess water or retaining needed water Maintaining Homeostasis - External (Response) Highest developed brain Cerebral cortex- center of thinking and other complex behaviors Highly developed senses to detect and respond to stimuli from their external environment

4. Movement Backbone that flexes both vertically and side to side. Very flexible Move in a variety of ways depending on their lifestyle Reproduction Internal fertilization Feed on mother’s milk Most care for their young Duration of care varies among species Evolutionary Milestone Endotherm, Hair, mammary glands, breathe air, 3 middle-ear bones

5. Picture and Vocabulary Picture on page 827, Fig 32-7 – homologous structures Vocabulary: mammary gland (821), cerebral cortex (825)