Section 35.1

 Hair – all mammals have hair, even whales (a few whiskers on snout)  Filament composed of dead cells filled with keratin  Functions: insulation, camouflage, warning, sensory, defense

 Teeth – usually only 2 sets: milk teeth and permanent teeth  Functions: killing, chewing, protection, tools  Types : incisors – biting & cutting; canines – stabbing & holding, premolars and molars – crushing & chewing  Specialization – teeth are designed for the food the mammal eats

 Body temperature  Endotherms – high metabolism generates body heat; allows for:  activity at any time of day or night  mammals to live in more habitats than reptiles or amphibians  sustained activity such as running or flying

 Respiratory system  Alveoli air sacs which provide a large internal surface area which provides for exchange of O 2 and CO 2  Heart & circulatory system  Double-loop circulation  4 chambered heart with completely divided septum  No mixing of high O 2 and low O 2 blood

 Parental care  Mammary glands – modified sweat glands which produce milk for young  Rich in protein, carbohydrates (lactose), fat, water, minerals and immunity  Weaning – mother stops nursing young  Young mammals spend a long time with mothers compared to other animals, even after weaning