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 temperatureEndotherms – high metabolism generates body heat; allows for:

activity at any time of day or nightmammals to live in more habitats than reptiles or amphibians

sustained activity such as running or flying

Respiratory systemAlveoli air sacs which provide a large internal surface area which provides for exchange of O2 and CO2

Heart & circulatory systemDouble-loop circulation4 chambered heart with completely divided septum

No mixing of high O2 and low O2 blood

Parental careMammary glands – modified sweat glands which produce milk for young

Rich in protein, carbohydrates (lactose), fat, water, minerals and immunity

Weaning – mother stops nursing youngYoung mammals spend a long time with mothers compared to other animals, even after weaning