1. Section 2 Characteristics of Mammals
Chapter 43 Mammals
Section 2
Characteristics of Mammals

2. Endothermy
Allows mammals to live in cold environments and remain active
Provides energy for strenuous activities like migrating
Fast metabolism requires more energy
Cold environments- blubber & thick furred animals

4. Circulatory System Two atria and two ventricles
Septum- wall of tissue separates ventricles
No mixing of deoxygenated and oxygenated blood
Complete septum- adaptation that allows mammals’ bodies to transport oxygen more efficiently

6. Respiratory System Efficient gas exchange
Large lungs- many alveoli- small sacs where gas exchange occurs
Expand ribcage and take in air through lungs
Diaphragm- contraction enlarges thorax and increases thoracic activity- breathing

8. Feeding & Digestion Incisors- cut food Canines- grip, puncture, & tear
Premolars- shear, shred, cut, or grind
Molars- grind, crush, or cut
Baleen whales- baleen- thin plates of keratin- trap prey

10. Digesting Plants Cellulose- polymer of sugar glucose- hard to digest
Stomach- four chambers
One chamber = true stomach
Rumen- another chamber- contains symbiotic microorganisms

11. Digesting Plants
Partly digested in rumen, then regurgitated, chewed again and swallowed again
Animals may regurgitate multiple times
Ruminant animals- cows, sheep, goats, giraffes, deer

12. Digesting Plants Horses, zebras, rodents, rabbits, & elephants- cecum
Cecum- large sac that branches from small intestines and ferments food
Animals with a cecum do not chew cud

15. Nervous System Mammal brain is large Cerebrum- outer region of brain
Sense organs, movements, behavior, memory, learning
Vision, hearing, smell, touch, taste
Echolocation- emit high-frequency sound-waves, which bounce off objects

17. Development
Mammals develop differently

18. Monotremes Lay one to two eggs Incubate by body heat
Yolk nourishes young
Once young hatch, female feeds young milk until fully developed

20. Marsupials Develop in uterus for short time
When only 2-3 cm, young develop in mother’s pouch and attach to a nipple to feed
Young stay in pouch for several months

22. Placental Mammals Well-developed young are born live
Placenta provides nourishment & oxygen
After birth, infants feed on milk for several weeks or months

24. REVIEW!!!
A mammal eats about ten times as much food as a lizard of the same size. Explain this difference.
Describe the function of a rumen.