1. Section Objectives:
Objective 1: Describe the evolutionary origin of modern mammals
Objective 2: Describe basic characteristics of modern mammals
Objective 3: Explain the characteristics and classification of Cetaceans
Objective 4: Explain the characteristics and classification of Chiropterans
Objective 5: Explain the characteristics and classification of Primates
Objective 6: Explain the characteristics and classification of Ungulates
Objective 7: Explain the characteristics and classification of Carnivores
Objective 8: Explain the characteristics and classification of Monotremes and Marsupials

2. Section 32.1 Summary – pages 841 – 847
What is a mammal?
Mammals, like birds, are endotherms.
Section 32.1 Summary – pages 841 – 847

3. Section 32.1 Summary – pages 841 - 847
What is a mammal?
They have hair and produce milk to nurse their young.
Mammals also have diaphragms, four-chambered hearts, specialized teeth, modified limbs, and highly developed brains.
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4. Section 32.1 Summary – pages 841 - 847
Mammals have hair
Like feathers, mammalian hair, made out of the protein keratin, is also thought to have evolved from scales.
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5. Section 32.1 Summary – pages 841 - 847
Mammals have hair
The arrangement of hair provides insulation and waterproofing and thereby conserves body heat.
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6. Section 32.1 Summary – pages 841 - 847
Mammals have hair
Mammals also have internal feedback mechanisms that signal the body to cool off when it gets too warm.
Mammals cool off by panting and through the action of sweat glands.
Panting releases water from the nose and mouth, which results in a loss of body heat.
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7. Section 32.1 Summary – pages 841 - 847
Mammals have hair
Sweat glands help regulate body temperature by secreting moisture onto the surface of the skin.
As the moisture evaporates, it transfers heat from the body to the surrounding air.
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8. Section 32.1 Summary – pages 841 - 847
Mammals nurse their young
Mammals have several types of glands, which are a group of cells that secrete fluids.
They include glands that produce saliva, sweat, oil, digestive enzymes, hormones, milk, and scent.
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9. Section 32.1 Summary – pages 841 - 847
Mammals nurse their young
Mammals also feed their young from mammary glands, possibly modified sweat glands, which produce and secrete milk, a liquid that is rich in fats, sugars, proteins, minerals, and vitamins.
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10. Section 32.1 Summary – pages 841 - 847
Mammals nurse their young
Mammals nurse their young until they are able to digest and absorb nutrients from solid foods.
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11. Section 32.1 Summary – pages 841 – 847
Respiration and circulation in mammals
The mammals’ diaphragm helps expand the chest cavity to aid the flow of oxygen into their lungs.
Position of ribs when exhaling
Position of ribs when inhaling
Lungs when exhaling
Lungs when inhaling
Position of diaphragm when inhaling
Position of diaphragm when exhaling
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12. Section 32.1 Summary – pages 841 - 847
Respiration and circulation in mammals
A diaphragm is the sheet of muscle located beneath the lungs that separates the chest cavity from the abdominal cavity, where other organs are located.
Position of diaphragm when inhaling
Position of diaphragm when exhaling
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13. Section 32.1 Summary – pages 841 - 847
Respiration and circulation in mammals
Mammals have four-chambered hearts in which oxygenated blood is kept entirely separate from deoxygenated blood.
Left atrium
Right atrium
Right ventricle
Left ventricle
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14. Section 32.1 Summary – pages 841 - 847
Respiration and circulation in mammals
Circulation also removes waste products from cells and helps regulate body temperature.
Blood helps keep a constant cellular environment, which maintains homeostasis.
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15. Section 32.1 Summary – pages 841 - 847
Most mammals have specialized teeth
Mammals with teeth have different kinds that are adapted to the type of food the animal eats.
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16. Section 32.1 Summary – pages 841 - 847
Most mammals have specialized teeth
The pointed incisors of moles grasp and hold small prey.
The chisel-like incisors of beavers are modified for gnawing.
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17. Section 32.1 Summary – pages 841 - 847
Most mammals have specialized teeth
A lion’s canines puncture and tear the flesh of its prey.
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18. Section 32.1 Summary – pages 841 - 847
Most mammals have specialized teeth
Premolars and molars are used for slicing or shearing, crushing, and grinding.
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19. Section 32.1 Summary – pages 841 - 847
Most mammals have specialized teeth
Many hoofed mammals have an adaptation called cud chewing that enables the cellulose in plant cell walls to be broken down into nutrients they can absorb and use.
When plant material is swallowed, it moves into the first two of four pouches in the stomach where cellulose in the cell walls is broken down by bacteria.
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20. Section 32.1 Summary – pages 841 - 847
Most mammals have specialized teeth
The partially digested food, called cud, is repeatedly brought back up into the mouth.
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Most mammals have specialized teeth
After more chewing, the cud is swallowed again and when the food particles are small enough they are passed to the other stomach areas, where digestion continues.
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Mammals have modified limbs
Mammal limbs are adapted for a variety of methods of food gathering.
Primates, for example, use their opposable thumb to grasp objects—including fruits and other foods.
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Mammals can learn
Mammals can accomplish complex behaviors, such as learning and remembering what they have learned.
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Mammals can learn
Primates, including humans, are perhaps the most intelligent animals.
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Mammals can learn
Chimpanzees, for example, can use tools, work machines, and use sign language to communicate with humans.
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26. Section 32.1 Summary – pages 841 - 847
Mammals can learn
Cerebrum
Motor area
Sensory area
Speech area
Language area
Vision area
Taste area
General interpretation area
Intellect, learning, and personality
Balance area
Hearing area
Brain stem
Cerebellum
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27. Section 32.1 Summary – pages 841 - 847
A Mammal
Heart
Diaphragm
Glands
Teeth
Mammary glands
Hair
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