1. Chapter 35 Table of Contents Section 1 The Mammalian Body
Mammals
Table of Contents
Section 1 The Mammalian Body
Section 2 Today’s Mammals

2. Chapter 35 Objectives Describe three functions of hair.
Section 1 The Mammalian Body
Objectives
Describe three functions of hair.
Relate a mammal’s teeth to its diet.
Summarize how mammals maintain a high body temperature.
Relate the characteristics of mammals to one mammal, the grizzly bear.
Describe parental care in mammals.

3. Key Characteristics of Mammals
Chapter 35
Section 1 The Mammalian Body
Key Characteristics of Mammals
Almost all of today’s large, land-dwelling vertebrates are mammals.
Mammals are well-adapted for terrestrial living. They are able to retain water more efficiently than reptiles.

4. Characteristics of Mammals
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Characteristics of Mammals

5. Key Characteristics of Mammals, continued
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Hair
Of all animal species, only mammals have hair. A hair is a filament composed mainly of dead cells filled with the protein keratin.
The primary function of hair is insulation. The hair of some mammals helps them blend in with their surroundings. In some mammals, specialized hairs serve a sensory function.

6. Chapter 35 Mammalian Teeth
Section 1 The Mammalian Body
Mammalian Teeth
Mammals have only two sets of teeth throughout their lives: baby teeth or milk teeth, then permanent teeth.
Mammals have four kinds of teeth: incisors, canines, premolars, and molars.
A mammal’s teeth are specialized for the food it eats.

7. Chapter 35 Body Temperature
Section 1 The Mammalian Body
Body Temperature
Like birds, mammals are endotherms. They can be active at any time of day or night. They can also live in cold climates.
A mammal must eat about 10 times as much food as an ectotherm of similar size. Mammals have a high metabolic rate and require considerable amounts of oxygen.

8. Body Temperature, continued
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Body Temperature, continued
Respiratory System
Mammalian lungs are more efficient at obtaining oxygen than are reptilian and amphibian lungs.
Mammalian lungs contain alveoli, small chambers that provide a very large surface area.

9. Chapter 35
Section 1 The Mammalian Body
Mammalian Lungs

10. Body Temperature, continued
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Body Temperature, continued
Heart and Circulatory System
Mammals have a four-chambered heart. A septum completely divides the ventricle into two pumping chambers.
One chamber pumps oxygen-rich blood to the body. The other chamber pumps oxygen-poor blood to the lungs. The two kinds of blood do not mix.

11. External Structures of a Grizzly Bear
Chapter 35
Section 1 The Mammalian Body
External Structures of a Grizzly Bear

12. Internal Structures of a Grizzly Bear
Chapter 35
Section 1 The Mammalian Body
Internal Structures of a Grizzly Bear

13. Chapter 35
Section 1 The Mammalian Body
Parental Care
Mammals nourish their young with milk. Milk is produced by mammary glands located on the female’s chest or abdomen.
Young mammals are nourished on milk from birth until weaning, the time when the mother stops nursing them.

14. Chapter 35
Section 2 Today’s Mammals
Objectives
Recognize how mammals are adapted to different environments.
Compare reproductive patterns in monotremes, marsupials, and placental mammals.
Relate the distribution of monotremes and marsupials to the breakup of Pangaea.

15. Chapter 35 Mammalian Diversity
Section 2 Today’s Mammals
Mammalian Diversity
Mammals are more diverse in size, anatomy, and habitat than all other vertebrate groups.

16. Comparison of Bats and Whales
Chapter 35
Section 2 Today’s Mammals
Comparison of Bats and Whales

17. Chapter 35
Section 2 Today’s Mammals
Reproduction
All mammals reproduce by internal fertilization.
Mammals are divided into three groups based on differences in how and where the fertilized egg develops.

18. Reproduction, continued
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Monotremes
The monotremes (order Monotremata) are the most primitive of all mammals. Among living mammals, only monotremes reproduce by laying eggs.
There are three living monotreme species: the duckbill platypus and two species of echidnas.

19. Reproduction, continued
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Reproduction, continued
Marsupials
The marsupials (order Marsupialia) include kangaroos, koalas, and opossums.
In marsupial mammals, the young are born incompletely developed. They crawl to their mother’s nipples located in a pouch on her abdomen, then continue their development for several months.

20. Reproduction, continued
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Reproduction, continued
Placental Mammals
The young of placental mammals develop within the female’s uterus. The placenta enables the diffusion of nutrients and oxygen from the mother to the fetus. The period of time between fertilization and birth is called the gestation period.
Most domestic animals (such horses, cattle, dogs, and cats) are placental mammals.

21. Modern Placental Mammals
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Section 2 Today’s Mammals
Modern Placental Mammals
There are 19 orders of placental mammals, which include more than 90 percent of all mammal species.
The vast majority of mammal species are found within 12 orders.

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Order 1: Order Rodentia
About 40 percent of all mammal species are rodents. Rodents have teeth that are specialized for gnawing.
Most rodents are small in size. Rodents have a rapid rate of reproduction.

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Order 2: Order Chiroptera
This order is composed of bats, the only mammals capable of true flight. Most bats live in groups and are active only at night.
Most bats eat insects, using echolocation to catch insects while in flight.

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Order 3: Order Insectivora
This order consists of small mammals, such as the shrew, that eat mainly insects.
Insectivores are the mammals most similar to the ancestors of the placental mammals.

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Order 4: Order Carnivora
Most species in this order are flesh-eating hunters.
Carnivores consist of two subgroups: the cat family and the dog family.
Carnivores have excellent senses of smell, vision, and hearing.

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Order 5: Order Pinnipedia
This order of marine carnivores includes seals and sea lions.
All four limbs of pinnipeds are modified as flippers for swimming. Their bodies are streamlined for rapid movement through the water.

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Order 6: Order Primates
Humans belong to the order Primates.
Other members of this order include the prosimians, monkeys, and apes.
Most nonhuman primates are tree-dwellers.

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Order 7: Order Artiodactyla
Mammals belonging to this order and the following order, Perissodactyla, are ungulates, mammals with hooves. Artiodactyls have an even number of toes.
Many artiodactyls have a stomach with a storage chamber called a rumen. Mammals with a rumen regurgitate partially digested food, called cud, rechew it, and swallow it again for further digestion.

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Order 8: Order Perissodactyla
Ungulates with an odd number of toes within their hooves are classified as perissodactyls. This order includes horses, zebras, and rhinoceroses.
Perissodactyls lack a rumen and do not chew their cud.

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Order 9: Order Cetacea
Cetaceans are divided into two groups: the predatory toothed whales, dolphins, and porpoises, and the filter-feeding baleen whales.

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Order 10: Order Lagomorpha
This order is composed of rabbits and hares. Like rodents, lagomorphs have long, continually growing incisors. They also have another pair of incisors that grow behind the first pair.
Rabbits and hares have long hind legs and are specialized for hopping.

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Order 11: Order Sirenia
Sirenians include dugongs and manatees, barrel-shaped marine animals that eat aquatic plants. They have front limbs modified as flippers.
Sirenians are closely related to elephants and are often called sea cows.

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Order 12: Order Proboscidea
There are two living species in this order, the African elephant and the Indian elephant. These animals are the largest land animals alive today.
An elephant’s upper incisor teeth are modified into long ivory tusks.

34. Chapter 35 Multiple Choice
Standardized Test Prep
Multiple Choice
Use the drawing below and your knowledge of science to answer questions 1–3.

35. Multiple Choice, continued
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Standardized Test Prep
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1. Which organisms in structure C contribute to the digestion of plant material?
A. algae
B. yeasts
C. bacteria
D. tunicates

36. Multiple Choice, continued
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Standardized Test Prep
Multiple Choice, continued
1. Which organisms in structure C contribute to the digestion of plant material?
A. algae
B. yeasts
C. bacteria
D. tunicates

37. Multiple Choice, continued
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Standardized Test Prep
Multiple Choice, continued
2. Which statement describes the function of structure A?
F. Fertilized eggs are implanted here.
G. Air is drawn into structure A.
H. Milk is produced here.
J. Nutrients and oxygen diffuse to a fetus through structure A.

38. Multiple Choice, continued
Chapter 35
Standardized Test Prep
Multiple Choice, continued
2. Which statement describes the function of structure A?
F. Fertilized eggs are implanted here.
G. Air is drawn into structure A.
H. Milk is produced here.
J. Nutrients and oxygen diffuse to a fetus through structure A.

39. Multiple Choice, continued
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Standardized Test Prep
Multiple Choice, continued
3. Which statement describes the structure B?
A. Two pumping chambers supply oxygen-rich blood to the lungs.
B. Two pumping chambers supply oxygen-poor blood to the lungs.
C. One pumping chamber supplies blood to the lungs and body organs.
D. One pumping chamber supplies oxygen-poor blood to the lungs, and one pumping chamber supplies oxygen-rich blood to the body organs.

40. Multiple Choice, continued
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Standardized Test Prep
Multiple Choice, continued
3. Which statement describes the structure B?
A. Two pumping chambers supply oxygen-rich blood to the lungs.
B. Two pumping chambers supply oxygen-poor blood to the lungs.
C. One pumping chamber supplies blood to the lungs and body organs.
D. One pumping chamber supplies oxygen-poor blood to the lungs, and one pumping chamber supplies oxygen-rich blood to the body organs.