3. Table of Contents – pages iv-v Unit 1: What is Biology? Unit 2: Ecology Unit 3: The Life of a Cell Unit 4: Genetics Unit 5: Change Through Time Unit 6: Viruses, Bacteria, Protists, and Fungi Unit 7: Plants Unit 8: Invertebrates Unit 9: VertebratesVertebrates Unit 10: The Human Body

4. Table of Contents – pages iv-v Unit 1: What is Biology? Chapter 1: Biology: The Study of Life Unit 2: Ecology Chapter 2: Principles of Ecology Chapter 3: Communities and Biomes Chapter 4: Population Biology Chapter 5: Biological Diversity and Conservation Unit 3: The Life of a Cell Chapter 6: The Chemistry of Life Chapter 7: A View of the Cell Chapter 8: Cellular Transport and the Cell Cycle Chapter 9: Energy in a Cell

5. Table of Contents – pages iv-v Unit 4: Genetics Chapter 10: Mendel and Meiosis Chapter 11: DNA and Genes Chapter 12: Patterns of Heredity and Human Genetics Chapter 13: Genetic Technology Unit 5: Change Through Time Chapter 14: The History of Life Chapter 15: The Theory of Evolution Chapter 16: Primate Evolution Chapter 17: Organizing Life’s Diversity

6. Table of Contents – pages iv-v Unit 6: Viruses, Bacteria, Protists, and Fungi Chapter 18: Viruses and Bacteria Chapter 19: Protists Chapter 20: Fungi Unit 7: Plants Chapter 21: What Is a Plant? Chapter 22: The Diversity of Plants Chapter 23: Plant Structure and Function Chapter 24: Reproduction in Plants

7. Table of Contents – pages iv-v Unit 8: Invertebrates Chapter 25: What Is an Animal? Chapter 26: Sponges, Cnidarians, Flatworms, and Roundworms Chapter 27: Mollusks and Segmented Worms Chapter 28: Arthropods Chapter 29: Echinoderms and Invertebrate Chordates

8. Table of Contents – pages iv-v Unit 9: VertebratesVertebrates Chapter 30: Fishes and Amphibians Chapter 31: Reptiles and Birds Chapter 32: MammalsMammals Chapter 33: Animal Behavior Unit 10: The Human Body Chapter 34: Protection, Support, and Locomotion Chapter 35: The Digestive and Endocrine Systems Chapter 36: The Nervous System Chapter 37: Respiration, Circulation, and Excretion Chapter 38: Reproduction and Development Chapter 39: Immunity from Disease

9. Unit Overview – pages 840 - 841 Vertebrates Fishes and Amphibians Reptiles and Birds Mammals Animal Behavior

10. Chapter Contents – page xii Chapter 32 MammalsMammals 32.1: Mammal CharacteristicsMammal Characteristics 32.1: Section CheckSection Check 32.2: Diversity of MammalsDiversity of Mammals 32.2: Section CheckSection Check Chapter 32 SummarySummary Chapter 32 AssessmentAssessment

11. Chapter Intro-page 840 What You’ll Learn You will identify the characteristics of mammals. You will compare and contrast three groups of living mammals and examine their relationships to their ancient ancestors.

12. 32.1 Section Objectives – page 841 Distinguish mammalian characteristics. Section Objectives: Explain how the characteristics of mammals enable them to adapt to most habitats on Earth.

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

14. Section 32.1 Summary – pages 841 - 847 They have hair and produce milk to nurse their young. What is a mammal? Mammals also have diaphragms, four- chambered hearts, specialized teeth, modified limbs, and highly developed brains.

15. Section 32.1 Summary – pages 841 - 847 Like feathers, mammalian hair, made out of the protein keratin, is also thought to have evolved from scales. Mammals have hair

16. Section 32.1 Summary – pages 841 - 847 Mammals have hair The arrangement of hair provides insulation and waterproofing and thereby conserves body heat.

17. 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.

18. 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.

19. 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.

20. 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.

21. 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.

22. 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 diaphragm when exhaling Position of diaphragm when inhaling Position of ribs when exhaling Lungs when exhaling Position of ribs when inhaling Lungs when inhaling

23. 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. Section 32.1 Summary – pages 841 - 847 Position of diaphragm when exhaling Position of diaphragm when inhaling Respiration and circulation in mammals

24. Section 32.1 Summary – pages 841 - 847 Mammals have four-chambered hearts in which oxygenated blood is kept entirely separate from deoxygenated blood. Right atrium Right ventricle Left atrium Left ventricle Respiration and circulation in mammals

25. Section 32.1 Summary – pages 841 - 847 Circulation also removes waste products from cells and helps regulate body temperature. Blood helps keep a constant cellular environment, which maintains homeostasis. Respiration and circulation in mammals

26. Section 32.1 Summary – pages 841 - 847 Mammals with teeth have different kinds that are adapted to the type of food the animal eats. Most mammals have specialized teeth

27. Section 32.1 Summary – pages 841 - 847 The pointed incisors of moles grasp and hold small prey. The chisel-like incisors of beavers are modified for gnawing. Most mammals have specialized teeth

28. Section 32.1 Summary – pages 841 - 847 A lion’s canines puncture and tear the flesh of its prey. Most mammals have specialized teeth

29. Section 32.1 Summary – pages 841 - 847 Most mammals have specialized teeth Premolars and molars are used for slicing or shearing, crushing, and grinding.

30. Section 32.1 Summary – pages 841 - 847 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. Most mammals have specialized teeth

31. Section 32.1 Summary – pages 841 - 847 The partially digested food, called cud, is repeatedly brought back up into the mouth. Most mammals have specialized teeth

32. Section 32.1 Summary – pages 841 - 847 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. Most mammals have specialized teeth

33. Section 32.1 Summary – pages 841 - 847 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.

34. Section 32.1 Summary – pages 841 - 847 Mammals can learn Mammals can accomplish complex behaviors, such as learning and remembering what they have learned.

35. Section 32.1 Summary – pages 841 - 847 Mammals can learn Primates, including humans, are perhaps the most intelligent animals.

36. Section 32.1 Summary – pages 841 - 847 Mammals can learn Chimpanzees, for example, can use tools, work machines, and use sign language to communicate with humans.

37. Section 32.1 Summary – pages 841 - 847 Motor area Sensory area Language area Vision area General interpretation area Cerebrum Speech area Taste area Intellect, learning, and personality Hearing area Brain stem Cerebellum Balance area Mammals can learn

38. Section 32.1 Summary – pages 841 - 847 A Mammal Glands Diaphragm Heart Teeth Mammary glands Hair

39. Section 1 Check Question 1 What two characteristics do mammals have that no other animal has? (TX Obj 2; 8C) Answer All mammals have hair and produce milk to nurse their young.

40. Section 1 Check What do scientists believe mammalian hair evolved from? (TX Obj 2; 8C) D. keratin C. skin B. scales A. feathers Question 2

41. Section 1 Check The answer is B. Like feathers, hair also is made out of keratin which leads scientists to believe that hair evolved from scales.

42. Section 1 Check How do a mammal’s teeth help it obtain food? (TX Obj 2; 8C) Question 3

43. Section 1 Check Mammals have teeth that are adapted to the type of food they eat. Canine teeth puncture and tear the flesh of prey. Premolars and molars are used for slicing, shearing, and crushing while incisors are used for gnawing and grasping.

44. Section 1 Check Which of the following helps a mammal take in large amounts of oxygen? (TX Obj 2; 8C, 10A) D. diaphragm C. teeth B. heart A. glands Question 4

45. Section 1 Check The answer is D, diaphragm. Glands Diaphragm Heart Teeth Mammary glands Hair

46. 32.2 Section Objectives – page 848 Distinguish among the three groups of living mammals. Section Objectives: Compare reproduction in egg-laying, pouched, and placental mammals.

47. Section 32.2 Summary – pages 848 - 851 Mammal Classification Scientists place mammals into one of three subclasses based on their method of reproduction.

48. Section 32.2 Summary – pages 848 - 851 Placental mammals: A great success Placental mammals give birth to young that have developed inside the mother’s uterus until their body systems are fully functional and they can live independently of their mother’s body.

49. Section 32.2 Summary – pages 848 - 851 Placental mammals: A great success The uterus is a hollow, muscular organ in which offspring develop. Nourishment of the young inside the uterus occurs through an organ called the placenta which develops during pregnancy.

50. Section 32.2 Summary – pages 848 - 851 Placental mammals: A great success The time during which placental mammals develop inside the uterus is called gestation. Development inside the mother’s body ensures that the offspring are protected from predators and the environment during the early stages of development.

51. Section 32.2 Summary – pages 848 - 851 Pouched mammals: The marsupials A marsupial is a mammal in which the young have a short period of development within the mother’s body, followed by a period of development inside a pouch made of skin and hair on the outside of the mother’s body.

52. Section 32.2 Summary – pages 848 - 851 Pouched mammals: The marsupials Most marsupials are found in Australia and surrounding islands. Scientists have found fossil marsupials on the continents that once made up Gondwana. These fossils support the idea that marsupials originated in South America, moved across Antarctica, and populated Australia before Gondwana broke up.

53. Section 32.2 Summary – pages 848 - 851 Monotremes: The egg layers The duck-billed platypus is a monotreme, a mammal that reproduces by laying eggs. Spiny anteaters, also called echidnas, belong to this subclass as well.

54. Section 32.2 Summary – pages 848 - 851 Monotremes: The egg layers Monotremes are found only in Australia, Tasmania, and New Guinea. Only three species of monotremes are alive today.

55. Section 32.2 Summary – pages 848 - 851 Monotremes: The egg layers The platypus, a mostly aquatic animal, has a broad, flat tail, much like that of a beaver. Its rubbery snout resembles the bill of a duck.

56. Section 32.2 Summary – pages 848 - 851 Monotremes: The egg layers The platypus has webbed front feet for swimming through water, but it also has sharp claws on its front and hind feet for digging and burrowing into the soil. Much of its body is covered with thick, brown fur.

57. Section 32.2 Summary – pages 848 - 851 The spiny anteater has course, brown hair, and its back and sides are covered with sharp spines that it can erect for defensive purposes when threatened by enemies. Monotremes: The egg layers

58. Section 32.2 Summary – pages 848 - 851 The first placental mammals appeared in the fossils record about 125 million years ago. Scientists trace the origins of placental mammals from a group of mouse-sized animals to a group of reptilian ancestors called therapsids. Origins of Mammals

59. Section 32.2 Summary – pages 848 - 851 Origins of Mammals Therapsids had features of both reptiles and mammals. They existed between 270 and 180 million years ago.

60. Section 32.2 Summary – pages 848 - 851 The mass extinction of the dinosaurs at the end of the Mesozoic Era, along with the breaking apart of Pangaea and changes in climate, opened up new niches for early mammals to fill. The Cenozoic Era is sometimes called the golden age of mammals because of the dramatic increase in their numbers and diversity. Origins of Mammals

61. Section 32.2 Summary – pages 848 - 851 Origins of Mammals Carnivores 270 species Artiodactyls 220 species Cetaceans 79 species Rodents 2000 species Chiropterans 925 species Proboscids 2 species Insectivores 375 species Primates 230 species Perissodactyls 270 species Marsupials 280 species Monotremes 3 species Placental mammals 4400 species Therapsids mammal-like reptiles Reptiles Amphibians Fishes Invertebrates Species numbers are approximate and subject to change pending discoveries or extinctions.

62. Section 2 Check Which of the following is NOT an example of a placental mammal? (TX Obj 2; 8C) Question 1 D. fox C. dog B. human A. kangaroo

63. Section 2 Check The answer is A. A kangaroo is a marsupial.

64. Section 2 Check What three events allowed mammals to fill new niches? (TX Obj 3; 7B) Question 2 Answer The mass extinction of the Mesozoic Era, the break up of Pangaea, and changes in climate opened up new niches for early mammals to fill.

65. Section 2 Check What is the difference between a monotreme and a marsupial? (TX Obj 2; 8C, 10A) Question 3

66. Section 2 Check Monotremes reproduce by laying eggs. A marsupial’s young begins development within the body but complete its development outside the body in a pouch made of skin and hair.

67. Chapter Summary – 32.1 Mammals are endotherms giving them the ability to maintain a fairly constant body temperature. Mammal Characteristics Hair is present on all mammals at some point in their lives. Mammals feed their young from modified sweat glands called mammary glands.

68. Chapter Summary – 32.1 Mammals with teeth have different kinds of teeth that are adapted to the type of food they eat. Mammal Characteristics Highly developed brains enable mammals to learn.

69. Chapter Summary – 32.2 Mammals are classified into three subclasses—placentals, marsupials, and monotremes—based on how they reproduce. Diversity of Mammals Placental mammals carry young inside the uterus until their body systems are fully functional. Nourishment inside the uterus occurs through an organ called the placenta.

70. Chapter Summary – 32.2 Marsupials carry partially developed young in a pouch on the outside of the mother’s body. Diversity of Mammals Monotremes are egg-laying mammals found only in Australia, Tasmania, and New Guinea.

71. Chapter Assessment Question 1 How many groups are mammals classified into? (TX Obj 2; 8C) D. four C. three B. two A. one

72. The answer is C. Mammals are classified as placental, marsupial, or as monotremes. Chapter Assessment

73. Question 2 Of the teeth shown, which set would most likely be used by an animal that feeds on grass? (TX Obj 2; 8C) D. C. B. A.

74. The answer is A. This skull contains primarily molars and premolars which are used to crush and grind food. Chapter Assessment

75. Question 3 What role do zoos play in the preservation of endangered species? Answer Zoos use captive breeding programs to increase populations of animals, educate the public, conduct research, and provide professional training for staff.

76. Chapter Assessment Question 4 Which organ in this mammal is responsible for keeping oxygenated and deoxygenated blood separate? (TX Obj 2; 8C, 10A)

77. Chapter Assessment The heart enables mammals to keep oxygenated and deoxygenated blood separate. This helps them maintain their high metabolism. Heart

78. Chapter Assessment Question 5 Which of the following is one way that mammals cool off? (TX Obj 2; 8C) D. by hibernating C. by panting B. by shedding A. by swimming

79. The answer is C. Mammals cool off by panting and through the action of sweat glands. Chapter Assessment

80. Question 6 Why are mammals considered to be one of the most successful groups of organisms? (TX Obj 2; 8C)

81. Chapter Assessment Mammals are capable of accomplishing complex behaviors such as learning and remembering what they have learned. Mammals also guard their young and teach them the skills they need to survive on their own.

82. Chapter Assessment Question 7 While walking through the forest, you find an animal skull. You notice that the teeth in the skull are primarily pointed and long. What can you infer about the diet of the animal? (TX Obj 2; 8C)

83. Chapter Assessment The animal was most likely a carnivore. Long, pointed incisors and canines are used to stab and tear flesh.

84. Photo Credits Digital Stock PhotoDisc Bill Tarpenning/USDA Digital Vision Alton Biggs

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