1. End Show Slide 1 of 50 Copyright Pearson Prentice Hall Biology

2. End Show Slide 2 of 50 Copyright Pearson Prentice Hall 32-1 Introduction to the Mammals

3. End Show 32-1 Introduction to the Mammals Slide 3 of 50 Copyright Pearson Prentice Hall Mammals What are the characteristics of mammals?

4. End Show 32-1 Introduction to the Mammals Slide 4 of 50 Copyright Pearson Prentice Hall Mammals All mammals have two notable features: hair and mammary glands. In females, mammary glands produce milk to nourish the young.

5. End Show 32-1 Introduction to the Mammals Slide 5 of 50 Copyright Pearson Prentice Hall Mammals In addition to having hair and the ability to nourish their young with milk, all mammals breathe air. have four-chambered hearts. are endotherms that generate their body heat internally.

6. End Show 32-1 Introduction to the Mammals Slide 6 of 50 Copyright Pearson Prentice Hall Evolution of Mammals When did mammals evolve?

7. End Show 32-1 Introduction to the Mammals Slide 7 of 50 Copyright Pearson Prentice Hall Evolution of Mammals Mammalian fossils are characterized by a lower jaw with a large, teeth-bearing bone connected directly to the skull by a joint, and distinctive features of the limbs and the backbone.

8. End Show 32-1 Introduction to the Mammals Slide 8 of 50 Copyright Pearson Prentice Hall Evolution of Mammals Mammals are descended from ancient reptiles. Ancestors of modern mammals diverged from ancient reptiles during the Carboniferous Period. For millions of years, various mammal-like reptiles lived alongside other reptile groups.

9. End Show 32-1 Introduction to the Mammals Slide 9 of 50 Copyright Pearson Prentice Hall Evolution of Mammals The first true mammals appeared during the late Triassic Period, about 220 million years ago. These mammals were very small and probably nocturnal.

10. End Show 32-1 Introduction to the Mammals Slide 10 of 50 Copyright Pearson Prentice Hall Evolution of Mammals After the extinction of dinosaurs, mammals underwent an adaptive radiation. They increased in size and occupied many new niches. The Cenozoic Era is called the Age of Mammals.

11. End Show 32-1 Introduction to the Mammals Slide 11 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals The mammalian body has adapted in varied ways to a great many habitats.

12. End Show 32-1 Introduction to the Mammals Slide 12 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals Body Temperature Control Mammals are endotherms. A high rate of metabolism helps mammals generate body heat. Mammals have external body hair that helps them keep warm. Subcutaneous fat, which is a layer of fat located beneath the skin, also helps conserve body heat.

13. End Show 32-1 Introduction to the Mammals Slide 13 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals Many mammals have sweat glands that help cool the body. If its body temperature gets too high, the mammal sweats. Evaporation of sweat then cools the body. Some mammals pant to cool down.

14. End Show 32-1 Introduction to the Mammals Slide 14 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals How do mammals maintain homeostasis?

15. End Show 32-1 Introduction to the Mammals Slide 15 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals The ability of mammals to regulate their body heat from within is an example of homeostasis.

16. End Show 32-1 Introduction to the Mammals Slide 16 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals Feeding Because of its high metabolic rate, a mammal must eat a lot of food to maintain homeostasis. Some mammals are herbivores. Some mammals are carnivores. Some mammals, including humans, are omnivores. Certain whales are filter feeders.

17. End Show 32-1 Introduction to the Mammals Slide 17 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals As mammals evolved, the form and function of their jaws and teeth became adapted to eat foods other than insects. The joint between the skull and lower jaw allowed mammals to evolve larger, more powerful jaw muscles and different ways of chewing.

18. End Show 32-1 Introduction to the Mammals Slide 18 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals Wolf Molars and premolars Horse Jaw joint Canines Incisors Herbivore Carnivore Jaws and Teeth of Mammals

19. End Show 32-1 Introduction to the Mammals Slide 19 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals Canines: Canines are pointed teeth. Carnivores use them for piercing, gripping, and tearing. In herbivores, they are reduced or absent. WolfHorse Canines

20. End Show 32-1 Introduction to the Mammals Slide 20 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals Incisors: Chisel-like incisors are used for cutting, gnawing, and grooming. WolfHorse Incisors

21. End Show 32-1 Introduction to the Mammals Slide 21 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals Molars crush and grind food. The ridged shape of the wolf’s molars and premolars allows them to interlock during chewing, like the blades of scissors. The broad, flattened molars and premolars of horses are adapted for grinding tough plants. Molars and premolars WolfHorse

22. End Show 32-1 Introduction to the Mammals Slide 22 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals A mammal’s digestive tract breaks down and absorbs the type of food that it eats. Carnivores have a short intestine because enzymes quickly digest meat. Herbivores have a longer intestine because tough, fibrous plant tissues take longer to digest.

23. End Show 32-1 Introduction to the Mammals Slide 23 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals Cows have a stomach chamber called the rumen, in which swallowed plant food is stored and processed. It contains bacteria that digest the cellulose of plant tissues.

24. End Show 32-1 Introduction to the Mammals Slide 24 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals Respiration All mammals use lungs to breathe. A diaphragm is a large, flat muscle at the bottom of a mammal’s chest cavity that helps in breathing.

25. End Show 32-1 Introduction to the Mammals Slide 25 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals When an animal inhales, chest muscles lift the rib cage up and out. The diaphragm pulls the chest cavity down. The combined actions of the chest muscles and diaphragm increase the volume of the chest cavity. The increase in volume pulls air into the lungs.

26. End Show 32-1 Introduction to the Mammals Slide 26 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals When an animal exhales, chest muscles lower the rib cage. The diaphragm relaxes, and the volume of the chest cavity decreases. Air is then pushed out of the lungs.

27. End Show 32-1 Introduction to the Mammals Slide 27 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals Circulation The mammalian circulatory system has two loops and a four-chambered heart. The right side of the heart receives oxygen-poor blood from the body and pumps it to the lungs. The left side receives oxygen-rich blood from the lungs and pumps it to the rest of the body.

28. End Show 32-1 Introduction to the Mammals Slide 28 of 50 Copyright Pearson Prentice Hall Mammalian heart Right atrium Right ventricle Left atrium Left ventricle Complete division Form and Function in Mammals

29. End Show 32-1 Introduction to the Mammals Slide 29 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals Excretion Kidneys extract nitrogenous wastes from the blood in the form of urea. Urea, other wastes, and water combine to form urine. From the kidneys, urine flows to a urinary bladder, where it is stored until it is eliminated.

30. End Show 32-1 Introduction to the Mammals Slide 30 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals The kidneys of mammals help maintain homeostasis by filtering urea from the blood, as well as by excreting excess water or retaining needed water.

31. End Show 32-1 Introduction to the Mammals Slide 31 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals The kidneys control the amount of water in the body. This enables mammals to live in many habitats in which they could not otherwise survive.

32. End Show 32-1 Introduction to the Mammals Slide 32 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals Response Mammals have well-developed brains with three main parts: cerebrum—controls thinking and learning cerebellum—controls muscular coordination medulla oblongata—regulates involuntary body functions

33. End Show 32-1 Introduction to the Mammals Slide 33 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals Mammalian Brain

34. End Show 32-1 Introduction to the Mammals Slide 34 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals The cerebrum has a well-developed outer layer called the cerebral cortex, which is the center of thinking and other complex behaviors. Some behaviors, such as reading, are possible only with the human cerebral cortex. Mammals other than humans also exhibit complex behaviors.

35. End Show 32-1 Introduction to the Mammals Slide 35 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals Mammals rely on highly developed senses to detect and respond to stimuli from their external environment. Many have well-developed senses of smell and hearing.

36. End Show 32-1 Introduction to the Mammals Slide 36 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals All mammalian ears have the same basic parts, but they differ in their ability to detect sound. Dogs, bats, and dolphins detect sounds at higher frequencies than humans can. Elephants detect sounds at much lower frequencies.

37. End Show 32-1 Introduction to the Mammals Slide 37 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals The ability to distinguish colors varies among species. Color vision is most useful to animals that are active during the day.

38. End Show 32-1 Introduction to the Mammals Slide 38 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals Chemical Controls Mammals have endocrine glands that regulate body activities by releasing hormones. Hormones are substances produced in one part of an organism that affect another part of the same organism. Hormones are carried by the blood to the organs that they affect.

39. End Show 32-1 Introduction to the Mammals Slide 39 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals Fighting Disease The immune system helps protect animals from disease. Barriers, such as the skin, prevent pathogens from entering the body. Specialized cells and chemicals recognize and destroy pathogens.

40. End Show 32-1 Introduction to the Mammals Slide 40 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals Movement Mammals have backbones that flex vertically and side to side. Shoulder and pelvic girdles are streamlined and flexible, permitting both front and hind limbs to move in many ways. Variations in limb bones and muscles permit a variety of movements.

41. End Show 32-1 Introduction to the Mammals Slide 41 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals Monkey Mole Seal Bat Horse The limbs and digits (fingers and toes) of many mammals are adapted to their particular way of life. Note the variety of lengths and shapes of the limb bones. Homologous bones are the same color in all the drawings.

42. End Show 32-1 Introduction to the Mammals Slide 42 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals Reproduction Mammals reproduce by internal fertilization. The male deposits sperm inside the reproductive tract of the female, where fertilization occurs. All newborn mammals feed on their mother’s milk.

43. End Show 32-1 Introduction to the Mammals Slide 43 of 50 Copyright Pearson Prentice Hall Young mammals need care from one or both parents when they are born and for a long time afterward. Parental care ensures that young will survive and reproduce. The duration and intensity of parental care varies among different species. Form and Function in Mammals

44. End Show 32-1 Introduction to the Mammals Slide 44 of 50 Copyright Pearson Prentice Hall Form and Function in Mammals Some mammal species, such as lions, live in groups in which the young may be cared for by adults other than the parents. Group living provides young mammals with complex social interaction among adults and juveniles.

45. End Show - or - Continue to: Click to Launch: Slide 45 of 50 Copyright Pearson Prentice Hall 32-1

46. End Show Slide 46 of 50 Copyright Pearson Prentice Hall 32-1 One characteristic commonly used to determine whether fossils are mammals is a.subcutaneous fat. b.mammary glands. c.a jaw joint that allows movement from side to side. d.hair or fur.

47. End Show Slide 47 of 50 Copyright Pearson Prentice Hall 32-1 How many chambers do mammalian hearts have? a.2 b.3 c.4 d.6

48. End Show Slide 48 of 50 Copyright Pearson Prentice Hall 32-1 Mammals are called endotherms because they a.produce milk to nourish their young. b.have well-developed sense organs. c.have powerful jaws and specialized teeth. d.generate their body heat internally.

49. End Show Slide 49 of 50 Copyright Pearson Prentice Hall 32-1 The first true mammals appeared in the fossil record a.soon after the extinction of the dinosaurs. b.about the same time as the first reptiles. c.during the Triassic when dinosaurs were the dominant land animals. d.long after the extinction of the dinosaurs.

50. End Show Slide 50 of 50 Copyright Pearson Prentice Hall 32-1 The duration of parental care in mammals a.varies among different species. b.is one to four weeks. c.is six months to a year. d.is intermediate compared to reptiles.

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