1. Table of Contents Chapter Preview 12.1 What Is a Vertebrate?
12.2 Fishes
12.3 Amphibians
12.4 Reptiles
12.5 Birds
12.6 Mammals
12.1 Structure and Function of Vertebrates
12.2 Fishes
12.3 Amphibians
12.4 Reptiles
12.5 Birds
12.6 Mammals

2. Chapter Preview Questions
1. A group of similar cells that perform a specific function is called a(n)
a. organ.
b. tissue.
c. organ system.
d. organism.

3. Chapter Preview Questions
1. A group of similar cells that perform a specific function is called a(n)
a. organ.
b. tissue.
c. organ system.
d. organism.

4. Chapter Preview Questions
2. The major cause of extinction of species is
a. a change in the environment.
b. new diseases.
c. over-killing by predators.
d. competition with other species.

5. Chapter Preview Questions
2. The major cause of extinction of species is
a. a change in the environment.
b. new diseases.
c. over-killing by predators.
d. competition with other species.

6. Chapter Preview Questions
3. The term for the extinction of many organisms at the same time is
a. Permian extinction.
b. Pangaea.
c. Cambrian explosion.
d. mass extinction.

7. Chapter Preview Questions
3. The term for the extinction of many organisms at the same time is
a. Permian extinction.
b. Pangaea.
c. Cambrian explosion.
d. mass extinction.

8. Chapter Preview Questions
4. Most animals reproduce
a. sexually only.
b. asexually only.
c. with alternating sexual and asexual stages.
d. by binary fission.

9. Chapter Preview Questions
4. Most animals reproduce
a. sexually only.
b. asexually only.
c. with alternating sexual and asexual stages.
d. by binary fission.

10. How does the structure of vertebrates help them to function?
Two friends are looking at fishes in an aquarium. One friend refers to the fishes as animals. The other friend argues that
fishes aren’t animals because they don’t have four legs. Which friend is correct? Explain your answer.

11. Greek Word Origins amphibios
Meaning of Greek Word
Key Term
amphibian An animal that spends part of its life cycle on land and part in water
amphibios
living a double life

12. Greek Word Origins chordé
Meaning of Greek Word
Key Term
chordate An animal that has a flexible rod that supports the animalís back
chordé
string, cord

13. Greek Word Origins therme
Meaning of Greek Word
Key Term
endotherm An animal that produces enough heat within its body to control its body temperature
therme
heat

14. Apply It!
1. How does the meaning of amphibian relate to the Greek word from
which it comes?
An animal that lives for part of its life on land and part in water is living
a double life.
2. Can you think of an English word besides chordate that might
come from the Greek word chordé?
Sample: cord
3. In the list of key terms on the next page, find another term
besides endotherm that might come from the Greek word
therme. Then look up the meaning of the key term and check
how its meaning relates to the meaning of endotherm.
An ectotherm is an animal whose body does not produce much internal
heat. An endotherm, in contrast, is an animal whose body does produce
internal heat to maintain its temperature.

15. End of Chapter Preview

16. Section 1: What Is a Vertebrate?
What are the characteristics of chordates and vertebrates?
How have scientists been able to infer the relationships of major groups of vertebrates?
How do vertebrates differ in the way they control body temperature?

17. Ancient Jawless Fish
Look backward in time, into an ocean 530 million years ago. There you see a strange-looking creature—a jawless fish—that is about as long as your index finger.

18. Characteristics of Chordates
This lancelet shows the characteristics of a chordate: a notochord, a nerve cord down its back, and gill slits.

19. Evolution of Vertebrates
The pattern of vertebrate evolution is branching.

20. Click the SciLinks button for links on vertebrates.

21. Click the Video button to watch a movie about vertebrates.

22. End of Section: What Is a Vertebrate?

23. Section 2: Fishes
What are the characteristics of chordates and vertebrates?
How have scientists been able to infer the relationships of major groups of vertebrates?
How do vertebrates differ in the way they control body temperature?

24. Characteristics of Fishes
Most fishes obtain oxygen through gills. Water flows into the mouth of the fish and then over its gills. Oxygen moves into the blood and is delivered to the cells of the fish.

25. Bony Fishes
A bony fish has jaws, scales, a pocket on each side of the head that holds the gills, and a skeleton made of hard bones.

26. End of Section: Fishes

27. Section 3: Amphibians What is the life cycle of an amphibian?
How are adult amphibians adapted to living on land?

28. What Is an Amphibian?
During its metamorphosis from tadpole to adult, a frog’s body changes dramatically.

29. Living on Land
Many adult amphibians have lungs, a heart with three chambers, and a double-loop circulatory system.

30. Respiration and Circulation Activity
Click the Active Art button to open a browser window and access Active Art about respiration and circulation.

31. More on The Frog Life Cycle
Click the PHSchool.com button for an activity about the frog life cycle.

32. End of Section: Amphibians

33. Section 4: Reptiles What adaptations allow reptiles to live on land?
What are the characteristics of each of the three main groups of reptiles?
What environmental change may have caused the extinction of the dinosaurs?

34. Adaptations for Life on Land
The membranes and shell of an amniotic egg protect the developing embryo.

35. The Sex Ratio of Newly Hatched Alligators
The temperature of the developing eggs of the American alligator affects the sex ratio of the young. (Sex ratio is the number of females compared with the number of males.)

36. The Sex Ratio of Newly Hatched Alligators
Reading Graphs:
At which temperature(s) did only females hatch?
29.4ºC

37. The Sex Ratio of Newly Hatched Alligators
Drawing Conclusions:
What effect does the temperature of developing eggs have on the sex of the baby alligators?
The warmer the incubation temperature, the greater the proportion of males.

38. The Sex Ratio of Newly Hatched Alligators
Calculating:
If 100 eggs developed at 31.7ºC, about how many of the young would be male?
According to the graph, out of the 50 alligators that were incubated at 31.7ºC, about 40 (or 80%) were males. So 80% of 100 eggs (80) could be expected to hatch as males.

39. Extinct Reptiles–The Dinosaurs
Climate change may have caused the extinction of dinosaurs and other organisms.

40. Click the PHSchool.com button for an activity about reptiles.
More on Reptiles
Click the PHSchool.com button for an activity about reptiles.

41. Click the Video button to watch a movie about interpreting fossils.

42. End of Section: Reptiles

43. Section 5: Birds
What are the main characteristics of birds?

44. Characteristics of Birds
The bodies of most birds have adaptations for flight.

45. Characteristics of Birds
Air sacs and a four-chambered heart help birds obtain oxygen and move it to their cells.

46. Characteristics of Birds
Birds have four-chambered hearts and double-loop circulatory systems that efficiently move oxygen to their cells.

47. Respiration and Circulation Activity
Click the Active Art button to open a browser window and access Active Art about respiration and circulation.

48. Characteristics of Birds
Some birds like this hawk have a crop and a gizzard. The crop stores food, and the gizzard crushes food.

49. End of Section: Birds

50. Section 6: Mammals What characteristics do all mammals share?
What are the main groups of mammals and how do they differ in their reproduction?

51. Diversity of Mammals
The three main groups of mammals are monotremes, marsupials, and placental mammals.
kangaroo spiny anteater giraffe

52. Mammal Diversity
This circle graph shows the percentage of species of some types of mammals.

53. Mammal Diversity Reading Graphs: What percentage of species are bats?
21.8 %

54. Mammal Diversity Calculating: What percentage of species are not bats?
78.2 %

55. Mammal Diversity Graphing:
Suppose you used the data shown in the circle graph to make a bar graph. Which bar would be tallest?
The group with the greatest number of species, rodents, would be the tallest.

56. Mammal Diversity Predicting:
What total should all the percentages in the pie chart add up to? Do you have to add the percentages to obtain your answer? Explain
100; no, you do not have to add them because it is a circle chart—the entire chart stands for 100 percent of the items counted— in this case, mammal species.

57. Click the SciLinks button for links on mammals.

58. End of Section: Mammals

59. QuickTake Quiz
Click to start quiz.