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2. Standardized Test Prep
Resources
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Visual Concepts
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Standardized Test Prep

3. Chapter 40 Table of Contents
Amphibians
Table of Contents
Section 1 Origin and Evolution of Amphibians
Section 2 Characteristics of Amphibians
Section 3 Reproduction in Amphibians

4. Section 1 Origin and Evolution of Amphibians
Chapter 40
Objectives
Describe the three preadaptations involved in the transition from aquatic to terrestrial life.
Describe two similarities between amphibians and lobe-finned fishes.
List five characteristics of living amphibians.
Name the three orders of living amphibians, and give an example of each.

5. Chapter 40 Adaptation to Land
Section 1 Origin and Evolution of Amphibians
Chapter 40
Adaptation to Land
Preadaptations - are adaptations in an ancestral group that allow a shift to new functions which are later favored by natural selection.
Lobe-finned fishes had several preadaptations that allowed them to transition to life on land.
bone structure
pouches in digestive tracts for gas exchange
nostrils
higher metabolism
efficient hearts

6. Chapter 40 From Fin to Limb
Section 1 Origin and Evolution of Amphibians
Chapter 40
From Fin to Limb

7. Adaptation to Land, continued
Section 1 Origin and Evolution of Amphibians
Chapter 40
Adaptation to Land, continued
Characteristics of Early Amphibians
Amphibians and lobe-finned fishes share many anatomical similarities, including:
similar skull
similar vertebral column
similar bone structure in fins and limbs
early amphibians had a large tail fin and lateral line canals

8. Characteristics of Early Amphibians
Section 1 Origin and Evolution of Amphibians
Chapter 40
Characteristics of Early Amphibians

9. Adaptation to Land, continued
Section 1 Origin and Evolution of Amphibians
Chapter 40
Adaptation to Land, continued
Diversification of Amphibians
About 300 million years ago amphibians split into two main evolutionary lines.
One line included ancestors of reptiles, the other line included the ancestors of modern amphibians.

10. Adaptation to Land, continued
Section 1 Origin and Evolution of Amphibians
Chapter 40
Adaptation to Land, continued
Diversification of Amphibians
Today there are about 4,500 species of amphibians belonging to three orders:
Anura - includes frogs and toads
Caudata - includes salamanders and newts
Gymnophiona - includes caecilians (legless tropical amphibians)

11. Chapter 40 Modern Amphibians
Section 1 Origin and Evolution of Amphibians
Chapter 40
Modern Amphibians
Modern amphibians share several key characteristics
Most change from an aquatic larval stage to a terrestrial adult form, in a transformation called metamorphosis.
Most have moist, thin skin with no scales.
Feet, if present, lack claws and often are webbed.
Most use gills, lungs, and skin in respiration.
Eggs lack multicellular membranes or shells, are usually laid in water, and are usually fertilized externally.

12. Characteristics of Amphibians
Section 1 Origin and Evolution of Amphibians
Chapter 40
Characteristics of Amphibians

13. Modern Amphibians, continued
Section 1 Origin and Evolution of Amphibians
Chapter 40
Modern Amphibians, continued
Order Anura
Order includes frogs and toads.
Members may be fully aquatic, fully terrestrial, or amphibious.
Most reproduce in water, laying eggs that hatch into swimming larvae called tadpoles.
Larvae are herbivores. Adults are carnivorous and will eat any animal they can capture.

14. Modern Amphibians, continued
Section 1 Origin and Evolution of Amphibians
Chapter 40
Modern Amphibians, continued
Order Caudata
Includes salamanders (may also be called newts).
Members may be fully aquatic, fully terrestrial, or amphibious.
Many reproduce in water. Some reproduce on land, with no swimming larval stage.
Larvae and adults are carnivorous.
Some have no lungs, and respire through their skin only.

15. Modern Amphibians, continued
Section 1 Origin and Evolution of Amphibians
Chapter 40
Modern Amphibians, continued
Order Gymnophiona
Includes caecilians (legless amphibians that resemble small snakes).
Most are burrowing. They have small eyes beneath skin or bone, and are often blind.
All are carnivorous.
All are thought to have internal fertilization.
Some lay eggs which the female guards, others develop inside the female.

16. Phylogenetic Diagram of Amphibians
Section 1 Origin and Evolution of Amphibians
Chapter 40
Phylogenetic Diagram of Amphibians

17. Chapter 40 Types of Amphibians
Section 1 Origin and Evolution of Amphibians
Chapter 40
Types of Amphibians

18. Chapter 40 Objectives Section 2 Characteristics of Amphibians
Relate the structure of amphibian skin to the types of habitats in which amphibians can survive.
Identify three adaptations for life on land shown by the skeleton of a frog.
Sequence the flow of blood through an amphibian’s heart.
Describe how a frog fills its lungs with air.
Describe the digestive and excretory systems of amphibians.
Discuss an amphibian’s nervous system.

19. Chapter 40 Skin Amphibian skin serves two important functions:
Section 2 Characteristics of Amphibians
Chapter 40
Skin
Amphibian skin serves two important functions:
Respiration - The skin is permeable to gases and water. Mucous glands secrete a lubricant that keeps the skin moist in air.
Protection - The skin protects amphibians from infection and secretes a foul-tasting or poisonous mucus that protects amphibians from predators.

20. External Structure of a Frog
Section 2 Characteristics of Amphibians
Chapter 40
External Structure of a Frog

21. Section 2 Characteristics of Amphibians
Chapter 40
Skeleton
A strong skeleton supports the body of amphibians against the force of gravity.
Vertebrae interlock to form a strong, rigid structure.
Strong limbs assist with standing and walking.
Pectoral and pelvic girdles transfer weight to the limbs.
Skeletons of frogs are specialized for jumping and landing.

22. Chapter 40 Skeleton, continued Section 2 Characteristics of Amphibians
Fused bones add strength to the forelimbs and hind limbs.
Thick arm bones and pectoral girdle absorb shock of landing.
Long hind legs allow frogs to jump farther.
Lengthened pelvic girdle and fused vertebrae add support.

23. Chapter 40 Circulatory System
Section 2 Characteristics of Amphibians
Chapter 40
Circulatory System
The circulatory system is divided into two loops.
Pulmonary circulation - carries deoxygenated blood from the heart to the lungs and back to the heart.
Systemic circulation - carries oxygenated blood from the heart to the body and back to the heart.

24. Circulatory System, continued
Section 2 Characteristics of Amphibians
Chapter 40
Circulatory System, continued
Three chambered heart:

25. Amphibian Heart Structure
Section 2 Characteristics of Amphibians
Chapter 40
Amphibian Heart Structure

26. Frog Heart and Double-Loop Circulation
Section 2 Characteristics of Amphibians
Chapter 40
Frog Heart and Double-Loop Circulation

27. Chapter 40 Respiration Amphibians use two forms of respiration
Section 2 Characteristics of Amphibians
Chapter 40
Respiration
Amphibians use two forms of respiration
Pulmonary respiration - respiration through the lungs
Cutaneous respiration - respiration through the skin

28. Respiration, continued
Section 2 Characteristics of Amphibians
Chapter 40
Respiration, continued
Amphibians use positive pressure breathing, shown below.

29. Amphibian Lung Structure
Section 2 Characteristics of Amphibians
Chapter 40
Amphibian Lung Structure

30. Respiration in Amphibians
Section 2 Characteristics of Amphibians
Chapter 40
Respiration in Amphibians

31. Chapter 40 Digestive System Section 2 Characteristics of Amphibians
Includes the pharynx, esophagus, stomach, liver, gallbladder, small intestine, large intestine, and cloaca.
The upper part of the small intestine is called the duodenum.
The coiled middle portion of the small intestine is the ileum.
A membrane that holds the small intestine in place is called the mesentery.
Waste materials are stored in the cloaca and exit the body through the vent.

32. Digestive System, continued
Section 2 Characteristics of Amphibians
Chapter 40
Digestive System, continued
Accessory Glands
The liver produces bile, which is stored in the gallbladder and helps break down fat.
The pancreas secretes enzymes that help break down food into particles that can be absorbed by the blood.

33. Internal Structure of a Frog
Section 2 Characteristics of Amphibians
Chapter 40
Internal Structure of a Frog

34. Chapter 40 Excretory System
Section 2 Characteristics of Amphibians
Chapter 40
Excretory System
The kidneys are the primary excretory organ, and filter nitrogenous wastes from the blood.
Wastes combined with water are known as urine.
Urine flows from the kidneys to the cloaca and then to the urinary bladder, which branches off the cloaca.
Nitrogenous wastes are converted from ammonia to urea, which is highly concentrated and helps conserve water.

35. Chapter 40 Nervous System Section 2 Characteristics of Amphibians
The olfactory lobes are larger in amphibians than in fish.
The cerebrum is responsible for behavior and learning.
The optic lobes process information from the eyes.
The cerebellum is responsible for muscular coordination.
The medulla oblongata controls heart rate and respiration rate.

36. Chapter 40 Nervous System Sense Organs -
Section 2 Characteristics of Amphibians
Chapter 40
Nervous System
Sense Organs -
Larvae have a lateral line, most adults do not.
The eyes are covered by a nictitating membrane, a transparent moveable membrane that protects the eye.
Sound is detected by the inner ear.
Sounds are transmitted to the inner ear by the tympanic membrane, or eardrum, and the columella, a small bone that extends between the tympanic membrane and the inner ear.

37. Section 2 Characteristics of Amphibians
Chapter 40
Anatomy of a Frog

38. Anatomy of a Frog (part 2)
Section 2 Characteristics of Amphibians
Chapter 40
Anatomy of a Frog (part 2)

39. Section 3 Reproduction in Amphibians
Chapter 40
Objectives
Explain how a male frog attracts a female of the same species.
Discuss the reproductive system of a frog.
Describe the life cycle of a frog.
Describe the changes that occur during metamorphosis in frogs.
Identify two examples of parental care in amphibians.

40. Courtship and Fertilization
Section 3 Reproduction in Amphibians
Chapter 40
Courtship and Fertilization
Males attract females with a mating call.
Females only respond to males of the same species.
The male clings to the female in an embrace called amplexus.
Eggs and sperm are released into the water.
Fertilization is external.

41. Courtship and Fertilization, continued
Section 3 Reproduction in Amphibians
Chapter 40
Courtship and Fertilization, continued
Reproductive system
Male - includes two bean-shaped testes located near the kidneys that produce sperm during the breeding season.
Female - includes a pair of large ovaries containing thousands of tiny immature eggs. During the breeding season the eggs mature.

42. Chapter 40 Life Cycle When the eggs hatch, a tadpole is released.
Section 3 Reproduction in Amphibians
Chapter 40
Life Cycle
When the eggs hatch, a tadpole is released.
The tadpole grows and slowly changes from an aquatic larva into an adult in a process called metamorphosis.
Metamorphosis is controlled by a hormone called thyroxine.
Some amphibians do not produce thyroxine and remain in the larval stage their entire life.
Some amphibians do not have a larval stage and hatch from the egg as small versions of the adult.

43. Section 3 Reproduction in Amphibians
Chapter 40
Life Cycle of a Frog

44. Section 3 Reproduction in Amphibians
Chapter 40
Amphibian Life Cycle

45. Section 3 Reproduction in Amphibians
Chapter 40
Parental Care
Parental care increases the likelihood that the offspring will survive.
Some species guard their eggs until they hatch.
Some species sit on their eggs to prevent them from drying out.
The male Darwin’s frog carries the eggs in his vocal sacs until the larvae finish metamorphosis.
Female gastric brooding frogs swallow their eggs and the larvae mature in the stomach.

46. Chapter 40 Multiple Choice
Standardized Test Prep
Multiple Choice
1. The forelimbs of vertebrates evolved from which structures in lobe-finned fishes?
A. anal fin
B. pelvic fin
C. pectoral fins
D. pectoral girdle

47. Chapter 40 Multiple Choice
Standardized Test Prep
Multiple Choice
1. The forelimbs of vertebrates evolved from which structures in lobe-finned fishes?
A. anal fin
B. pelvic fin
C. pectoral fins
D. pectoral girdle

48. Multiple Choice, continued
Chapter 40
Standardized Test Prep
Multiple Choice, continued
2. Amphibians must lay eggs in water primarily for what reason?
F. The eggs are not laid in nests.
G. The eggs need oxygen from water.
H. The eggs need protection from predators.
J. The eggs do not have multicellular membranes and a shell.

49. Multiple Choice, continued
Chapter 40
Standardized Test Prep
Multiple Choice, continued
2. Amphibians must lay eggs in water primarily for what reason?
F. The eggs are not laid in nests.
G. The eggs need oxygen from water.
H. The eggs need protection from predators.
J. The eggs do not have multicellular membranes and a shell.

50. Chapter 40 Multiple Choice
Standardized Test Prep
Multiple Choice
3. Metamorphosis must take place before amphibians are able to do what?
A. swim
B. live on land
C. respire with gills
D. feed themselves

51. Chapter 40 Multiple Choice
Standardized Test Prep
Multiple Choice
3. Metamorphosis must take place before amphibians are able to do what?
A. swim
B. live on land
C. respire with gills
D. feed themselves

52. Multiple Choice, continued
Chapter 40
Standardized Test Prep
Multiple Choice, continued
The figure below shows a longitudinal section, ventral view, of a frog heart. Use the figure below to answer question 4.

53. Multiple Choice, continued
Chapter 40
Standardized Test Prep
Multiple Choice, continued
4. Identify the source of blood flow in the section of the heart labeled 1.
F. the body
G. the aorta
H. the lungs
J. both lungs and body

54. Multiple Choice, continued
Chapter 40
Standardized Test Prep
Multiple Choice, continued
4. Identify the source of blood flow in the section of the heart labeled 1.
F. the body
G. the aorta
H. the lungs
J. both lungs and body

55. Chapter 40 Multiple Choice 5. Anura : frogs :: Gymnophiona : A. toads
Standardized Test Prep
Multiple Choice
5. Anura : frogs :: Gymnophiona :
A. toads
B. newts
C. caecilians
D. salamanders

56. Chapter 40 Multiple Choice 5. Anura : frogs :: Gymnophiona : A. toads
Standardized Test Prep
Multiple Choice
5. Anura : frogs :: Gymnophiona :
A. toads
B. newts
C. caecilians
D. salamanders

57. Multiple Choice, continued
Chapter 40
Standardized Test Prep
Multiple Choice, continued
The figure below shows an artist’s rendering of Ichthyostega. Use the figure to answer the question that follows.

58. Multiple Choice, continued
Chapter 40
Standardized Test Prep
Multiple Choice, continued
6. Ichthyostega is an early amphibian. Which of the following characteristics is most likely to help it live on land?
F. fishlike tail
G. seven-toed feet
H. four strong limbs
J. lateral-line canals on the head

59. Multiple Choice, continued
Chapter 40
Standardized Test Prep
Multiple Choice, continued
6. Ichthyostega is an early amphibian. Which of the following characteristics is most likely to help it live on land?
F. fishlike tail
G. seven-toed feet
H. four strong limbs
J. lateral-line canals on the head

60. Chapter 40 Short Response
Standardized Test Prep
Short Response
Modern amphibians are a diverse group, but they do have some common characteristics.
Describe five key characteristics shared by modern amphibians.

61. Short Response, continued
Chapter 40
Standardized Test Prep
Short Response, continued
Modern amphibians are a diverse group, but they do have some common characteristics.
Describe five key characteristics shared by modern amphibians.
Answer: Metamorphosis from larva to adult; moist, thin skin; clawless feet; respiration with lungs, skin, and gills; shell-less eggs

62. Chapter 40 Extended Response
Standardized Test Prep
Extended Response
Base your answers to parts A & B on the information below.
Frogs breathe by a positive pressure system.
Part A Describe how frogs move air into their lungs. Which part of inhaling is “positive pressure?”
Part B Describe how frogs move air out of their lungs and into the atmosphere.

63. Extended Response, continued
Chapter 40
Standardized Test Prep
Extended Response, continued
Answer:
Part A The mouth floor drops, sucking air in. The nostrils seal and the mouth floor lifts (positive pressure), which forces air into the lungs.
Part B: The body wall muscles and lung elasticity force lung air into the mouth, which makes the floor drop. The floor then lifts to force air out of nostrils.