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# 19.3: Amphibians

Difficulty Level: At Grade Created by: CK-12

## Lesson 19.3: True or False

Name___________________ Class______________ Date________

Write true if the statement is true or false if the statement is false.

_____ 1. Amphibians live on land and in the water.

_____ 2. Amphibians are the first true vertebrates with four limbs.

_____ 3. Amphibians are ectothermic, meaning they can warm their body through metabolic processes.

_____ 4. Amphibians have a cloaca, a shared body cavity with separate openings for wastes and gametes.

_____ 5. Of all amphibians, frogs generally have the best vision and hearing, and a larynx to make sounds.

_____ 6. Most amphibians breathe with lungs as larvae and with gills as adults.

_____ 7. Just like their vertebrate relatives, the reptiles, birds, and mammals, amphibians produce amniotic eggs.

_____ 8. Many amphibians can absorb oxygen through their skin.

_____ 9. During metamorphosis, the amphibian grows legs, grows a tail, and develops lungs.

_____ 10. Frogs croak when searching for mates.

_____ 11. Salamanders cannot jump; instead, they walk and swim.

_____ 12. The amphibian tadpole resembles a fish.

_____ 13. Caecilians are most closely related to salamanders; these amphibians also walk and swim.

_____ 14. Amphibians have important roles in food webs, as predators of birds and snakes, and as prey for worms, snails, and insects.

_____ 15. The frog's back legs are modified for jumping, whereas the toad's back legs are modified for swimming.

Name___________________ Class______________ Date________

Read these passages from the text and answer the questions that follow.

Amphibian Reproduction and Development

Amphibians reproduce sexually with either external or internal fertilization. They attract mates in a variety of ways. For example, the loud croaking of frogs is their mating call. Each frog species has its own distinctive call that other members of the species recognize as their own. Most salamanders use their sense of smell to find a mate. The males produce a chemical odor that attracts females of the species.

Amphibian Eggs

Unlike other tetrapod vertebrates (reptiles, birds, and mammals), amphibians do not produce amniotic eggs. Therefore, they must lay their eggs in water so they won’t dry out. Their eggs are usually covered in a jelly-like substance. The “jelly” helps keep the eggs moist and offers some protection from predators.

Amphibians generally lay large numbers of eggs. Often, many adults lay eggs in the same place at the same time. This helps to ensure that eggs will be fertilized and at least some of the embryos will survive. Once eggs have been laid, most amphibians are done with their parenting.

Amphibian Larvae

The majority of amphibian species go through a larval stage that is very different from the adult form, as you can see from the frog in the diagram below. The early larval, or tadpole, stage resembles a fish. It lacks legs and has a long tail, which it uses to swim. The tadpole also has gills to absorb oxygen from water. As the larva undergoes metamorphosis, it grows legs, loses its tail, and develops lungs. These changes prepare it for life on land as an adult frog.

Frog Development: From Tadpole to Adult. A frog larva (tadpole) goes through many changes by adulthood. How do these changes prepare it for life as an adult frog? (Frog illustrations illustrated by Meyers Konversations-Lexikon, colored and arranged by TomCatX, and under the public domain.)

Questions

1. What are two ways amphibians attract mates?

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2. Where must amphibians lay their eggs? Why?

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3. Why do many amphibians lay their eggs together?

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## Lesson 19.3: Multiple Choice

Name___________________ Class______________ Date________

Circle the letter of the correct choice.

1. Amphibian skin
1. contains keratin, which in amphibians is not very tough, and it allows gases and water to pass through the skin.
2. is usually moist and has scales.
3. can be either moist or dry.
4. contains keratin, a tough, fibrous protein which keeps skin water- and air-tight.
2. Amphibians breathe
1. with lungs.
2. with lungs as larvae and with gills as adults.
3. with gills as larvae and with lungs as adults.
4. with gills.
3. Which statement is true of amphibian larvae?
1. The amphibian larval stage is very different from the adult form.
2. The early amphibian larvae resembles a fish.
3. The early amphibian larvae has gills to absorb oxygen from water.
4. all of the above
1. are separate orders of amphibian.
2. have front and back legs that are modified for jumping.
3. have back legs that are modified for jumping.
4. none of the above
5. Salamanders
1. have a long body with short legs.
2. are adapted for walking and swimming rather than jumping.
3. can regrow legs that have been lost to predators.
4. all of the above
6. Caecilians
1. have a long, worm-like body without legs.
2. are adapted for walking and swimming.
3. can regrow legs that have been lost to predators.
4. have front and back legs that are modified for jumping.
7. Which statement is true of amphibians and their role in the ecosystem?
1. Amphibians are important predators of animals such as birds, snakes, raccoons, and fish.
2. Amphibians are important in an ecosystem as both prey and predators.
3. As adults, amphibians are omnivores, feeding on both plants and animals.
4. all of the above
8. Amphibians evolved into
1. reptiles.
2. birds.
3. mammals.
4. fish.

## Lesson 19.3: Vocabulary I

Name___________________ Class______________ Date________

Match the vocabulary word with the proper definition.

Definitions

_____ 1. the only continent without amphibians

_____ 2. shared body cavity

_____ 3. a tough, fibrous protein found in the skin, scales, feathers, hair, and nails

_____ 4. vertebrates with four limbs

_____ 5. have back legs that are modified for jumping; spends more time in water then related species

_____ 6. have a long body with short legs

_____ 7. have a long, worm-like body without legs

_____ 8. have back legs that are modified for jumping; spends more time on land then related species

_____ 9. the early larval stage

_____ 10. the changing of larvae into the adult form

_____ 11. having a body temperature about the same as the environment.

_____ 12. vertebrates that divide their time between freshwater and terrestrial habitats

Terms

a. amphibian

b. Antarctica

c. caecilians

d. cloaca

e. ectothermic

f. frogs

g. keratin

h. metamorphosis

i. salamanders

k. tetrapod

## Lesson 19.3: Vocabulary II

Name___________________ Class______________ Date________

Fill in the blank with the appropriate term.

1. The loud croaking of frogs is their ____________ call.

2. Most amphibians breathe with ____________ as larvae and with lungs as adults.

3. Amphibians must lay their eggs in ____________.

4. ____________ spend more time in water, and ____________ spend more time on land.

5. The majority of amphibian species go through a ____________ stage that is very different from the adult form.

6. ____________ have the ability to regenerate legs that have been lost to predators.

7. The amphibian digestive, excretory, and reproductive systems share a body cavity called the ____________.

8. Amphibian skin contains ____________, a tough, fibrous protein.

9. Amphibians are the first true tetrapods, or vertebrates with ____________ limbs.

10. Amphibians divide their time between freshwater and terrestrial ____________.

11. Amphibians were the earliest land ____________.

12. Amphibians evolved about ____________ million years ago.

## Lesson 19.3: Critical Writing

Name___________________ Class______________ Date________

Thoroughly answer the question below. Use appropriate academic vocabulary and clear and complete sentences.

Identify and describe the three living amphibian orders.

Feb 23, 2012

Feb 20, 2015