Download Amphibians: Amazing Animal

Amphibians:
Amazing Animal
1 videocassette....................23 minutes
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Rainbow Educational Media
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CREDITS
Author and Producer: Peter Cochran
Costa Rican Production: Audiovisuales Chirripo
Photography: Roberta Miranda
Naturalist/Producer: Werner Andre
Additional Photography: Freestyle Productions
Narrators: Richard Cassell
Randye Kaye
Consultant: John Behler
Curator of Reptiles &
Amphibians, New York
Zoological Society
Curriculum Consultant: Michael Worosz
Stock Video: Encyclopaedia Britannica
European Space Agency
Greenpeace Kaw Valley
Films Leonard Rue
Productions WPA Film
Library National Geographic
Society NASA Oxford
Scientific Films
Post production: North Country Media Audio
Sweetening: Acme Recording Studios
Produced for Rainbow Educational Media by
Cochran Communications
Table of Contents
Introduction...............................................................4
Program Summary.....................................................4
Objectives..................................................................6
Review Questions......................................................7
Activities................................................................... 10
Glossary..................................................................... 14
Bibliography............................................................. 17
Related Videos from Rainbow.................................. 17
Script...........................................................................18
Introduction
Amphibians: Amazing Animals provides students with
an engaging overview of the world of amphibians. It
looks at both common and unusual examples of amphibians that exist today and also looks at the first
amphibians that evolved from their fish ancestors 360
million years ago. It examines characteristics that
different amphibians share and that distinguish them
from other kinds of animals. It also shows unusual
characteristics of specific species of amphibians.
The video is designed to be used by students in grades
five through seven, but older and younger students can
effectively use it as well.
Summary
The opening shows a range of different amphibians
without narration. It is followed by the program title.
After the title, the program describes the characteristics
of amphibians by comparing them to other animals .
Like fish, mammals, reptiles and birds, amphibians are
vertebrates. While mammals and birds are warmblooded, amphibians and reptiles are coldblooded.
Unlike reptiles, however, amphibians have a naked skin.
It is not covered by scales, hair, or feathers.
The program explains that the word "amphibian"
means "double life". Most amphibians start life in an
aquatic environment and move to land.
The first amphibians evolved from fish and crawled
out onto land about 360 million years ago.
Next, the video describes the three types of amphibians that exist now. Caecilians are found only in the
tropics. They look like worms but have teeth. Salamanders are tailed amphibians and usually have four
legs. The program describes how aquatic salamanders
spend their entire lives in water and terrestrial salamanders spend most of their lives on land.
Toads and frogs are the largest group. The greatest
variety of this type are found in tropical rain forests.
Different species are shown, including a red-eyed tree
frog, poison dart frogs and a glass frog. This section
focuses on a variety of features, including color and
markings that may either camouflage a frog or warn
off predators. The program shows how frogs and toads
live in a surprising variety of habitats, even deserts.
The video next describes the reproductive cycles of
frogs, showing mating calls, amplexus (mating embrace and fertilization of eggs), egg laying, and metamorphosis. The stages from larval or tadpole stage to
adult are shown. The program also shows how some
amphibians care for their eggs and some even care for
their young.
The program then describes metamorphosis for salamanders and explains that some salamanders don't
undergo metamorphosis at all. These salamanders
keep their gills.
The next segment of the video shows how many
amphibians are threatened with extinction and cite
factors such as habitat destruction, pollution, and
ultraviolet radiation caused by ozone depletion as
possible causes.
Finally, the video describes ways to help save amphibians. These include preservation of natural habitats,
reducing pollution, and education.
A summary of the key points concludes the program.
Objectives
After seeing the video students should be able to:
1. identify the characteristics of amphibians
2. name and describe the three main types of
amphibians:
frogs and toads
- salamanders
- caecilians
3. describe the life-cycle stages of amphibians
4. describe how amphibians were the first vertebrates to
live on land
5. describe survival adaptations of different
amphibians
6. describe how amphibians are threatened
Review Questions
1. How are amphibians similar to birds, fish, reptiles
and mammals? How are they different? Like these
other animals, amphibians are vertebrates. Unlike
warm-blooded mammals and birds, amphibians
are cold-blooded. Unlike reptiles* amphibians
don't have claws or scales.
2. What may have been the immediate ancestors of
the first amphibians?
Fish, with limbs that enabled them to crawl on the
floor of a swamp or pond.
3. What are some of the characteristics of caecilians?
They have no legs and look like worms. They have
teeth. They are the only amphibians to have
scales, which are tiny.
4. What are some characteristics of salamanders?
They have four legs that are short and sometimes
poorly formed. They have a tail. Some are aquatic
and some of these have gills.
5. What are some characteristics of frogs and toads?
They don't have tails. They can live in a variety
of habitats, including ponds, trees, and even
deserts.
6. How does different kinds of coloring help protect
amphibians from predators? Some have colors that
make it difficult for predators to see them. Others
have bright colors that warn predators that they
are poisonous.
7. What are some features of the red-eyed tree frog
that help it live in trees? They have sticky pads on
their toes that make it easy to cling to branches.
They have long legs that help them climb. They
have eyes that help them see well in the dark..
They have colors and patterns that make it hard
for predators to see them.
8. What are the different ways amphibians breathe?
As larvae they breathe through their gills. After
metamorphosis, they breathe through their skin
and lungs. Some don't develop lungs and breathe
through their skin alone. Some salamanders don't
undergo metamorphosis and continue breathing
through gills as adults.
9. Describe metamorphosis in frogs.
The newly hatched larva, or tadpole, has feathery
external gills. These gills disappear while first
the hind legs and then the front legs develop. The
tail is absorbed into the body, and lungs develop.
10. Describe metamorphosis in salamanders.
Most salamanders lose their external gills. The
front legs develop first and then the hind legs. The
tail grows stronger. Some aquatic salamanders,
however, don't undergo metamorphosis and keep
their gills.
11. Describe differences in parental behavior among
different amphibians.
Some amphibians simply leave their eggs and
have no further involvement. Others, like the
male midwife toad, tend the eggs, and some frogs
tend the developing tadpoles.
12. What are some of the possible causes of a decline in
amphibian populations in recent years? Loss of
habitat as a result of land development, pollution,
and ultraviolet radiation resulting from depletion
of the ozone layer.
13. Why are amphibians good indicators of the health
of the environment?
Amphibians have a thin , unprotected skin that
probably makes them more susceptible to the
effects of pollution.
14. What are some things that can be done to save
amphibians?
Protect their habitats, reduce pollution, educate
other people.
Activities
1. Ask students to research and report on one species
of amphibians. Encourage them to choose a species
not described in the video. Among the questions
their report might answer are: Where does this
amphibian live? What does it eat? Is it nocturnal or
diurnal? How does it reproduce? What traits does it
have that help it survive in its environment?
There are many examples to choose from. Below
are several possibilities.
Caecilians
a. Mexican caecilian: This Central American species doesn't lay eggs. It gives birth to young that are
similar in every respect to adults except that they
are smaller, two to three inches as opposed to 16 to
24 inches.
10
b. Ceylonese caecilian: This caecilian is found in
Sri Lanka . It can lay over 50 eggs. When the eggs
hatch, the larvae head toward a pond or stream
where they remain until they complete metamorphosis.
Salamanders
a. Spotted salamander: Found in eastern North
America from Ontario and Nova Scotia to Georgia
and Texas, this species spends most of its life
underground. Sexually mature individuals migrate
to ponds to breed.
b. Japanese giant salamander: An aquatic species
that is among the largest salamanders.. An adult can
be 39 to 57 inches long (100-144 cm).
c. Mud puppy: This species retains its gills throughout
its life.
d. Olm: This species lives in caves in northeastern
Italy. It has very small eyes covered by its skin,
gills, and is totally white.
Frogs and toads
a. Spring peeper: This frog lives in eastern North
America, from Canada south to Florida. The chorus
of males is regarded as a reliable indicator of the
onset of spring.
11
b.Ornate horned frog: This is a very unusual looking
South American frog because of its large,
bulbous body and short legs. Its bright green skin is
covered with warts.
c. Barking frog: Found in parts of Texas, Arizona,
New Mexico, and Mexico, it gets its name from the
fact that males have a deep call similar to the
barking of a dog.
d. Asian horned frog: Living in the tropical rain
forests of parts of Asia, this frog has pointed appendages on its head that look like horns.
e. Syrian spadefoot: This frog is active at night and
spends its days in burrows it digs with its strong
hind legs.
f. Gray foam-nest tree frog: This African frog
builds foam nests in trees that overhang ponds.
About four or five days after the tadpoles hatch,
they fall into the water where they complete their
larval growth.
g. American bullfrog; This extremely voracious
species feeds on insects, fish, and even other amphibians. The females lay over 20,000 eggs.
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2. Invite a naturalist to talk to the class about amphibians and answer their questions. Often, a naturalist
can bring samples of different types of amphibians
for students to see.
3. Take the class on a field trip to a zoo that includes
specimens of amphibians. Often amphibians and
reptiles are housed in the same area, and this offers
students a chance to distinguish between the unique
characteristics of different specimens of these two
groups.
4. Students can observe the metamorphosis by setting
up an aquarium in their classroom. Tadpoles can be
obtained from a biological supply house such as
Carolina Biological.
5. The acanthostega, which some now believe is a
close ancestor of the earliest amphibians, had not
only limbs but lungs. These enabled it to stick its
head out of the water and breathe air. There are
other examples of ancient lung fish as well as
species that exist today. Ask students to research
and report on these fascinating animals.
13
Glossary
acanthostega fish that may be the closest ancestor of
amphibians
amphibian cold-blooded, smooth-skinned animal of
the class Amphibia, which includes frogs, salamanders,
and caecilians
amplexus mating embrace common to different species of frogs and some salamanders
aquatic living in or near the water
bromeliad type of plant found in tropical rain forests
that has long stiff leaves that form a natural water tank
in which frogs and other animals live
caecilian legless, worm-like amphibian
cold-blooded having an internal body temperature
that fluctuates in response to the outside environment
frog any of many tailless amphibians that can be
aquatic, semiaquatic, or terrestrial
Galapagos tortoise tortoise found on the Galapagos
Islands
gill respiratory organ of most aquatic animals, consisting of a filamentous structure of vascular membranes across which dissolved gases are exchanged
14
ichthyostega one of the earliest amphibians that existed over 360 million years ago
larva newly hatched, earliest stage of an amphibian
mammal any of various warm-blooded vertebrate
animals of the class Mammalia
metamorphosis change in the form of an amphibian
during development after the embryonic stage
midwife toad toad whose male members carry eggs
on its rear legs
ozone gas found in the earth's atmosphere
ozone layer region in the upper atmosphere containing
a high concentration of ozone
poison dart frog tiny Central and South American
frog that secretes poison
red-eyed tree frog Central American tree frog
reptile any one of various cold-blooded vertebrates of
the class Reptilia, such as a snake, lizard, crocodile or
turtle. Has scales rather than a smooth moist skin like
amphibians have
salamander any of various amphibians having scaleless skin, and four, often weak or rudimentary legs
tadpole larva of a frog or toad, having gills and a tail
terrestrial living on land
15
tropical rain forest lowland forest located in the
tropics and characterized by a significant amount of
rainfall
two-toed amphiuma aquatic salamander with poorly
formed limbs
toad a tailless amphibian related to frogs but characterized by a drier, rougher skin
ultraviolet light kind of light in sunlight
vertebrate member of the subphylum Vertebrata,
includes the fishes, amphibians, reptiles, birds, and
mammals; characterized by a segmented spinal column and a distinct, well-differentiated head
warm-blooded having a relatively high and constant
internal body temperature that is relatively independent of the outside environment
16
Bibliography
Cappula, Massimo. Simon & Schuster's Guide to
Reptiles and Amphibians. New York; Simon &
Schuster: 1989.
Caulfield, Catherine. In the Rain Forest: Report from a
Strange, Beautiful Imperiled World. Chicago; University of Chicago Press: 1984.
Clark, Barry. Amphibian. New York; Alfred A. Knopf:
1993.
Crowell, Adrian. The Decade of Destruction. New
York; Henry Holt: 1990.
Lewis, Scott. The Rain Forest Book. Los Angeles;
Living Planet Press: 1990.
Steger, Will and Bowermaster, Jon. Saving the Earth: A
Citizen's Guide to Environmental Action. New
York; Knopf: 1990.
Winner, Cherie. Salamanders. Minneapolis;
Carolrhoda Books: 1993.
Related Videos from Rainbow
Animal Profile Series
Beyond the Bars: Zoos and Zoo Animals
Cool Creatures: Reptiles
Struggling to Survive: Tropical Rain Forests
17
Script Title:
Amphibians: Amazing Animals
Female Narrator:
Most of us have a very limited acquaintance with
amphibians.
We may hear the high-pitched trilling of an American
toad,
or catch a glimpse of tadpoles in a pond.
Sometimes we might see a tree frog, whose coloring
makes it hard to distinguish it from the leaves or bark
of a tree.
For the most part, amphibians are shy animals. Many
stay hidden in the water of a pond or in the soil and
leaves of the ground.
So, there is little wonder that few people are aware of
the amazing variety of amphibians in the way that we
recognize the diversity of more visible animals like
birds, or mammals or even reptiles.
Male Narrator:
In some ways, amphibians are similar to these more
familiar creatures. Like birds, mammals, reptiles, and
fish, amphibians are vertebrates. Being a vertebrate
means that you have a backbone
Mammals and birds, however, are warm-blooded.
This means they generate their own heat and maintain a
fairly constant internal body temperature.
18
Amphibians and reptiles, such as this alligator, are
cold-blooded. A cold-blooded animal's internal temperature varies with the temperature of its environment.
However, there are important differences between
reptiles and amphibians. Reptiles, like this Galapagos
tortoise, have scales that cover their skin.
With minor exceptions, amphibians have a naked skin
that is thin and exposed. Their naked skin distinguishes amphibians also from birds, which have feathers,
and mammals, which have hair.
Female Narrator:
What makes amphibians truly unique, however, is
described by their name. "Amphibian" means "double
life".
Amphibians are born in the water. In the first part of
their lives, they are like fish. They breathe through
gills. In this stage of their lives, like fish they would die
out of water.
But then most amphibians become something very
different. They lose their gills, change their shape, and
move out onto the land.
It is as if they are an entirely different animal. They not
only look different, they occupy a different place in the
ecosystem, eat different things, and behave differently.
19
Male Narrator:
Amphibians have been around for about 360 million
years. Their closest ancestors may have been an unusual fish called the acanthostega. The acanthostega
had limbs which enabled it to crawl along the bottom
of a pond or swamp. In addition to gills, it had lungs
that allowed it to stick its head out of the water and
breathe air.
The first amphibian may have been the ichthyostega,
which looked a lot like its fish ancestors but used its
legs to crawl out of the water.
Amphibians were the first four-legged vertebrates to
inhabit the land. These early amphibians were the
ancestors of all other land vertebrates.
Female Narrator:
Today, there are fewer kinds of amphibians than
existed millions of years ago.
The rarest are the caecilians. There are around 165
different species of caecilians, which live only in the
tropics.
Few people have seen these strange creatures. They
look like worms and spend most of their lives burrowed in the earth. Unlike any worm, however, caecilians
have sharp teeth.
Caecilians are also unique among amphibians in that
they have tiny scales in their body rings.
20
Male Narrator:
Salamanders, a second type of amphibian, are more
common. Worldwide, there are about 360 different
species of salamanders, which are sometimes called
tailed amphibians.
Salamanders are often mistaken for lizards, which are
reptiles. Lizards, like salamanders, have long bodies
and tails and short legs.
But unlike salamanders, lizards have scales and claws,
and their skin is dry. A salamander's skin is moist and
smooth, and salamanders do not have claws.
Female Narrator:
Some salamanders are aquatic, which means they live
their entire lives in the water. This two-toed amphiuma
has poorly developed legs. Like other aquatic salamanders, it breathes through gills and its thin skin.
Other salamanders are terrestrial. They live most of
their lives on land. Some breathe with lungs and
through their skin, but many salamanders never develop lungs.
Even terrestrial salamanders can survive only in a
damp environment. They need to keep their skin moist in
order for oxygen to pass into their bodies.
Salamanders have short legs that stick out to the sides
and are poorly suited for walking long distances.
21
When they move, they sway their bodies back and
forth to wriggle forward; but in the water, a
salamander's long tail acts as a flipper, and even a
terrestrial salamander is a graceful swimmer.
Male Narrator:
Salamanders are carnivores. They eat other animals
such as worms, insects, and small fish.
Salamanders are themselves food for predators such
as birds, fish, snakes, and foxes.
Many salamanders have drab colors that make it
difficult for predators to see them.
However, some salamanders, such as this red eft, are
brightly colored. This coloring warns predators that it
is poisonous to eat.
This slimy salamander has a very unusual way of
defending itself. If attacked, it produces a very sticky
slime that can gum up a predator's mouth long enough
for the salamander to get away.
Female Narrator:
The most common amphibians by far are the frogs and
toads, amphibians without tails. Worldwide, there are
about 3,500 species of frogs and toads. They can be
found on every continent except Antarctica.
Toads are more apt to live on land and have rougher,
drier skin.
22
Frogs are more likely to have smooth moist skin and
live in or near water.
These distinctions don't always apply, and experts
refer to both groups together as just "frogs".
Male Narrator:
Many frogs , of course, live in or near ponds and
streams.
But others, like this red-eyed tree frog in Central
America, live most of their lives in trees.
Tree frogs have toes with adhesive pads that make it
easy for them to cling to a branch or twig. They are
adept climbers. Their long legs and toes help them
move through the thick foliage.
Like many frogs, the red-eyed tree frog has distinctive
coloring that helps protect it from predators like birds
and snakes. The top of its body is green which helps
camouflage its location from predators above it. But
its sides have a distinctive pattern that makes it harder
to see from this angle.
The red-eyed tree frog has large eyes. Its vertical,
catlike pupils help it see well in the dark. It watches for
insects to eat but also is alert to predators that might eat it.
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Female Narrator:
In contrast to the camouflaging colors of the red-eyed
tree frog, poison dart frogs have bright colors and
vivid patterns .
Poison dart frogs usually live in the leaf litter of the
tropical rain forests of Central and South America.
Their bright colors and patterns warn predators to stay
away.
Their poison is secreted by glands just beneath their
skin. This poison is among the most toxic chemicals
known. Even a small amount is enough to kill a large
animal.
Poison dart frogs get their name from the fact that
some native people in South America use their lethal
secretions to coat the tips of their darts and arrows.
Male Narrator:
In many ways, tropical rain forests are ideal habitats
for frogs. There are more species of frogs in these rain
forests than in any other place.
Like all amphibians, frogs need water to keep their
skin moist and these tropical forests get abundant rain.
Some of the water is trapped in plants called bromeliads, and these natural water tanks provide a home for
many frogs. Frogs don't drink the water. They simply
absorb it through their thin skin.
24
One unusual frog in Central American rain forests is
the glass frog. On top, its skin looks like frosted glass.
Underneath, the skin is transparent, letting you see
inside its body.
Surprisingly, there are also species of frogs that survive in very dry climates. This desert frog burrows
into the ground to prevent water loss during long dry
periods, and to keep cool. It comes out only when it
rains to mate and lay eggs.
Female Narrator:
Most amphibians need water to reproduce.
Unlike the eggs of reptiles and birds, amphibian eggs
don't have an outer shell that keeps in moisture. They
need to be in or near water or else they would dry out.
Before a female lays eggs, other things happen.
In most species, the male has a distinctive mating call
to attract females.
When a suitable mate has been found, the male grasps
the female in an embrace called amplexus.
As the female lays her eggs, the male fertilizes them
with his sperm.
Male Narrator:
Each frog egg is surrounded by a jellylike substance.
Inside this jellied mass, larvae, or immature amphibians, form.
25
Eventually, the eggs hatch. Frog larvae are called
tadpoles. After hatching, tadpoles look like fish, and
they breathe through feathery external gills.
After growing a while, a process called metamorphosis
takes place. Metamorphosis means a change in
body appearance. The external gills disappear. A
tadpole still has gills at this point, but they are covered
with a flap of skin.
Then the body becomes more distinct from the tail,
and hind legs form.
Next, front legs form, and the tail is absorbed into the
body. Inside, lungs develop. When it can breathe out
of water, it has nearly completed its transformation
from tadpole to frog.
Here we see a young strawberry poison dart frog that
has completed metamorphosis. Next to it is an adult.
The youth is smaller than a dime.
Female Narrator:
Like frogs, salamanders and caecilians undergo metamorphosis, but the change from the larva, or tadpole,
stage to fully-formed adult is less dramatic.
Like a frog larva, a salamander larva also has feathery
gills. During metamorphosis, however, the body grows
longer and the tail grows stronger, unlike a frog
tadpole whose tail is absorbed into its body: A sala-
26
mander larva's front legs form first, and then the hind
legs.
In most cases, the gills eventually disappear, just as
they do with frogs. However, some species of aquatic
salamanders keep their gills throughout their lives.
Male Narrator:
For many species of amphibians, laying and fertilizing
the eggs is the end of parental responsibility. The eggs
hatch without any tending, and the young tadpoles are
left to fend for themselves.
But other amphibians take a more active role in parenthood. The male midwife toad, for example, wraps the
eggs around his hind legs and carries them everywhere
he goes.
And a poison dart frog may carry tadpoles on its back
while searching for a pocket of water where they can
complete their development.
Female Narrator:
Amphibians are remarkably diverse in how they care
for their young, where they live, what they look like,
and what features help them survive.
But in recent years there has been a worrisome development . Scientists have observed a rapid decline in
populations of many species of amphibians worldwide.
27
Some species have disappeared altogether, prompting
scientists to worry that we are witnessing a mass
extinction.
There have been a variety of explanations for the
disappearance of amphibians. The main problem is
probably humanity. A rapidly growing human population has meant that people have increasingly intruded upon the habitats of amphibians, often reshaping
the landscape to meet their own needs.
Tropical rain forests are one important example. As
we've already seen, these rain forests are home to
many species of frogs. But tropical rain forests are
rapidly being cut down for timber, and to clear land for
cattle ranches and farms.
Rainforests are only one example. In our own country,
ponds are being filled in, rivers and streams dammed,
and roads built to accommodate new developments.
All these things can destroy or damage the habitats of
amphibians.
Male Narrator:
Pollution is another problem. Because of their thin
skin, amphibians may be particularly susceptible to
the effects of air and water pollution .
And amphibians face another peril. Their eggs may be
very sensitive to ultraviolet light, a kind of light that is
28
present in sunlight. In laboratory settings scientists
have proved that when the eggs of certain species of
amphibians are exposed to ultraviolet light, a very
high percentage of them die.
Normally, we are shielded from much of the sun's
ultraviolet light by a chemical in the atmosphere,
called ozone. Ozone forms a protective layer that
blocks much of the sun's ultraviolet radiation.
Using high-altitude planes, scientists have been studying
the protective ozone layer, and many fear it is being
reduced as a result of certain kinds of pollution.
Female Narrator:
Why should we care about amphibians? There are
several reasons.
One reason is simply an appreciation that their different
colors, shapes, and behaviors enrich the diversity of
life on earth .
Another reason is that amphibians are an important
part of different ecosystems. Their loss might have
other consequences. For example, because they hunt
various insects, they help control some insects that
could otherwise become pests.
Amphibians are also the food for other animals that
depend on them for survival. If we lose amphibians,
we risk losing these other creatures as well.
29
Still another reason to care is that there is a lot we can
learn from different kinds of amphibians. For example, poison dart frogs and other amphibians secrete
powerful chemicals. Some of these chemicals are
proving useful as painkillers and other pharmaceutical
drugs.
Finally, amphibians are important indicators of health
of the environment. Because their skin is thin and
unprotected by hair or scales, they may be more
susceptible to the effects of environmental pollution.
Amphibians may be providing early warning signals
that we are seriously damaging our planet. The fact
that so many amphibians are dying off should greatly
concern us, because other species may follow.
Indeed, it would be foolish to believe that the human
species is immune to the effects of the damage we
ourselves do to our planet.
Male Narrator:
In this program, we've seen that over 360 million
years ago, the first amphibians evolved from their fish
ancestors. All other land vertebrates— birds, reptiles,
and mammals—are descended from these amphibians.
Today, amphibians are the most primitive land vertebrates.
30
Some, the wormlike caecilians, are rarely seen. They
spend most of their time burrowed in the soil.
Female Narrator:
Others, the tailed amphibians called salamanders,
have short legs that are poorly suited for walking.
Some salamanders spend their entire lives in water,
breathing through gills and their thin skin.
Male Narrator:
The most common amphibians are the frogs and
toads. Like all amphibians, they need to keep their skin
moist to survive.
Female Narrator:
We've seen that amphibians live in a surprising range
of places. Some spend most of their lives in trees.
Others manage to survive in the desert by burrowing
into the ground to keep moist.
Male Narrator:
We've seen that amphibians are unusual in other
ways. All start their lives as fishlike larvae, but most,
through metamorphosis, change into something very
different.
Female Narrator:
But now these earliest of all land vertebrates are
declining.
31
Their habitats arc being destroyed or poisoned by
pollution.
The depletion of ozone in the atmosphere may pose
other threats to their survival.
Male Narrator:
However, there are things we can do to help amphibians survive. We can support efforts to protect their
habitats.
We can help clean up streams and ponds and other
places that are homes to amphibians.
Finally, we can educate other people about these
amazing animals.
Female Narrator:
By protecting amphibians we help preserve the diversity of living things and the beauty of our natural
world.
THE END
32
CLOZE EVALUATION QUESTIONS
AMPHIBIANS: AMAZING ANIMALS
NAME
DIRECTIONS: Select the answer, from the four choices given, by circling the correct letter.
1. Amphibians are similar to other classes of animals because they also have backbones.
However, they have special characteristics that make them unique. Specifically, their name
means "_____" which accounts for their ability to live on both land and in the water. Most
amphibians are born in the water, develop lungs and live on the land.
1. A. double life
B. one life
C. short life
D. water life
2.
Today, there are fewer kinds of amphibians. One of the rarest type of amphibian is the
These creatures look like earthworms and spend most of their time under the
ground. They have sharp teeth and, unlike other amphibians, have scales. Few people have ever
seen these creatures.
2.
A. frogs
B. salamanders
C. turtles D.
caecilians
3. The second type of amphibian is often mistaken for a lizard. However, _______,
unlike lizards, do not have scales or claws. This creature's skin is moist and smooth and it can
come in a variety of colors.
3.
A. frogs
B. salamanders
C. caecilians D.
toads
4. Salamanders that live in the water breathe through gills just as fish do. These . salamanders
have poorly developed legs but their tails enable them to be excellent swimmers. They will eat small fish and must be careful that they do not become prey to
larger fish and other marine predators.
4. A.
B.
C.
D.
salaman5. The land salamanders can survive only in damp places. These
ders breathe through lungs but must keep their skin moist in order to provide an
adequate supply of oxygen. They have short legs for walking and they sway back and forth as
they move forward. They will eat insects and worms and may have dull colors to camouflage
them in the woodland areas.
5.
6. The third group of amphibians is the most common of all and is found on every continent
except Antarctica. The _____ start their life in water and then develop lungs and live for the
most part on land. Some types spend part of their day in the water looking for insects to eat. In
most cases they have stronger and larger back legs that make them excellent jumpers.
6. A. frogs and toads
B. lizards C.
salamanders D.
newts
7. A. woods B.
rainforests C.
meadows D.
swamps
7. Many frogs need rainy and damp environments in which to survive. In Central America the
_____ provide an excellent habitat for a variety of frogs. Many of the plants that grow there
provide the needed water for survival. Frogs living in this region may have special traits for
survival which include poison in their glands that is quite lethal.
8. Most amphibians need water in which they will reproduce. This process begins with a
familiar mating call by the male frog. When a mate is found, the male grabs the female frog in
an embrace called _____. As the female lays her eggs, the male will then fertilize them with his
sperm. The eggs are laid together in a mass, each frog egg surrounded by a jelly-like
substance.
9. The egg stage is the first in the life cycle of the frog. When the egg hatches, a frog larva
called a the eggs are together in a mass, emerges and starts swimming and looking for food.
These creatures have a large head and large tail for swimming. Like fish, they also breathe
through gills until they grow further and develop lungs. Eventually, they will start to develop
legs and feet, transforming them into frogs.
A. terrestrial B.
marine C.
swamp D.
microscopic
8.
A. grasping B.
amplexus C.
pinning D. latching
9. A. nymph B.
pupa C.
tadpole D. fry
10. A. metamorphosis
B. evolution C.
transformation D.
metabolism
10. Frogs, like other creatures, have distinct stages of development and each state is unique.
This life cycle is called the eggs are together in a mass, and consists of the egg stage, tadpole
stage and adult frog stage. At each of these stages the creature looks completely different
from any of the other stages. Amphibians have a great deal of variety and diversity among
their members.
RAINBOW EDUCATIONAL MEDIA
4540 Preslyn Drive, Raleigh, NC 27604-3177 • Toll free: 1-800-331-4047
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water-like
terrestrial
aquatic
river