Mammals, Amphibians, and Reptiles
Mammals are warm-blooded animals. All mammals are covered
either by hair or fur and can be found in many different types of
environments. Cats, dogs, elephants, whales, monkeys, and human
beings are all mammals.
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Mammals are able to keep the temperature inside of
their bodies constant, because they are warm-blooded
animals. Mammals keep their bodies warm by eating,
and they stay cool by sweating. Hair or fur also helps
mammals keep their body temperature constant. Some
mammals, such as American bison, have thicker hair
during winter to keep them warm. However, they shed
some hair and do not have as much during summer so
they can adjust to the hot weather. An interesting fact
about mammals is that smaller mammals lose heat
quicker than larger ones. That means that larger
mammals can stay warm easier than smaller ones.
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Most mammals do not lay eggs. Instead, the young grow inside their
mothers. What makes mammals different from the other creatures is
that mother mammals feed the young with milk. Milk provides
important nutrition for the baby mammals to grow.
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Amphibians are cold-blooded animals with moist skin.
Frogs, toads and salamanders are amphibians.
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Amphibians do not have hair, feathers, or claws. The
word amphibian means living a double life. That is,
amphibians have two stages of life. Most amphibians
start their lives in water. When the young grow up, they
can live both in water and on land.
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Amphibians lay eggs, and a clear, jelly-like substance surrounds
each egg. The eggs are either in water or in damp places to prevent
them from drying out. After hatching, amphibian larvae, sometimes
called pollywogs or tadpoles, live in water. They have gills at the sides
of their heads and they use gills to breathe underwater.
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Amphibians go through a stage called metamorphosis.
Metamorphosis means a complete change of appearance, lifestyle, and
even diet. During this time, most amphibians grow limbs, except for
caecilians. For frogs and toads, their tails disappear. Instead of gills,
most amphibians have lungs to help them breathe after
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metamorphosis.
Are amphibians defenseless because they have soft skin and do not
have claws? No! Poison dart frogs have toxic skin that is brightly
colored to warn predators. Most skin toxins only cause a bad taste to
discourage predators. However, some frogs and toads are quite
poisonous. Salamanders whip their tails to fend off predators. Many
salamanders can break off a part of their tail to distract predators so
they can slip away. Later on, a new tail will grow back!
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Reptiles are cold-blooded animals. They have dry
skin with scales. Indeed, what makes reptiles
different from other animals is their dry, tough skin.
Snakes, turtles, and crocodiles are all examples of
reptiles.
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Some reptiles give birth to live young but all others lay eggs. Reptile
eggs are waterproof and are laid on land. Reptiles usually leave their
eggs unattended. After hatching, baby reptiles are fully developed and
are ready to live alone. Because baby reptiles are easy prey for many
animals, a lot of them do not survive for more than a year. Those that
survive have a long life span. For example, green sea turtles can live
up to 80 years of age.
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1. Which of the following is true about metamorphosis?
Amphibians use lungs to breathe before metamorphosis.
Frogs have tails after metamorphosis.
Caecilians have limbs after metamorphosis.
Amphibians need to go through metamorphosis.
2. Which of the following best describes reptiles?
Most reptiles lay eggs in water.
Reptiles have smooth skin.
Reptiles are cold-blooded animals.
Salamanders are reptiles.
3. Paragraph 2 is mostly about –
why mammals have hair or fur.
how small mammals keep warm.
how mammals keep their body temperature constant.
how the American bison stays warm.
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4. Which of the following statements is not true?
Lizards are amphibians.
Frogs do not have tails after metamorphosis.
Salamanders are amphibians.
All amphibians are cold-blooded animals.
5. Look at the diagram of information from the article.
Click to add text
Covered with hair or fur
Do not lay eggs
Warm-blooded
What belongs in the empty box?
metamorphosis
mammals
reptiles
amphibians
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