All Things in Balance 5.6.2 Science

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in Balance
by Tamara Jasmine Burrell
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Expository
Nonfi ction
• Balance of
Nature
• Carnivores
• Food Chains
• Herbivores
• Defi nitions
• Diagrams
• Labels
• Glossary
• Latin Word
Parts
• Word Structure
Scott Foresman Reading Street 5.6.2
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All Things
ISBN 0-328-14243-3
in Balance
by Tamara Jasmine Burrell
Editorial Offices: Glenview, Illinois • Parsippany, New Jersey • New York, New York
Sales Offices: Needham, Massachusetts• Duluth, Georgia • Glenview, Illinois
Coppell, Texas • Sacramento, California • Mesa, Arizona
All Things
 Herbivores
Carnivores
cheetah
Thompson’s gazelle
grass
Thompson’s gazelle
Thompson’s gazelles are small antelopes. They live with other
animals in the grasslands of Africa.
Cheetahs eat many kinds of herbivores. They hunt alone or
in groups, called packs. One of the most comon foods for
cheetahs is the Thompson’s gazelle.
Some scales have two sides. When things weigh
the same on both sides, the scale is balanced.
One side does not go up, and one side does not
go down. Nature has a balance, too. What is the
balance of nature?
Let’s begin with a few definitions. Some animals
eat only plants. They are called herbivores. They are
also called plant-eaters or vegetarians. Herbivores
graze on leaves and roots, seeds and nuts, fruits and
grasses. Some of the biggest herbivores live in Africa.
Giraffes, antelopes, zebras, elephants, buffalo, and
wildebeests are all herbivores.
Some animals do not eat plants. They eat other
animals. They are called carnivores. They are also
called meat-eaters or predators. African lions, hyenas,
leopards, and cheetahs are all carnivores. The big cats
and wolves of North America also are carnivores.
The Thompson’s gazelle is one of the cheetah’s
most common meals. The Thompson’s gazelle can run
up to 50 miles per hour. A cheetah can run up to 70
mph. But a cheetah can run that fast for only about
300 yards. After 20 seconds the cheetah gets too hot
and must stop. The gazelle gets away if it can run
faster than the cheetah for more than 20 seconds.
graze on:
eat
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Nature in Balance
The balance of nature usually works well.
Predators eat some plant-eaters. Some plant-eaters
die. Some stay alive. Herbivores eat some of the
plants. The plants have enough soil and water. Most
of the living things stay healthy.
Food Chains
Nature Out of Balance
Nature depends on balance. So what happens
if things get out of balance? If there are too many
herbivores, there may not be enough food. The
animals get thin. They become scrawny. They may
even die of starvation. If the herbivores die, there is
less food for predators. Soon, the predators starve
and die too.
With no animals to eat them, the plants grow
thick. After many years, there are too many plants.
The plants fight for water, soil, and sunlight.
Eventually, they may get sick and die too.
All living things need food. Most plants get their
food from water, dirt, and sunshine. Nutrients and
decaying matter in the dirt, or soil, feed the plants.
Herbivores eat plants. Carnivores eat herbivores or
other carnivores. Each living thing provides food for
other living things in the food chain.
As you go higher in a food chain, there are fewer
kinds of living things. It takes many things at the
bottom of a food chain to support the living things
at the top.
nutrients:
substances such as minerals needed to live and grow
decaying matter:
dead plants and animals that rot in the soil
predators:
animals that hunt to eat
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What Upsets the Balance?
At times, a storm or a flood may upset the balance
of nature. Sometimes, humans upset the balance of
nature. Sometimes humans help restore it. Here is
what happened to one animal: the island fox.
The island fox lives in the Channel Islands of
California. This little fox eats insects, birds, eggs,
crabs, and small animals such as the deer mouse. It
also eats fruit, so it is an omnivore. An omnivore eats
both plants and animals.
In the past, this fox had no enemies. Then
humans came to the Channel Islands. They brought
pigs. Some pigs escaped. Now wild pigs live all over
the islands.
Today, the island fox does have an enemy: a
predator called the golden eagle. This eagle comes
to the islands to eat the wild pigs. It eats foxes too.
Now, the island fox is endangered. These little foxes
could disappear from our world.
No one wanted to upset the balance of nature
in the Channel Islands. People learned that
changing one thing can change the balance of an
environment. Now people are working there to
restore the balance. It takes careful thought and
hard work to restore the balance.
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