Unit 7: What is an ecosystem?
Lesson 20
An ecosystem is an area or habitat that contains living and non-living things.
The living and non-living things depend on each other in many different ways.
An ecosystem works like a smooth-running engine, provided people do not interfere with
or harm it.
•
The living things are plants, animals and micro-organisms, such as fungi, moulds
and bacteria.
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The non-living things are air, water, sunlight and soil.
An ecosystem
There are many different ecosystems, such as mountains, grasslands, forests, deserts,
rivers, ponds, wetlands, rocky shores and seas, which all support different kinds of living
things. This term, we will focus on two ecosystems.
Rocky shore ecosystems.
The rocky shore has a lot of wildlife. It is home to animals such as fish, crabs, jumping sea
lice and slow-moving anemones, sea urchins, sea snails and limpets. The rocky shore
ecosystem is also home to animals such as barnacles, limpets and sea anemones, and
plants such as seaweed. At high tide the rocks are covered by water and at low tide the
rocks are exposed to the Sun.
The mussels and barnacles sieve little bits of food from the water when it washes over
them. To protect themselves, they close their shells tightly shut when it is dry. The limpets
eat seaweed. They leave their shells to search for food. Sea birds, such as seagulls and
oysters catchers, catch and then crack open the mussels and limpets.
Rocky Shore
Ecosystem
Commonly found plants and animals in the Rocky Shore
Ecosystem
Activity 20
Draw and label a rocky shore ecosystem.
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Lesson 21
Desert ecosystems.
Desert ecosystems are hot and dry. But, the plants
and animals that make up these ecosystems can
cope with the harsh conditions. Tsamma melons are
an essential plant in the Kalahari’s semi-desert
ecosystem. They look like watermelons, although
they are bitter and do not taste very much like
watermelons. For many animals, though, they are an
essential source of water. The melon vines grow
quickly after the rains, storing the water in their
fruits.
These ripen during the dry winter season, just when
the animals are getting a little thirsty. Brown hyenas,
gemsbok, ground squirrels, striped mice and weaver
birds all depend on the Tsamma melon plants. The
gemsbok dig up the long fat roots for water. The
rodents eat the seeds. The hyenas help to spread the
seeds in their dung. The seeds are nicely hidden and
protected from the rodents. It all fits together well.
Activity 21
Learn more about the rocky shore and desert ecosystems.
1. Draw a desert ecosystem. Search Google images to help you find information.
2. Use the internet to read about and research the rocky shore and desert
ecosystems.
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Lesson 22
Study an ecosystem
Group work.
In Grade 4, you studied a habitat. This year, you are going to look more closely for links
and relationships between the plants and animals and their resources in the habitat.
Aim
In this activity you will look for links between plants and animals in an ecosystem.
Method
Step 1
Select part of an ecosystem on or near the school grounds. Roughly measure an area of
5m by 5m, and mark out the four corners with stones or sticks.
Step 2
Make notes that describe the habitat’s resources, such as food, water, amount of sunlight
and available shelter.
Step 3
Identify and draw three plants and three animals.
Activity 22
Questions
1. Look for signs of feeding on each of the three plants. Identify what has been eating
them and which parts of the plants have been eaten.
2. State what each of the three animals eat.
2.1 ) Name the sort of animal that would eat each of these animals
2.2 ) Explain how these animals and plants depend on each other for food.
3. Identify and describe possible threats to your ecosystem.
(Consider things such as noise, litter, foot traffic, plants cover or wild cats.)
3.1 ) Suggest possible ways to overcome the threat or problem.
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Lesson 23
Activity 23
Find out more about different ecosystems.
Individual work.
Research one of the ecosystems and present it to the class, in the form of a poster.
Include the following:
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The non-living things that support life ( water, air, sunlight, and shelter)
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The living things and the non-living things that are dependent on each other.
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The feeding relationships in the ecosystem.
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The threats to this ecosystem.