Food chains and Webs - hspcrswart.co.za · Various food chains and how they are linked: • Worms,...
Transcript of Food chains and Webs - hspcrswart.co.za · Various food chains and how they are linked: • Worms,...
UNIT 3 FOOD CHAINS AND FOOD WEBS
3.1 Introduction
Living organisms that live together in an environment are interdependent.
These living organisms include plants, animals and humans.
But the environmental conditions, e.g. soil, water and climate also play an important
role. Ecosystems vary in size. Examples are the Kruger National Park, Kalagadi, the
Botanical gardens and the Gariep dam.
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Quick facts: The study of living organisms and the places where they live is called ecology.
There are various habitats in an ecosystem.
Examples:
A cheetah’s habitat is grasslands.
Mopanie worms’ habitat are mopanie trees.
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Ecosystem: An area where living (biotic) and non-living (abiotic) things live and interact with each other.
Biodiversity: The diverse spectrum of life found in one habitat.
Habitat: The area in which plants and animals live.
.
Various plants and animals can be found in each habitat.
The plants and animals in a habitat depend on each other for food and protection
and they form a community.
Communities consist of a variety of populations, such as herds of kudu, flocks of sparrows and schools of fish.
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Community: All the living things in one habitat.
Population: One kind of living organism that is found in one habitat.
3.2 Food chain
Example of a food chain:
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Sun provides energy.
Plants (producers) use this energy to produce their own
food.
Grasshopper (primary consumer) eats the grass.
Frog (secondary consumer) eats the grasshopper.
Frog is eaten by the snake (tertiary consumer).
Snake is then eaten by the falcon.
After the falcon dies, its body is broken down by detritivores and decomposers and
energy is released into the soil, atmosphere and water.
Energy is transferred from one organism to the other in this manner.
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Food chain: It is the relationship where energy (in food) flows between living organisms.
Quick facts: A food chain always has producers and consumers.
Circulation of nutrients :
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Consumers: * primary * secondary * tertiary
Producers
Eaten by Die and are decomposed by
Die and are decomposed by
Detritivores and Decomposers
Consumed by
Used in photosynthesis Nutrients
3.3 Food webs
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Food web: A variety of interlinked food chains.
Various food chains and how they are linked:
• Worms, grasshoppers, mice, guinea fowls and antelope eat grass and plants.
• Herbivores are a source of food for various predators, carnivores and omnivores.
The grasshopper is eaten by the frog and the bird.
The snake catches the mouse.
The genet catches the mouse, frog, guinea fowl, bird and snake.
The antelope is eaten by the leopard.
The genet, guinea fowl and bird are eaten by the eagle.
Because the food chains overlap, a food web exists.
Decomposers are always at the top of the food chain or food web.
Decomposers recycle the nutrients in dead plants and animals and plough it back
into the soil.
These nutrients will make the soil fertile and make it possible for plants to grow.
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Activity 13
Investigate your area. See how many different food chains you can identify and
write them down. Food chains in my environment:
Seed → pigeon/mouse → cat/owl
Flowers → butterfly/moth → spider/gecko → crow
Flowers → plant louse → ladybug → spider → crow
Crops → snale → corn cricket → woodpecker
Crops → mouse → cat/owl
Leaves → worms → hoopoe → cat
Determine how many of these food chains are connected, and then draw your own
food web.
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Seed Flowers Crops Leaves Pigeon Mouse Butterfly Moth Plant-louse Snail Worms
Spider Ladybug Corn cricket Hoopoe
Gecko Wood pecker Cat Crow Owl