Ecosystems and the Food Chain
The harmony that Rachel Carson wrote about of in
Silent Spring
is an ecosystem. An ecosystem is the way in which plants and animals and the environment live together. In every ecosystem there are food chains . To stay alive all living things need food. Plants get their food from the sun. By using sunlight, green plants make food from carbon dioxide, water and nutrients. Photosynthesis converts energy from the sun into chemical energy that is stored in the cells of plants. Plants and animals use this food. All animals need the oxygen given off by plants in order to breath. Animals called herbivores (plant-eating animals) eat plants for food. Herbivores are known as primary consumers. Carnivores (meat-eating animals) eat herbivores and are secondary consumers. Some carnivores can eat other carnivores and these are known as tertiary consumers. This process is known as the food chain. As the plants and animals die, the decomposers like mushrooms, insects, and worms feed on the decay and break it down into nitrogen and other chemicals. These nutrients enter the soil and provide the plants with food. Plants absorb these nutrients as well as the stored chemical energy from the sun and give them to the herbivores who give them to the carnivores and the chain continues. This food chain is the beginning of harmony in nature. As man evolved the natural balance of the food chain began to change. With our lack of awareness and respect of our environment we are gradually killing ecosystems.
Activity # 3
Design a Food Chain
Show the students several samples of drawings of a food chain. Have the students work in pairs to create an 18 by 24 inch poster of a food chain. The poster should include decomposers, green plants, primary, secondary, and tertiary animals and the sun. Research should be done on what animals are herbivores and carnivores. Display the results.
Materials needed
18 by 24 pieces of poster board,
pencil, markers and rulers.
Students should be given access to the library to find out information about the different animals.
Activity # 4
Have students role play the several parts of a food chain. Let students demonstrate how the food chain can be broken by the use , for example, of insecticides or herbicides. Be sure all major components of the food chain are represented.
