GOAL:

To develop an understanding of the interdependence of all organisms and the need for conserving natural resources

Living organisms share in a variety of complex interrelationships which are based on interdependence.

Ecology H1.00 To understand how the interrelationship of organisms produces an intricate and complex web of life

1.01 identify producers, consumers, and decomposers.

1.02 cite examples of herbivores, carnivores, and omnivores.

1.03 diagram several food chains among organisms personally observed in nature.

1.04 distinguish between food chain, food web, food pyramid, and food cycle.

1.05 identify the above interrelationships among organisms personally observed in nature and seen on nature programs on public television.

I. Ways Organisms obtain food
A. Producers
B. Consumers
C. Decomposers
II. Types of consumers.
A. Herbivores
B. Carnivores
C. Omnivores
III. Food chains
A. algae--> mayfly nymph---> sunfish---> blue heron
B. grass---> grasshopper---> frog---> bass--->human
C. tree leaves---> elephant
IV. Movement of nutrients through an ecosystem.
A. Food webs
1. Numbers in the web
2. Changes in the web
B. Food pyramids
1. Producers on the pyramid
2. Herbivores on the pyramid
3. Carnivores on the pyramid
4. Omnivores on the pyramid
C. Food cycles
1. Action of decomposers
2. Recycling building blocks

COMPONENT OF SCIENCE: Unifying Concepts of Science

GOAL:

To enable students to acquire scientific knowledge by applying concepts, theories, principles and laws from life/environmental, physical and earth/space sciences.

2.4 INTERACTIONS - At all levels of living and non-living systems, matter and energy act and react to determine the nature of our environment.

2.4a Interactions occur on scales ranging from elementary particles to galaxies.

BENCHMARK: All matter at every level must in some way exchange energy.

BENCHMARK: Human interaction with the biosphere is unique in environmental impact and control.

2.4b Interactions of matter and energy shape our world.

BENCHMARK: Nutrient cycles result from flow of energy through an ecosystem.

TIME REQUIRED:

First classroom connector - one full class period plus additional time for enrichment or independent practice, Second classroom connector - one full class period plus additional time for enrichment and independent practice, Third classroom connector - two full class periods plus additional time for independent practice, Fourth classroom connector - one full class period including review of the entire objective

Poster board and markers, string or twine.

Biological magnification, carnivores, consumers, decomposers, herbivores, food chains, food cycle, food pyramid, food web, omnivores, producers.

This classroom connector addresses Instructional Objectives 1.01, 1.02, and 1.03.

Have all students write the name of a specific organism which, using energy from the sun, can make its own food. (pause) Then have all students write the name of a second organism which might eat their first organism. (pause) Next have all students write the name of a third organism which might eat their second organism. In this lesson we will learn how organisms obtain their food and how nutrients move through a food chain.

Producers make their food, in the presence of light, by the process of photosynthesis. Producers may be thought of as the "makers". (Give varied examples of producers from several habitats.) Some might include oak trees, moss, algae, sun flowers, grass, and corn plants. Have students write the name of any producer.

Consumers sat other organisms for their food. Consumers may be thought of as the "eaters". (Give varied examples of consumers from several habitats.) Some might include insects, jellyfish, snails, amebas, and humans. Have students write the names of any consumer.

Decomposers decay dead organisms or their wastes. Decomposers may be thought of as the "decayers." (Give varied examples of decomposers such as bacteria and fungi.) Have students write the name of any decomposer.

Herbivores are consumers which eat the producers. (Give varied examples of herbivores from several habitats.) Some might include grasshoppers, rabbits, goldfinches, and elephants.) Have students write the name of any herbivore.

Carnivores are consumers which eat animals or other consumers. (Give varied examples of carnivores from several habitats.) Some might include owls, bass, spiders, and tigers. Have students write the name of any carnivore.

Omnivores are consumers which eat both producers and consumers. (Give varied examples of omnivores.) Some might include humans, raccoons, cowbirds, and box turtles. Have students write the name of any omnivore.

Food chains are usually shown in a simple straight line relationship starting with a producer and showing what eats what. (Some of the following food chains may be shown on the chalk board.)

Example A--- A. algae---> mayfly nymph---> sunfish--->blue heron
Example B--- B. grass---> grasshopper---> frog--->bass---> human
Example C--- C. tree leaves---> elephant

(Have all students make a food chain on their paper.)

(Have the students write the names of the following organisms:)

the makers--(Producers)

the eaters--(Consumers)

the decayers--(Decomposers)

plant eaters--(Herbivores)

meat eaters--(Carnivores)

organisms that eat plants and animals--(Omnivores)

(Have all students make one more food chain on their paper.)

(Choose from the following examples:

Students may draw food chains on poster boards.

Students may make other food chains from various habitats (desert, rain forest, grasslands, lake, marsh, woodlands, and others).

Watch any nature programs on public television and identify links on food chains.

Take a field trip and observe links in food chains.

Play "Food Chain Rummy," Project Wild-- (Secondary)

"Owl Pellets," Project Wild -- (Secondary)

"Food Mobile," Project Learning Tree

"Making A Place for Wildlife," The Class Project

Identify food chains in magazine articles such as Ranger Rick, National Wildlife, Tennessee Wildlife, and others.)

OTHER:

Project Wild, Secondary
The Class Project
National Wildlife Week materials

These classroom connector addresses Instructional Objectives 1.04, and 1.05.

In a previous lesson we have learned about food chains. (Have all students make a straight-line food chain naming the links. Next have the students make a second food chain across the first involving one organism in the first chain. Make additional chains which are connected to and cross the previous chains. This net-shaped diagram of connected food chains is called a food web.) In this lesson we will learn about food webs.

A food web is a more complex feeding relationship which shows many inter-connected food chains in an ecosystem. This shows that each organism may eat or may be eaten by many other organisms. This gives rise to a complex, interwoven, series of energy transfers.

Possible Activity: (Ahead of time write the names of several producers and many different level consumers in an ecosystem on separate note cards and place them in a container. Have students stand at various places around the room and draw the name of an organism from the container. Using string, connect organisms which eat or are eaten by other organisms. Most organisms should be connected to several other organisms. The resulting net-shaped tangle shows the complexity of a food web.) Often human activities influence a population in a Food web. Choose one organism in this food web which human activity may influence. (Have that organism drop all strings connected to it.) Other organisms which were connected to dropped strings must also drop their strings. The entire food web collapses. In a food web when one population changes, many other populations change. The numbers in some populations may decrease; others may increase.

(Help students construct on paper a food web which might exist in another ecosystem (grasslands, tundra, desert, deciduous forest, rain forest, coral reef, freshwater lake, or others).

(Have the students write the names to the following:)
1. Name the straight-line relationship that shows what eats what.(Food chain)

2. Many food chains connected in a net shape is a what? (Food web)

3. What happens when one food chain in a food web is disrupted? (Other chains in the web will be effected; the entire web may collapse.)

Students may draw food webs on poster boards. Students may watch many nature programs on public television to see food webs in various habitats.

The same materials listed in lesson one of this terminal objective may be used again in this lesson.

(Have all students draw a straight line, a net-shaped series of inter-connecting lines, and a triangle.) These figures represent feeding relationships and the movement of energy in ecosystems. In the previous lesson we have studied food chains and food webs. In this lesson we will study food pyramids.

A food pyramid is drawn in a triangle shape with the producers on the broad base. The herbivores, first-level consumers, form the smaller second layer of the pyramid. The carnivores, second-level or higher-level consumers, form the continuing smaller upper layers of the pyramid. Omnivores will be at more than one level on the pyramid.

(Have students construct a three-dimensional model of a food pyramid. Make four identically sized equilateral triangles. One will be used for the base. Draw identical divisions on the other three triangles for layers of the pyramid (3 to 5 layers would be best). On one of the triangles show a simple food chain starting with any producer on the bottom layer and consumers on the chain on the upper layers. On a second triangle students may list, draw, or paste pictures of other organisms which may occupy each level.

On the third triangle number (from the top layer going down) 1-10-100-1000-10000 depending on the number of layers. These numbers represent energy changes and will be explained in a later lesson. Tape the four triangles together to form the pyramid.)

(Compare and discuss the pyramids which individuals or groups of students have constructed.)

You have seen that as you move to higher levels on the pyramids, each layer is smaller. This is because the consumers, all their life, are eating many organisms below them on the pyramid. Thus there would have to be many more producers than high level consumers.

(Have students write on a sheet of paper any food chain in their pyramid.

Have students estimate the numbers of the previous link which each organism has eaten in its life.

Example: algae---27-->insect larvae---36-->fish---42-->eagle

Have students multiply all their numbers. Our example shows the average insect larvae eating 27 algae; the average fish ate 36 insect larvae; 27 x 36 = 972. The average eagle ate 42 fish; 972 x 42 = 40,824. Numbers will vary for each student's estimate and for the number of layers on the pyramid. This shows that for one top level consumer, there must be very many lower level consumers and tremendously large numbers at the producer layers on the pyramids.)

(Have students share and explain their results with the class.)

Persistent chemicals such as DDT move through a food chain and up a food pyramid. Often poisons introduced into the environment are taken up into the producer and are eaten by the first level consumer giving it a weak dose of poison. The second level consumer eats many of these weak doses giving it a moderate dose of poison. The third level consumer eats many second level consumers giving it a strong dose of poison. This increasing concentration of harmful chemicals through a food chain is called biological magnification.

It shows why our top level consumers such as bald eagles, ospreys, brown pelicans, peregrine falcons, and many other species are endangered by harmful chemicals in the environment.

(Have students name their top level consumer in the previous activity and explain how many doses of poison it may be receiving using the prior calculations.)

Have students write the answers to the following:
1. Name a triangle shape showing feeding relationships. (Food pyramid)

2. What happens to the numbers of organisms as you move to higher layers on a pyramid? (They decrease)

3. What happens to poisons such as DDT as you move to higher levels on a pyramid? (They become more concentrated)

4. Where are humans located on most food pyramids? (At the top layer)

Have students place a human on different food chains in the previous activities and calculate how many doses of poison the human may be receiving.

The same materials listed in classroom connector one may be used again in this classroom connector.

In previous lessons we have studied food chains, food webs, and food pyramids. (Have students draw a circle. Have them place their pencil at any point on the line and follow the circle around and around until they find the end of the line.) (It never ends.) In this lesson we will study food cycles that also are never ending.

Decomposers such as bacteria and fungi decay dead producers, dead consumers, and wastes of consumers. This action removes these materials from the environment and also breaks them down and recycles them into simpler chemicals which may be used by other producers again.

Point to random students asking each to name the following; "the makers"

(Producers), the eaters (Consumers), other eaters (Consumers), the decayers (Decomposers), the makers, the eaters, the decayers, the makers, the eaters, the decayers, the makers, the decayers, the makers, the eaters, other eaters, the decayers, the makers........"

(You may skip from student to student randomly and can have one student give several answers in a row. Do not stop until you are out of breath from asking for quick answers.)

Why did we keep repeating ourselves? (The food cycle is never ending.) The same atoms and chemicals have been recycled in different living things and in non-living materials on earth since the beginning of life on earth. (Ecological cycles are addressed in Strand D of this project.)

(Have students trace backwards where atoms in their body might have been this morning, yesterday, last month, last year, 5 years ago, 20 years ago, 100 years ago, 1000 years ago, 60,000 years ago, 1 million years ago.

Students should see that atoms making them up have been, many times, in all living and non-living things on the planet earth.

You may also have students explain where atoms which were once in their body are now and predict where atoms in their body now may be in the future using some of the previous time frames.)

(Have the students read, or read to the students, the "Odyssey" and "The Round River" sections from Aldo Leopold's A Sand County Almanac. These have excellent examples of the movement of atoms in food cycles.)

Have students write answers to the following:

1. Name a straight line showing what eats what. (Food chain)

2. Name a net shape showing many food chains. (Food web)

3. Name a triangle shape which shows the movement of energy and materials in an ecosystem. (Food pyramid)

4. Name a never-ending circle shape which shows the movement of chemicals to different organisms. (Food cycle)

(Have students draw on paper or on poster boards a food cycle linking producers, consumers, and decomposers with curved arrows in a circle.)

This is the time this file has been accessed since 11/16/96.

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