The Difference Between Food Chains and Food Webs

The Difference Between Food Chains and Food Webs

Organisms get the energy they need from food. A food chain traces the path of energy as it moves from organism to organism in an ecosystem. In most ecosystems, energy begins with the sun, so plants always form the base of a food chain.

Plants, because they can make food through the process of photosynthesis are called producers. The consumer (animal) that eats plants is called the primary consumer. The consumer (animal) that eats the primary consumer is called the secondary consumer. Decomposers are often left out of many food chain diagrams but they are extremely important because they break down dead organisms and release nutrients back into the soil. Examples of decomposers are fungi and bacteria and they should always be the final link in a food chain.

Arrows always show the direction of energy movement in a food chain.

But most organisms are part of more than one food chain. Scientists often use a food web to show a more complete picture of the flow of energy in an ecosystem. A food web is a system of several overlapping food chains.

Label the decomposer,primary consumer,producer and secondary consumer in each food chain below.

Consumers are classified by what they eat. Consumers that eat only plants are called herbivores. Deer, chipmunks and most insects are herbivores. Consumers that eat only animals are called carnivores. Badgers, cougars and wolves are carnivores. A consumer that eats both plant and animals is called an omnivore. Birds, goats and monkeys are omnivores. An omnivore can play more than one role in an ecosystem. For example, a large fish in in a pond will eat both little fish and algae (microscopic plants). When it eats the algae it is a primary consumer. When it eats little fish it is a secondary consumer.

Rules for Food Chains

1. Start with the producer.

2. Determine where the energy from the producer is flowing.

3. Determine where the energy from each consumer is flowing.

4. Draw the arrows in the direction the energy is flowing.

5. End with a decomposer.

Watch the video “What is a Food Chain?”from

On the lines below write two different food chains shown in the video. Don’t forget your arrows!

Watch the food web video and write down 3 things you learned.

______

______

Directions: In the food web below use a different colored pencil to draw in four simple food chains.

Questions:

1. Where does the energy to start a food chain come from? ______

2. What type of organism always starts a food chain?______

3. What type of organism ends a food chain? ______

4. What does a primary consumer eat? ______

5. What does a secondary consumer eat? ______

Name ______period _____

EXIT TICKET

The Difference Between Food Chains and Webs

1. Which type of consumer eats both plants and animals?

A. Herbivore

B. Omnivore

C. Carnivore

2. In the food web pictured to the right, which organisms are herbivores?

A. C and D

B. A and D

C. A and B

3. In the food web pictured which organisms are carnivores?

A. D and E

B. A and D

C. B and C

4. In the food web pictured what is missing?

A. Producers and Consumers

B. Producers and Decomposers

C. The Sun and the Decomposers

5. What would happen to this ecosystem if all the frogs

were killed?

A. The number of producers would greatly increase

B. The number of grasshoppers would greatly increase

C. The number of owls would greatly increase

Name______Period___ Date______

Materials:

Edge of Pond Ecosystem paper, colored pencils

What To Do

1. Use different colored pencils to draw the arrows for at least 3 different food chains.

2. Remember the arrows point in the direction theenergy flows.

3. Draw in the ecosystems energy source.

4. Labe the producers, consumers, and decomposers.

5. Color the picture.

Hints:

Small green algae are plants

Bacteria are found in dirt and soil. They can bedrawninto the picture.

Grasshoppers eat grass

Each food chain ends with a decomposer

Questions:

1. What does the snake eat? ______

2. What does the owl eat? ______

3. What would happen to the rabbit population

if all the snakes in this ecosystem were killed?

______

4. What would happen to the owl population if there

were more rabbits? ______

5. What would happen to the grass around the pond

if there were more rabbits? ______

6. If there were a great many rabbits and they ate all the

grass around the pond what would happen to the

grasshopper population? ______

7. What is the difference between a food chain and a

food web? ______