Food Chains and Food Webs

Interactions in our Environment

Food Chains and Food Webs

Learning Goals: Describe a food chain and the effect of

losing a part of that chain.

Success Criteria: I can describe a food chain/web and

discuss what happens when one part of the food web is lost.

Where do we get our Energy?

All energy in ecosystems originate with the sun. As we learned last lesson, plants absorb energy and turn it into foods such as sugars and starches.

Animals eat the plants and the energy is transferred.

Carnivores and omnivores eat those animals and energy is again transferred.

A food chain is created....

sun grains chicken

Chicken

dinner

Food Chain (def): A sequence that shows how energy and nutrients are transferred from one organism to another in an ecosystem.

Food Chains

The number of “links” in a food chain can vary, but it always starts with a producer and ends with a consumer.Blueber

ry bush bear

dandelion aphid ladybug robin hawk

2 links

5 links:

Food Webs

In real ecosystems, food chains are not that simple.

Producers (plants) are usually eaten by many different consumers (animals) which in turn can be eaten by many other animals.

Food Web (def): A model that shows how food chains in an ecosystem are connected.

A more realistic Food Web

Your Turn.... In your group, create a food web. Work together to think of as many plants

and animals as possible that will be part of your web. Animals/plants must be realistic and links must be accurate (e.g. A bear does not eat a lion!)

You must identify your ecosystem! Your group will have 8 minutes to make

your web. Be ready to present. Which group will have the most

connections?

Changes in Food Chains/Webs

What happens when one species is eliminated from the web? (Discuss as a class)

Changes in Food Chains/Webs If one species is eliminated (e.g. goes

extinct) it affects the other species in that food web.

Sometime other species will die or they may find an alternate source of food.

When any part of a food web is changed the flow of energy is affected in a food web. We will be studying energy flows next.

Let’s Review Food Webs and Introduce Energy Flows

Food Chains, Food Webs and Energy Pyramids in Ecosystems

Food chains/webs show how energy moves from one organism to another but they do not show how the energy is used.

Energy Flow in an Ecosystem

Work with a partner to find the important information and make jot notes about the information on pages 132-134. (Hint: divide the information into headings, following the text and use diagrams to help you illustrate and understand)