Constructing Food Webs



There are many different food webs in our world, some containing familiar organisms, others filled with exotic species. Drawing food webs by hand and analyzing them can be difficult. In this Web Quest, you will use the computer to build a food web. You can then easily study the interactions by adding and removing organisms and seeing the result.

This Web Quest will give you insight into how disturbances affect a food web in a particular ecosystem. Every ecosystem has some organisms that are more critical to the health of the system than other organisms. This is critical information for developers, who must be aware of the potential impact of their actions on the health of the ecosystem they are disturbing. You will conduct research on an ecosystem of your choice and then create food webs to determine which parts of the food web are most at risk from disturbance. You will also create a presentation for developers, outlining the potential impacts of disturbance on an ecosystem. You will work in a team, as instructed by your teacher.

Assessment Criteria

Your completed Web Quest will be assessed according to the following criteria:


ask questions about observed relationships
hypothesize the ecological role of biotic and abiotic factors
use a broad range of tools and techniques to gather and record data and information
analyze the interrelationship of biotic and abiotic characteristics that make up an ecosystem
work as members of a team in addressing problems
prepare a suitable informational package, including computer generated food webs before and after a disturbance
justify your conclusions
demonstrate an understanding of pertinent concepts

The Task

In Alberta, development is constantly occurring to accommodate industrial, recreational, and residential needs of the growing population. This development has an impact on the natural environment and on the balance within the ecosystems in that environment. For example, changes to habitat can cause local extinctions, reduce population sizes, and change the breeding habits of some species. These changes can in turn cause changes throughout the food web, which alters the dynamics of the entire ecosystem. Development is inevitable, so developers must understand the impacts they may have when considering a project. This knowledge can help them make decisions that will keep ecosystems healthy.

Your team has been hired by Enviro-Help, an environmental consulting firm, to create an information package on the impact of removing species in an ecosystem. Enviro-Help will then share this information package to developers that are planning new projects in your area.
Your team will conduct research on an undisturbed ecosystem in your area and the organisms in it. You will use this research to help you create a food web (using computer software) that includes all the organisms. You will then remove different species from the food web to model what might happen if the developers were to destroy habitat in the ecosystem. You will need to show what happens when organisms from different levels of the food web change and predict the effects those changes have on the entire food web.

Your team must provide Enviro-Help with an information package that

defines “food web” and explains how a food web works, in language in non-scientific language that a developer could understand easily
shows the food web in the ecosystem in your area
predicts what might happens to the food web if habitat in that ecosystem were to be destroyed and explains why these changes occur.
While you are working, ensure that each member of the team is assigned a different task, such as researching the first order consumers in the ecosystem.
  1. Choose an environment or an ecosystem that interests you, such as deciduous forests, coniferous forests, marshlands, or tundra.
  2. Create a list of the organisms you would typically find in a food web in that environment.
  3. Identify the trophic level of each organism (e.g., producer, primary consumer, secondary consumers, etc.).
  4. Draw a food web for the ecosystem you chose. Use a concept mapping program if it is available. Your teacher will provide specific instruction on the concept mapping program you will be using. Draw food webs by hand if you don’t have access to such a program. Don’t forget to use arrows to show the relationship of the various organisms to each other. Add additional organisms as you continue your research into your ecosystem. If you wish, embed pictures of the organisms and additional notes into you food web. Remember that you want the final web to communicate the information clearly to the developers, who may not have studied biology.
  5. Remove one organism from the food web. Then, predict the effects on any organisms that interact with organism. Draw the predicted food web.
  6. Repeat step 5 for one organism at each trophic level.
  7. Prepare the Information Package. Your team’s information package must include the following:
    (a) a title page that includes the purpose of the package and the names of your team members,
    (b) an introduction that names the ecosystem being presented and the organisms found in that ecosystem,
    (c) the food web of the undisturbed ecosystem which identifies all the trophic levels included and the organisms at each trophic level,
    (d) the predicted food web resulting from the removal of an organism at each trophic level, and an explanation of why the changes are expected to occur,
    (e) a conclusion, summarizing your findings, and
    (f) a recommendation of which trophic level(s) in the ecosystem could be disturbed with the least impact on the rest of the food web.


The following web links will help you to start your research:
bullet Cool Antarctica: Animals
bullet Feeding Relationships
Inspiration Software


Food Web Rubric