Biology Build a Food Web Activity
Introduction:
Communities are groups of organisms (populations) that maintain persistent associations with each other. The members of a typical community include plants, animals, and other organisms that are biologically interdependent through predation, parasitism, and symbiosis. The structure of a biotic community is largely characterized by the trophic (feeding) relationships among its member species. These relationships are often represented simplistically as afood chain. Each link in the food chain represents atrophic level encompassing either producers or consumers.
In most communities, green plants are the dominantproducers. They represent thefirst levelin a typical food chain. Plants capture kinetic energy from sunlight and, through the process of photosynthesis, manufacture organic molecules (e.g.simple sugars) from carbon dioxide and water. The captured energy is "stored" in the chemical bonds of these molecules.Most of the stored energy is used by plants for their own survival and growth, some is lost as heat, and only a small amount passes on toconsumerswhen the plant is eaten, or to decomposerswhen the plant dies.
Primary consumers occupy thesecond levelof a food chain. These animals, often calledherbivores, survive
by feeding exclusively on plants or plant products. Thethird linkincludesprimary carnivores, secondary consumers that live as predators or parasites of herbivores. Anyremaining levelsin the food chain are occupied by secondary or tertiary carnivores (predators or parasites of other carnivores). Since energy becomes limiting at the uppermost trophic levels, there are seldom more than four or five links in a terrestrial food chain.
As you have learned, a food web is a more accurate depiction of how energy moves through a community of organisms. Food chains show only a single set of energy transfers, ignoring that many organisms obtain energy from many different sources, and in turn may provide energy to many different organisms.
In this activity, you will be building a food web for a mountain foothills ecosystem. You have been provided with images of a number of organisms that are native to the area.
Directions:
1. Cut out the animal icons from the paper provided. Organize them on the blank paper in the proper
hierarchical order of trophic levels. Do not glue them until they are in the proper location.
2. You must use ALL of the icons – no fair making some members of the community disappear. The icons are
not drawn to scale!
3. Using a rulerDraw lines with an arrow moving from each predator to all the prey they
consume. Remember: The arrowhead should point AT the organism that is CONSUMING the other
organism. This is the flow of energy through the food web.
4. Along each line connecting two organisms, identify the relationship that exists between the two:
Producer ? Primary consumer
Primary consumer ? Secondary consumer
Secondary consumer ? Tertiary consumer
Consumer ? Decomposer
Producer ? Decomposer
(Are there any relationships that are difficult to describe in the terms given above?)
Adapted from Science Geek