Food Webs

Essential Question
How do different species that live in the same area interact with one another? How is energy transferred from one animal to another?

Objectives

 * Identify the different interspecies interactions
 * Classify animals in a food web into corresponding trophic levels
 * Match species’ relationships into a food web.

Introduction & Student Background
In an ecosystem there are different species that are connected to one another through different interactions. Animals get energy by eating other species, but energy is diluted by 10 percent every time it moves up a trophic level.

Vocabulary
commensalism - when one organism benefits and the other is neither helped nor harmed

mutualism - Occurs when both organisms gain from the relationship

parasitism - one species benefits from the relationship and the other is harmed. Parasitism is not generally fatal to the adversely affected organism.

predation - Killing and/or consumption of one organism by another.

interspecific - existing or occurring between different species.

intraspecific - existing within a species or between individuals of a single species.

photoautotrophs - An organism, typically a plant, obtaining energy from sunlight as its source of energy to convert inorganic materials into organic materials for use in cellular functions such as biosynthesis and respiration.

chemoautotrophs - organisms that obtain energy by the chemical reactions in their environment

Materials

 * Colored Pencils


 * Paper


 * Yarn/String


 * Tape

PREP

 * 1) Find your biome using a biome map: (One is provided here)
 * 2) Find typical animals in your region/biome using a biome food web and print out images of the animals.

ACTIVITY

 * 1) Have students identify what their local biome is based on characteristics that they know of their environment (rainfall, temperatures)
 * 2) Have students choose an animal.
 * 3) Pin/Tape the autotrophs (plants, photo & chem-autotrophs) at the base of the board/table. Arrange the herbivores (primary consumers) above the autotrophs, and the secondary consumers above the herbivores.
 * 4) Form a food web using yarn to connect predator to prey and vice versa.
 * 5) Track energy flow from the autotroph to the highest trophic level/consumer.
 * 6) Add to the food web by using different colors to indicate symbiotic relationships.
 * 7) Identify which species competes against one another by comparing different niches and food sources.

How it fits to Standard

 * See how parts of objects, plants, and animals are connected and work together (2-3)


 * Changes in ecosystems affect the populations that can be supported in a food web.Changes in the ecosystems that can be supported in a food web (4-5)
 * Energy flows through ecosystems from a primary source through all living organisms (6-8)

Follow Up
How did the amount of energy change from one species to another? What was the highest trophic level & longest food chain that you could find?