Teacher Designing Food Chains and Food Webs NGSSS: SC.912.L.17.9 Use a food web to identify and distinguish producers, consumers, and decomposers. Explain the pathway of energy transfer through trophic levels and the reduction of available energy at successive trophic levels. AA (Also addresses SC.912.E.7.1, SC.912.L.17.10) Purpose of the Lab/Activity: Differentiate between a food chain and food web. Identify and distinguish the main components of an ecosystem. Explain the pathway of energy through trophic levels. Analyze the reduction of energy available at successive trophic levels. Prerequisites: Understand the role of photosynthesis in ecosystems. A general sense of the major groups of organisms in order to help determine their role and habitat. Know the law of conservation of energy. Materials (per group): butcher paper or poster paper markers Procedures: Day of Activity: What the teacher will do: a. Gather materials for each group, make sure to cut butcher into 1 m 2 sections. b. Tell students that today we will be creating a shoreline food web; set a time limit. c. Review the names of the organisms listed. d. If possible, allow students to search internet for any organisms they may not be familiar with. e. Instead of just having the students write the names of the organisms you Before can create visuals of the organism on index cards. It is a good idea to print activity: a set for each group and laminate them so you can reuse them. f. Student misconceptions should be addressed. Some common misconceptions are: Food chains and food webs are the same. The top of a food chain has the most energy because it accumulates up the chain. Organisms higher in the food-web eat everything that is lower in the food web. Green plants are the only producers. g. Show the students the following video clip: http://videos.howstuffworks.com/planet-green/37343-g-word-pet-pythonsgone-wild-video.htm 1. Create a visual that connects the feeding relationships shown. What the teacher will do: During a. Monitor students during the group assignment to make sure they are activity: remaining on task and are creating a food web. b. Assist groups with identification of organisms from list. Teacher After activity: c. Encourage students to color code organism name according to their role d. Remind students that the arrows(s) that connect the organisms represent the flow of energy. e. Set a 20 minute time limit for group assignment. f. Ask the following questions: 1. Why does the arrow in a food chain point towards the animal that eats the food? 2. What does a food chain have in common with a food web? 3. How is a food chain different from a food web? 4. Identify the following: producers, consumers, decomposers, scavenger, detrivore. What the teacher will do: a. Encourage groups to present their food webs. Check for any possible errors in identifying the organisms’ role. b. Discuss the following questions: 1. What does the suffix “troph” mean? nourish 2. What do you think a trophic level is? The position the organism occupies on the food chain. 3. Compare food chains and food webs. Food webs show how organisms are connected in many ways (via the transfer of energy and matter), food chains follow just one path. 4. Provide an example of a food chain. Answers will vary. (Example: grass frog snake hawk c. Have students complete their individual assignment using their group’s food web. d. Answer Key for Results/Conclusion: 1. Explain what would happen if all of the primary consumers became extinct. The population of secondary and tertiary consumers would decrease since they would not have a food source, and the population of the producers would increase since they would not have a predator. 2. Predict what would happen if a non-native species is introduced into the food web. Introduction of a non-native species could affect the population of the native species. If they could survive in their new environment, they would have no natural predators therefore giving them an advantage. For example the pythons introduced in the Everglades are eating the Everglades endangered and threatened species. Reference the video shown prior to beginning lab. 3. Explain why food webs with many species (biodiverse) are more resilient than those with few species. If the food web only has a few species, the loss of one species would have a greater impact on the other parts of the food web. 4. In theory, the earth could support many more people if we ate at a lower trophic level. List 2 benefits of doing this. Answers may vary. Examples: fewer acres are needed to support a single human, do not consume as many toxins as organisms that eat higher up in the food chain, could support a larger population of humans. List 2 drawbacks of eating lower on the food chain. Answers may vary. Examples: supporting a larger human population Teacher leads to greater pollution, more areas being used for agriculture can lead to loss of biodiversity 5. Large predatory fish usually are found at the 3 rd or 4th trophic level of an energy pyramid. What does this mean in terms of energy loss? Due to the general rule that 10% of the energy in one trophic level transfers to the next trophic level. The further along the food chain you go, the less food (and hence energy) remains available. Extension: Gizmo: Food Chain Teacher Designing Food Chains and Food Webs NGSSS: SC.912.L.17.9 Use a food web to identify and distinguish producers, consumers, and decomposers. Explain the pathway of energy transfer through trophic levels and the reduction of available energy at successive trophic levels. AA (Also addresses SC.912.E.7.1, SC.912.L.17.10) Background: (Source: www.epa.gov) All organisms in an ecosystem need energy to survive. This energy is obtained through food. Producers obtain energy by making their own food whereas consumers must feed on other organisms for energy. This dependence on other organisms for food leads to feeding relationships that interconnect all living things in an ecosystem. A food chain illustrates the simplest kind of feeding relationship. For example, in a forest ecosystem, a grasshopper feeds on plants. The grasshopper is consumed by a spider and the spider is eaten by a bird. Finally, that bird is hunted by a hawk. A food chain clearly shows this pathway of food consumption. You could probably think of another food chain for a forest ecosystem. In fact, many different food chains exist in ecosystems. Although there are many different kinds of food chains, each food chain follows the same general pattern. A link in a food chain is called a trophic, or feeding level. The trophic levels are numbered as the first, second, third, and fourth levels, starting with the producers. Each of the trophic levels is occupied by a certain kind of organism. Producers are always in the first trophic level since they do not feed on another organism. Consumers occupy the rest of the trophic levels. The second trophic level is the first consumer in the food chain and is called a primary consumer. Primary consumers eat plants and are therefore herbivores or omnivores. The next consumer in the food chain is the secondary consumer. The secondary consumer is in the third trophic level. Since the secondary consumer feeds on another animal, it is a carnivore or an omnivore. Similarly, the tertiary consumer occupies the fourth trophic level, and is a carnivore. The last link in a food chain is also referred to as the top carnivore since it is at the top of the food chain and is not hunted by other animals. Teacher Problem Statement: Are food chains and food webs the same? How do organisms transfer energy? Vocabulary: food chain, food web, producer, consumer, decomposer, energy transfer, trophic level Materials (per group): butcher paper or poster paper markers Procedures: You will use the cards below and the information on the cards to construct a food web. Please follow the checklist below to demonstrate mastery of this standard. Your grade will be determined as follows: 1. Number of Organisms a. 4 producers b. 3 primary consumers c. 2 secondary consumers d. 1 tertiary consumer 2. Method of nutrition identified for each organism a. Autotroph or Heterotroph b. Herbivore, Carnivore, or Omnivore 3. Type of consumer identified if necessary a. Primary b. Secondary c. Tertiary 4. Organisms are arranged according to proper trophic levels. 5. Arrows indicate the direction of energy transfer a. Must be in the proper direction b. Must be easy to follow c. Must be correct according to the information provided on each card Results/Conclusion: 1. Explain what would happen if all of the primary consumers became extinct. 2. Predict what would happen if a non-native species is introduced into the food web. 3. Explain why food webs with many species (biodiverse) are more resilient than those with few species. 4. In theory, the earth could support many more people if we ate at a lower trophic level. a. List 2 benefits of doing this. b. List 2 drawbacks of eating lower on the food chain. 5. Large predatory fish usually are found at the 3rd or 4th trophic level of an energy pyramid. What does this mean in terms of energy loss? Teacher Assessment Activity Self-Assessment Teacher Assessment Number of Organisms 1 point for each correct organism 10 Total Method of Nutrition 1 point for each correctly labeled organism 10 Total Type of Consumer 2 points for each correctly labeled consumer 12 Total Proper Arrangement 1 point for each properly placed organism 10 Total Arrows All arrows in proper direction 10 pts Easy to follow 5 pts Correct according to card 10 pts Results/ Conclusion 2 points for each correctly answered question Total: ____/77 Total: ____/77 Comments:___________________________________________________________________ ____________________________________________________________________________. Teacher Bee Eats: Nectar from: Poppy, wild rose, berry Produces: Honey Aphid Eats: Wild rose, poppy, berry Millipede Raccoon Eats: Grass, Fruit Produces: Compost Eats: Praying Mantis, Millipede, Butterfly, Berry, Worm, Fruit Grasshopper Hawk Eats: Fruit, Grass Eats: Mouse, Butterfly, Spider Bear California Blackberry Eats: Fox Hawk Mouse Berry Honey Needs nutrients from the soil. Produces energy by photosynthesis. Mouse Tarantula Eats: Berries Fruit Grass Eats: Mouse Cockroach Worm Butterfly Grasshopper Teacher California Native Grass Praying Mantis Eats: Aphid Grasshopper Needs nutrients from the soil. Produces energy using photosynthesis. Ladybug Eats: Aphid Wild Rose Needs nutrients from the soil. Produces energy using photosynthesis. Deer Mosquito Eats: Poppy Wild Rose Grass Eats blood from: Deer Raccoon Rabbit Mouse Cockroaches Worm Eats: Fruit Nutrients from the soil. Eats: Fruit and Grass Produces: Soil Teacher Fox Eats: Hawk Mouse Butterfly Berry Tarantula California Poppy (nectar) Needs: Nutrients from the soil. Produces energy using photosynthesis Butterfly Fruit Flower Eats: Poppy nectar, Fruit Produces pears Gets nutrients from the soil. Produces energy using photosynthesis.