Energy Flow in Food Chains, Food Webs, & Energy Pyramids ECOSYSTEMS
I CAN…. Illustrate energy flow in food chains, food webs, and energy pyramids.
Prior Knowledge • In 3 rd grade you learned about simple food chains, including the roles of producers, consumers, and decomposers. • In 5 th grade you identified the roles of organisms as they interacted and depended on one another through food chains and food webs in an ecosystem. • You learned a lot in 5 th grade. Let’s review what you learned.
• You learned about producers and consumers like herbivores, carnivores, and omnivores. • You learned about decomposers like microorganisms, termites, worms, and fungi. • You learned about the roles of predators and prey. • You also learned about parasites and their hosts.
Future Learning • In high school biology you will learn how to calculate the amount of energy transferred from one level to another in an energy pyramid. • You will also learn the roles that organisms play in the geochemical cycles (such as the carbon cycle, nitrogen cycle, and water cycle). • You will learn more about predation, competition, and symbiotic relationships as well.
Essential Question What does a food chain show us?
Essential Question How does energy flow through an ecosystem?
Food Chains • Food chains use pictures or words and arrows to show the movement of energy through the trophic levels of organisms. • The trophic level of an organism indicates the position that the organism occupies in the food chain. • It shows what it eats and what eats it.
Producers & Consumers The levels are numbered according to how far the particular organism is along the chain. • Producers are at level 1. (Plants are producers because they produce their own food. ) • Herbivores are at level 2. (consumer) • Predators are at level 3. (consumer) And so on…
Anything that cannot make its own food must eat to survive. It must “consume” its food! It is a consumer.
Why does this look more like a “cycle” than a chain? Let’s discuss this one in detail.
Why is the SUN in this picture?
❑ In this food chain, what is the producer? ❑ What is the first level consumer? ❑ What is the second level consumer? ❑ Is the polar bear the 3 rd level consumer? Explain.
This picture shows the trophic levels.
Essential Question How is a food web different from a food chain?
Food Webs • Food webs describe the organisms found in interconnecting food chains using pictures or words and arrows. • In other words, food webs are a bunch of food chains all together! • They describe the complex patterns of energy flow in an ecosystem by modeling who consumes whom or what.
Let’s follow a few food chains found in this food web.
There a lot of arrows here but they’re easy to follow. Try it.
Food Webs are EASY!
Essential Question How does the amount of energy change as it moves through an energy pyramid?
Energy Pyramids • An energy pyramid shows the amount of energy that moves from one trophic level to another in a food chain. • The most energy is available at the producer level of the pyramid. • The availability of energy decreases as it moves up the energy pyramid.
The most energy is at the producer level – the base of the pyramid.
The Energy Pyramid
Who needs the most energy to survive?
Making a Model ❖ Let’s make a model of an energy pyramid. ❖ The model you will construct will be simple. It will show pictures of the producers and consumers at each level, the names in words, and the trophic levels. ❖ The good news is that this model really is perfect for meeting our objectives relating to energy pyramids. ❖ Make sure you follow all instructions for proper completion of the model.