Lead students to observe the differences between the two graphics. Ask: Based on this food pyramid, do you think there are more top predators (gray reef sharks, bluefin tuna) than producers (phytoplankton, seagrass, algae)? Why or why not? Then display the Marine Ecological Pyramid and ask the same question. In the Marine Pyramids gallery, display the Marine Food Pyramid. Food chains are often represented as food pyramids so that the different trophic levels and the amount of energy and biomass they contain can be compared. Explain that the shapes of a pyramid and a web are two different ways of representing predator-prey relationships and the energy flow in an ecosystem.

Ask volunteers to come to the front of the room and draw a pyramid and a web. Healthy, well-balanced ecosystems are made up of multiple, interacting food chains, called food webs. In most ecosystems, organisms can get food and energy from more than one source, and may have more than one predator. Review with students that food chains show only one path of food and energy through an ecosystem. Build background about marine trophic pyramids and food webs.

Food chains diagrams