This unit explores the themes of connectedness and cascading chain reactions in marine food webs. Building from energy conversions to ecosystems, students explore the way relationships between organisms combine to structure an ecosystem. They then apply this knowledge to the question of how whaling affected marine ecosystems, especially at the poles. Students come to understand the concept of “ecological cascades” and learn about the long-term effects of some ecosystem disturbances and that some of these effects may not be reversible. Independent research, presentations, hypothesis testing, and data analysis are used to explore these concepts.

  • Students will know that energy conversions underpin all ecological processes.
  • Students will know that an ecosystem is a collection of organisms and their shared environment that are connected in a food web by the energy exchanged among them.
  • Students will know that some species in a food web are more influential than others in determining ecosystem states.
  • Students will explain how there are no holes in ecology. If you make a hole, something will fill it in.
  • Students will explain how a single ecosystem can exist in many different stable states.
  • Students will be able to provide examples of how humans alter natural systems.
  • Students will practice hypothesis testing as a way to organize assumptions and test them with data.
  • Top predators are the biggest and most important animals in an ecosystem.
  • A keystone species is whatever species is the most abundant or highest in the food chain.
  • Removing only one species or trophic level does not impacting the rest of the ecosystem.
  • Polar ecosystems are vast lifeless areas of ice.
  • Whaling only affected whales, not entire ecosystems.
  • Ecosystems recover quickly from human impacts.
  • Humans are not part of natural food webs and are an exception to ecological rules.
  • This unit involves 3 brief PowerPoint lectures, 1 computer lab for independent research (but materials are provided to substitute this for non-computer-based work), 3 dry labs including food-web construction activities (both drawn and using visual aids), analysis and explanation of figures from scientific literature, and various share-out type activities performed by small student groups.
  • Introduction to marine habitats, online research to build their food webs, and poster presentation to share knowledge. Posters are the basis of Lesson 2 as well.
  • Determine which food web connections are most important to the greater ecosystem. More work with marine habitats and food web posters.
  • Applying knowledge about food web cascade to ecosystems impacted by whaling.
  • Students will be evaluated formatively for comprehension through discussions and hypothesis testing. Rubric for food web presentations and posters are also included in materials. The final lesson on whaling and ecosystems will also assess the students, since it provides students them a chance to apply what they learned in earlier lessons.
  • One product from this unit is that each group will produce a poster of the food web of a classic marine habitat (coral reef, salt marsh, rocky intertidal, kelp forest, hydrothermal vent). This is a good introduction to the kinds of habitats that occur in the oceans, and keeping the posters on the wall can be a helpful reminder for students throughout the rest of the course.
  • In all lessons, students will take notes on brief PowerPoint presentations. Following these lectures, students will engage in group activities (3-5 students per group). These activities include: online research, creating and presenting a poster (Lesson 1), using this poster to engage with new material (Lesson 2) and building hypotheses and flashcard activities (Lesson 3). Handouts and flashcard materials are provided below, with specific printing instructions for each lesson. Color printing is helpful but not required, but double-sided printing is needed.
  • 6. Ecology.
  • 6b. Students know how to analyze changes in an ecosystem resulting from changes in climate, human activity, introduction of nonnative species, or changes in population size.
  • 6c. Students know how fluctuations in population size in an ecosystem are determined by the relative rates of birth, immigration, emigration, and death.
  • 6e. Students know a vital part of an ecosystem is the stability of its producers and decomposers.
  • 6f. Students know at each link in a food web some energy is stored in newly made structures but much energy is dissipated into the environment as heat. This dissipation may be represented in an energy pyramid.
  • 1a. Select and use appropriate tools and technology (such as computer-linked probes, spreadsheets, and graphing calculators) to perform tests, collect data, analyze relationships, and display data.
  • 1d. Formulate explanations by using logic and evidence.
  • 1i. Analyze the locations, sequences, or time intervals that are characteristic of natural phenomena (e.g., relative ages of rocks, locations of planets over time, and succession of species in an ecosystem).
  • 1l. Analyze situations and solve problems that require combining and applying concepts from more than one area of science.
  • 1m. Investigate a science-based societal issue by researching the literature, analyzing data, and communicating the findings. Examples of issues include irradiation of food, cloning of animals by somatic cell nuclear transfer, choice of energy sources, and land and water use decisions in California.

A Crown of Thorns starfish on an Indonesian reef

A mother humpback whale breaching in a Canadian fjord. Photograph by Hermann Meuter, North Coast Cetacean Society

A diverse tide pool in the Pacific northwest
Lesson Specifics
  • Grade Level: 10th grade Marine Biology
  • Time Frame: 4 consecutive days of 90-minute classes, but could easily be extended into more days than that

Scripps Pier

Contact Us

COSEE  |   SERC  |   SIO  |   OSU

Sponsored by NSF and NSDL

◄   Scripps Classroom Connection Home Page