Students will make a marine food web that will show energy flow through trophic levels. They will also research the ecology of a number of marine animals from the information sheets provided. This activity will be performed after the PowerPoint presentation that is provided with narrative.

  • Familiarize students with key concepts related to energy flow, trophic levels and ecology of marine organisms.
  • The lesson starts with a short PowerPoint presentation on marine food webs. At the end of the presentation the instructor shows an example of a marine food web made with the pictures that are going to be used during the practice.
  • The instructor divides the class into groups of 2 students. Each group is given (1) a sheet with color images of marine animals belonging to either polar, temperate or tropical marine (coral reef) ecosystems; (2) a sheet with the names of all the animals, in order of their appearance on the picture sheet. Along with the name of each animal there is a description that provides all the ecological information necessary to know to which ecosystem(s) it belongs to and what it feeds on.
  • Each group is asked to build either a polar, a temperate or a coral reef food web. The name of the ecosystem is given on the top of the pictures sheet.
  • The Laboratory Instructions Sheet then walks the students through the activity.
  • Class of maximum 30 students, divided in groups of 2.
  • This activity will take the full 90 minutes, and some students will probably have to finish it during a next class, or as homework. The instructor evaluates the finished food webs, using as guideline the following criteria:
  • Choice of the organism (e.g. a tropical species can not be put in a temperate ecosystem) (1/4 of total score).
  • Relevance of the trophic relationships/energy flow arrows (1/4 of total score).
  • Correct trophic level (1/4 of total score).
  • Complexity: extra points should be given to the more complete/complex food webs. Keep in mind that there are more possible trophic connections in the coral reef ecosystem than the polar seas ecosystem (1/4 of total score).
  • Go through the lab instructions sheet prior to starting the lab.
  • The instructor needs to have good knowledge of the marine animals depicted in the pictures sheet. Many combinations are possible to form a food web, but the instructor should ensure that the webs built by the students are biologically realistic (e.g. an elephant seal will not feed on a tropical parrot fish). Some well-known examples such as the kelp-forest food web can be used to illustrate the “cascading effect” of human impacts on marine ecosystems.

Food Web

Food Web

Lesson Specifics
  • Grade Level: 11th and 12th grade classes.
  • Time Frame: This activity is covered in one lesson meant to last 90 minutes or two lessons of 50 minutes.

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