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Symbiotic Relationship/Interdependence

Lesson Plan

Symbiotic Relationship/Interdependence

Objectives

In this lesson, students learn about different types of symbiotic relationships, and examine the symbiosis between fig trees and fig tree wasps in detail. Students will:

  • describe various types of symbiotic relationships between organisms.
  • explain the evidence scientists have found about the history of the relationship between fig trees and fig tree wasps.

Essential Questions

Vocabulary

  • Symbiosis: A close relationship between organisms of different species that live together.
  • Mutualism: A type of symbiosis in which both species benefit from the relationship.
  • Parasitism: A type of symbiosis in which one species benefits and the other is harmed. The parasitic species lives in or on the host species.
  • Commensalism: A type of symbiosis in which one species benefits and the other is unaffected.

Duration

45–60 minutes/1–2 class periods

Prerequisite Skills

Prerequisite Skills haven't been entered into the lesson plan.

Materials

www.sciencedaily.com/releases/2010/06/100615191649.htm (If computers with Internet access are not available for students, make enough copies of this article for groups of 2–3 students.)

Related Unit and Lesson Plans

Related Materials & Resources

The possible inclusion of commercial websites below is not an implied endorsement of their products, which are not free, and are not required for this lesson plan.

  • Video: Mutual Dependence (figs and wasps)

www.pbs.org/wnet/nature/episodes/the-queen-of-trees/video-mutual-dependence/1359/

  • Figs and Their Wasps

http://cloudbridge.org/fig-wasp.htm

  • Interaction of Figs and Fig Wasps

www.figweb.org/Interaction/index.htm

  • The Calimyrna Fig and Its Pollinator Wasp (with photographs)

http://waynesword.palomar.edu/pljune99.htm

  • The Strangler Fig

http://cloudbridge.org/strangler.htm

  • Examples of symbiotic relationships

http://101science.com/Symbiosis.htm

Formative Assessment

  • View
    • During the class discussion, orally assess students’ ability to classify symbiotic relationships.
    • Collect and check students’ work on Types of Symbiosis handout (S-7-3-3_Types of Symbiosis-Teacher Version.doc).
    • Collect and check students’ paragraphs about fig trees and fig tree wasps.

Suggested Instructional Supports

  • View
    Scaffolding, Active Engagement, Modeling, Explicit Instruction
    W: This lesson focuses on types of symbiotic relationships, especially that of the fig tree and the fig tree wasp.
    H: The warm-up asks students to apply what they know about fig trees and fig tree wasps to predict whether they need each other to survive.
    E: The lesson begins with a whole-class activity in which students identify types of symbiosis. Then, students work individually to complete a handout. Finally, students read the evolution of the fig tree wasp.
    R: After the whole-class activity, students individually complete an activity in which they identify types of symbiosis. Following reading about the evolution of the fig tree wasp, students write an explanation of the evidence scientists have collected.
    E: Students are evaluated based on class participation, their work on the Types of Symbiosis handout, and the paragraph that they write about the evolution of the fig tree wasp.
    T: This lesson can be tailored by providing additional practice with identifying types of symbiosis. Also, students can be directed to the Related Resources about figs and their wasps in order to reinforce understanding of their symbiotic relationship.
    O: The lesson begins with students identifying different types of symbiosis. Then, students apply this to the relationships of fig trees and fig tree wasps, and strangler figs and their host plants. Also, students learn about how scientists are studying the evolution of fig trees and fig tree wasps.

Instructional Procedures

  • View

    Ask students to explain why they think fig trees and fig tree wasps need each other to survive. If needed, they may use their notes from the previous two lessons to help with their explanation.

    Define symbiosis and explain three types of symbiosis: mutualism, commensalism, and parasitism. Have students write the definitions for each type of symbiosis in their notes. Discuss each of the following examples and have students identify each type of symbiosis:

    1.      Clark’s nutcracker and white bark pine (mutualism):

    The trees offer pine nuts as high-energy food to the Clark’s nutcrackers (birds), and so the birds store the nuts in the ground. The nuts that they don’t eat have a good chance of sprouting new pines. If it wasn’t for the trees, the birds would starve, and if it wasn’t for the birds, the trees could no longer reproduce.

    2.      Tubeworms and bacteria (mutualism):

    Certain bacteria and tubeworms living at hydrothermal vents deep in the ocean share a symbiotic relationship. The bacteria live in special cells inside the worm. In exchange for a safe place to live, the bacteria give the worm all the nourishment it needs. They do this by absorbing three ingredients—oxygen, carbon dioxide, and hydrogen sulfide—and then using those ingredients to produce food for the worm.

    3.      Hookworms and human (parasitism):

    Small hookworms live in the intestine of a human. The hookworms feed on nutrients that the human is digesting. They cause the human to become anemic, a condition in which the human does not have enough iron in the bloodstream.

    4.      Barnacles and whale (commensalism):

    Barnacles live on the skin of a whale. The barnacles feed by filtering microscopic plants from the water as the whale swims. The whale is unaffected by the barnacles.

    Distribute the Types of Symbiosis handout and have students complete it individually (see S-7-3-3_Types of Symbiosis-Student Version in the Resources folder).

    Explain the symbiosis between fig trees and fig tree wasps. Fig tree wasps are the sole pollinators of fig trees, and fig tree wasps can only breed in figs. The fig tree wasp crawls into the syconium on the fig tree and moves around, dropping pollen from other fig flowers. The wasp seeks the right part of the flower to lay its eggs. When the wasp larvae hatch, they eat the fig in which they live. The cycle repeats. (See Related Resources for more information on this relationship). Have students take notes on this mutualistic relationship.

    Then, tell students, “Some species of figs are known as strangler figs. The fig grows around a host plant, slowly enclosing it and taking its nutrients. They begin as seeds dropped near the base of a tree by a bird or mammal. The seed sprouts, and the roots that form wrap around the host. This crushes the host tree, and the strangler fig grows strong. What kind of relationship does the strangler fig have with its host tree?” Elicit that this relationship is parasitic.

    If you have computers with Internet access, have groups of 2–3 students read “World’s Oldest Fig Wasp Fossil Proves That If It Works, Don’t Change It” online (available at: www.sciencedaily.com/releases/2010/06/100615191649.htm). If computers are not available, distribute copies of “World’s Oldest Fig Wasp Fossil Proves That If It Works, Don’t Change It” (see S-7-3-3_World’s Oldest Fig Wasp Fossil in the Resources folder). Have each student write a paragraph explaining the evidence that fig trees and fig tree wasps have shared a relationship for over 60 million years.

    Extension:

    • For students who may need opportunities for additional learning, print the Types of Symbiosis worksheet (S-7-3-3_Types of Symbiosis-Student Version.doc) and have them complete the activity for extra practice. It may be helpful to provide them with the following chart to review types of symbiosis (in which “+” means beneficial, “−” means harmful, and “0” means neutral):
    Mutualism + 0
    Commensalism + +
    Parasitism +  

     

    • Students who might be going beyond the standards can create a diagram in addition to writing a paragraph about the fig tree/fig tree wasp relationship. The diagram should show how the wasp reproduces and grows in the fig tree, in the order of its life stages.
         
         
         

Related Instructional Videos

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DRAFT 05/11/2011
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