Wednesday+Dec.+14th

Lesson 2: Symbiotic Strategies
(Adapted from Teachers Domain) toc =Overview= This lesson focuses on symbiosis and ecological relationships. Students will investigate the many ways that species that live in close proximity to each other might interact in an ecosystem, whether via competition or predation or through an ongoing symbiotic relationship such as mutualism, commensalism, or parasitism. Segments drawn from the //Nature// episode "The Secret Lives of Sharks and Rays" and an online interactive featuring the malaria parasite will be used to provide specific examples of these interactions. The students will discover that all ongoing ecological relationships, even parasitic or predatory ones, have evolved over long periods of time and are integral to the maintenance of the balance and stability of an ecosystem.

=Objectives= Students will be able to: =Resources for Lesson 1:=
 * Define and describe the possible ecological relationships between species that coexist in an ecosystem
 * Classify specific interspecies relationships as mutualistic, commensal, or parasitic
 * Understand that ecological relationships evolved over time and are integral to maintaining the balance and stability of ecosystems
 * Name factors that can throw ecosystems out of balance
 * Describe human actions that have contributed to ecosystem imbalance and species decline
 * Suggest remedial actions to ameliorate human-caused imbalances in ecological relationships

Video Discussion Questions: Video Discussion Questions:
 * How does the turtle protect itself?
 * What relationship is held between the tiger shark and the loggerhead turtle?
 * List three ways in which being near a shark might be beneficial to a fish. What is one way that a shark might benefit from a fish (other than as prey)?
 * Classify each shark-fish relationship shown in this video segment as commensalism, mutualism or parasitism.

Video Discussion Questions: Video Discussion Questions: Video Discussion Questions:
 * How have sharks become trained to follow fishermen?
 * Describe how the following species pairs interact in the video segment: fishermen/fish; sharks/fish; sharks/fishermen.
 * Why are shark populations in danger of collapse?
 * How has the relationship between sharks and humans changed over time?
 * What might happen if the shark fin trade continues unchecked?
 * Describe the type of tourism seen in this clip.
 * What benefit do these businesses provide to: sharks? To local populations? To tourists?
 * How might these businesses help prevent the collapse of shark population?

=Materials= For each student:

For the teacher: One computer with Internet access for class demonstration

Web Sites:

www.edline.net www.teachersdomain.org www.youtube.com

=The Lesson=

Part I: Introductory Activity
1. Clear some room on the classroom whiteboard or on a sheet of posterboard. Review students’ knowledge of different ecological relationships by asking them to generate a list of types of interactions that might exist between different species living close to each other. Write these on the board (for example, Species A might eat Species B, Species A might use Species B’s discarded shell for shelter, etc.) NOTE - the list should focus on interactions between different species, not between members of the same species.

2. Ask the students if they can recall a definition for “symbiosis” //(symbiosis is a long-term interaction between different species that interact in close proximity)//. Write the following on the board in three rows: +,+; +,0; and +,-. These symbols represent the three main types of symbiosis. Ask the students if they remember the term for a symbiotic relationship that benefits both species? //(mutualism, +,+)//. What about one that benefits one species while the other species is not affected? //(commensalism, +,0)//. Finally, what about a symbiotic relationship that benefits one species and harms the other? //(parasitism, +,-)//.

3. As a class, see if you can classify the interactions that the students brainstormed in Step 1 as mutualistic, commensal, parasitic, or none of the above. Once you have identified the symbiotic relationships that the students thought of, point out that additional ecological relationships NOT generally considered to be symbiotic include predation //(not a long-term relationship as one species is eaten)// and competition //(not considered to be a direct interaction between species as the focus is a fight over an external resource)//.

Part II: Learning Activity
1. Distribute the //Ecological Relationships Organizer// to each student. Tell your students that they will be watching several video segments that capture ecological relationships between ocean species. They will be making predictions about the relationships between the species and will check their predictions with the information given in the videos.

2. Frame the first video segment by telling the students that they will see a tiger shark and a loggerhead turtle interacting in the waters near the Bahamas. Ask your students to silently make a prediction about the relationship between these two animals and to mark it in the appropriate box of the //Ecological Relationships Organizer//.

3. Provide your students with a focus for media interaction by asking them to check their prediction as they watch the segment. Play segment 1: [|Shark and Turtle] QuickTime Video for the students.

4. Follow up with the students by asking them to name the ecological relationship between the shark and the turtle //(predation)//. Have the students fill in this information on their organizer. Ask the students if anything surprised them about this segment //(accept all answers)//.

5. Frame videos 2 and 3 for your students by explaining that the next segments will show many pairs of oceangoing species interacting. The list of interacting species pairs can be found on the //Ecological Relationships Organizer//. Ask the students to silently predict the relationship they expect to see between each interacting pair of species and to note it on the organizer.

6. Provide your students with a focus for media interaction by asking them to check their predictions as they watch the segment. Give the students a few minutes to fill in the “actual relationship” column in the organizer after viewing the segment, noting the name of the relationship and the description of the behavior observed. You may need to play the video twice for students to record all the information.

7. Play segment 3: [|Sharks and Fishermen] QuickTime Video for the students, asking them to fill in the last row on their organizer. Ask the students to explain if the actual relationships were different than the ones the students predicted.

Part III: Wrap-up & Ticket-to-Leave
1. Instruct students to review the answers on their Distribution Charts with their neighbors. Ask them to explain their original choices and the actual answers. (Write the Ticket-to-Leave Question on the Board while students compare results)

2. Call students back to attention and call on volunteers to explain each video interaction on the chart. Present the T-t-L Question and distribute homework.

Ticket-to-Leave Question:
 * In your own words, describe Symbiosis.
 * Provide an Example of each type of Symbiosis

=Assessment:= (Informal) Student comprehension and attainment will be evaluated as each group shares their findings at the end of class. In addition, the teacher collects and informally assesses the //Ecological Relationship Student Organizers//.

=Homework:= "Suicide Grasshopper" Article Questions: 1. In this article, which organism was the parasite? The Host?

2. What does the parasite cause the host to do?

3. What type of symbiotic relationship is this?

4. What is the benefit of studying hairworms and their ecological relationship to grasshoppers?

"Cordecyps" YouTube Video posted on edline

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