Symbiotic Relationships

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Symbiotic Relationships

• 7th Grade Science

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Objectives of the Symbiotic Relationships Lesson

• Students will investigate how organisms or
  populations interact with one another through
  symbiotic relationships and how some species have
  become so adapted to each other that neither
  could survive without the other. (Ohio Academic
  Standards LS 7.1)
• Students will be able to define and identify the
  following relationships
• Parasitism
• Mutualistism
• Commensalism
• Neutralism
• Competition

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Symbiotic RelationshipsAn Introduction

• Click on the picture of the leaf cutter at the
  left or on this link to view a video about
  symbiosis.
• You must be connected to the Internet to view
  this video.

Leaf cutter video
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Symbiotic Relationships

• Definition A relationship between two kinds of
  organisms that lasts over a period of time is
  called symbiosis.
• The word symbiosis can be broken down into two
  parts to determine its meaning.
• sym means together (like in the words sympathy
  and symphony)
• bio mean life (like in the words biology and
  biome)

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Types of Symbiosis

• There are five types of symbiotic relationships.
• Parasitism
• Mutualism
• Commensalism
• Neutralism
• Competition

• Each relationship can be shown using - or 0.
• The chart below shows these relationships.

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Parasitism

• Parasitism is the situation where one organism
  benefits while the other is harmed.
• A / - relationship.
• Think of a friendship where you might feel used
  by your friend.

Parasitic Isopod on fish
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Commensalism

• Commensalism is where one species benefits while
  the second species remains unaffected.
• A / 0 relationship
• Think of a friendship where one of the friends
  benefits while the other doesnt change.

Barnacles adhering to the skin of a whale
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Mutualism

• Mutualism is where both organisms benefit from
  the relationship.
• A / relationship.
• Think of a normal friendship where both friends
  gain something from the friendship.

The clownfish and sea anemone are an example of
mutualism. Although these anemones stun and
devour other species of fish, clownfish are not
harmed. Clownfishes were thought to be commensal
on the giant sea anemones, but there now is
evidence that the aggressively territorial
clownfishes chase away butterfly fishes, who eat
anemone tentacles.
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Neutralism and Competition

• Neutralism is the situation where both species
  remain unaffected.
• A 0 / 0 relationship.
• Think of someone you sit beside but never show
  any emotional either positive or negative.

• Competition is where neither species benefits.
• A - / - relationship.
• Think of someone whom you are constantly at
  battle with.

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Now Try this

• A lion stalks a herd of antelope wading in a
  pond. A flock of water birds on the shore become
  startled by the sound of the lions approach and
  fly away with a great deal of noise. The birds
  sudden departure gives warning to the antelope,
  and they are also able to escape safely. What
  type of relationship exists between the birds and
  the antelope?
• Competition
• Mutualism
• Commensalism
• Parasitism

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Try again

• For a relationship to be competition, the end
  result on both sides of the relationship is a
  negative. This isnt the case in this
  relationship.
• Return to the question.

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Not quite

• If the relationship was mutualistic, then both
  sides of the relationship would have a positive
  result from the relationship. While the antelope
  did have a positive from the birds (the warning)
  the birds didnt get a positive from the
  antelope.
• Return to the question.

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You are CORRECT!

• In the antelope and water bird relationship, the
  antelope gets a warning of the coming danger ()
  the water birds dont get anything from the
  antelope though.
• Next example

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Think about this again

• For a relationship to be parasitic, one organism
  benefits from the relationship while the other
  has negative effects from the relationship. In
  this example the only negative is for the lion,
  but we are looking at the antelope and water
  birds.
• Return to the question.

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For Practice

• A lichen is a combination of two organisms, an
  alga and a fungus. The fungus gets its food from
  the alga while the alga gets water from the
  fungus. This is an example of which relationship?
• Competition
• Mutualism
• Parasitism
• Commensalism

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Lets look at this again

• If this were an example of competition, both of
  the organisms would be effected negatively.
  However, in this example neither organism is
  effected negatively.
• Return to the question.

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Good Job!

• Youre right! This is an example of a mutualistic
  relationship. The alga gains water from the
  fungus and the fungus gains food from the alga.
  Both need each other to live and gain something
  from the other organism.
• Go to the assignment

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Its interesting that you think this

• In a parasitic relationship, one organism gains a
  positive while the other organism receives a
  negative. In this example, neither organism
  receives a negative.
• Return to the question.

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Can we talk about the example

• In a commensalistic relationship, one organism
  gains something positive. The other organism
  remains unaffected by the relationship. In this
  example, both organisms are effected by the
  relationship.
• Return to the question.

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Homework

• For homework, complete the Relationships between
  Organisms Symbiosis worksheet.

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About the Author

• Dave Burkhart is currently the Computer and
  Multimedia Literacy teacher at West Muskingum
  Middle School in Zanesville, OH. Prior to this
  position he taught 7th and 8th grade Science for
  four years. Symbiotic relationships was an area
  of the Science curriculum where information
  appropriate for 7th graders was hard to find.

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References

• Abbott, D. (2000, May). Retrieved September 22,
  2006, from Sybiosis Web site http//www.ms- star
  ship.com/sciencenew/symbiosis.htm
• Examples of Commensalism. Retrieved September 22,
  2006, Web site http//www.cbu.edu/seisen/Examp
  lesOfCommensalism.ht m
• Meyer, J. R. (1998, January 3). Symbiotic
  Relationships. Retrieved September 22, 2006, Web
  site http//www.cals.ncsu.edu/course/ent591k/sym
  biosis.html
• Mutualism. Retrieved September 22, 2006, Web
  site http//userwww.sfsu.edu/biol240/labs/lab_0
  3symbiosis/pa ges/mutualism.html
• Symbiotic Relationships. Retrieved September 22,
  2006, Web site http//necsi.org/projects/evoluti
  on/co- evolution/symbiosis/co-evolution_symbiosis.
  html

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