Symbiotic Symbiotic RelationshipsRelationships55thth Grade Science Grade Science

Objectives of the Symbiotic Objectives of the Symbiotic Relationships LessonRelationships Lesson

Students will investigate how organisms or populations Students will investigate how organisms or populations interact with one another through symbiotic interact with one another through symbiotic relationships and how some species have become so relationships and how some species have become so adapted to each other that neither could survive adapted to each other that neither could survive without the other. without the other.

Students will be able to define and identify the following Students will be able to define and identify the following relationships:relationships: ParasitismParasitism MutualismMutualism CommensalismCommensalism

Symbiotic Relationships:Symbiotic Relationships:An IntroductionAn Introduction

Click on the picture of Click on the picture of the leaf cutter at the the leaf cutter at the left or on this link to left or on this link to view a video about view a video about symbiosis.symbiosis.

You must be You must be connected to the connected to the Internet to view this Internet to view this video.video.

Leaf cutter video

Symbiotic RelationshipsSymbiotic Relationships

Definition: A relationship between two Definition: A relationship between two kinds of organisms that lasts over a period kinds of organisms that lasts over a period of time is called symbiosis.of time is called symbiosis.

The word symbiosis can be broken down The word symbiosis can be broken down into two parts to determine its meaning.into two parts to determine its meaning. sym means together (like in the words sym means together (like in the words

sympathy and symphony)sympathy and symphony) bio mean life (like in the words biology and bio mean life (like in the words biology and

biome)biome)

Types of SymbiosisTypes of Symbiosis There are three There are three

types of symbiotic types of symbiotic relationships.relationships. ParasitismParasitism MutualismMutualism CommensalismCommensalism

ParasitismParasitism

Parasitism is the Parasitism is the situation where one situation where one organism benefits organism benefits while the other is while the other is harmed.harmed.

Think of a friendship Think of a friendship where you might feel where you might feel used by your friend.used by your friend.

Parasitic Isopod on fish

CommensalismCommensalism

Commensalism is Commensalism is where one species where one species benefits while the benefits while the second species second species remains unaffected.remains unaffected.

Think of a friendship Think of a friendship where one of the where one of the friends benefits while friends benefits while the other doesn’t the other doesn’t change.change.

Barnacles adhering to the skin of a whale

MutualismMutualism Mutualism is where Mutualism is where

both organisms both organisms benefit from the benefit from the relationship.relationship.

Think of a normal Think of a normal friendship where friendship where both friends gain both friends gain something from the something from the friendship.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.

Now Try thisNow Try thisA lion stalks a herd of antelope wading in a A lion stalks a herd of antelope wading in a pond. A flock of water birds on the shore pond. A flock of water birds on the shore become startled by the sound of the lion’s become startled by the sound of the lion’s approach and fly away with a great deal of approach and fly away with a great deal of noise. The bird’s sudden departure gives noise. The bird’s sudden departure gives warning to the antelope, and they are also warning to the antelope, and they are also able to escape safely. What type of able to escape safely. What type of relationship exists between the birds and the relationship exists between the birds and the antelope?antelope?

a) Mutualismb) Commensalismc)c) ParasitismParasitism

Not quiteNot quite

If the relationship was mutualistic, then If the relationship was mutualistic, then both sides of the relationship would have both sides of the relationship would have a positive result from the relationship. a positive result from the relationship. While the antelope did have a positive While the antelope did have a positive from the birds (the warning) the birds from the birds (the warning) the birds didn’t get a positive from the antelope.didn’t get a positive from the antelope.

Return to the question.Return to the question.

You are CORRECT!You are CORRECT!

In the antelope and water bird In the antelope and water bird relationship, the antelope gets a warning relationship, the antelope gets a warning of the coming danger (+) the water birds of the coming danger (+) the water birds don’t get anything from the antelope don’t get anything from the antelope though.though.

Next exampleNext example

Think about this againThink about this again

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

Return to the question. Return to the question.

For PracticeFor PracticeA lichen is a combination of two organisms, an A lichen is a combination of two organisms, an alga and a fungus. The fungus gets its food alga and a fungus. The fungus gets its food from the alga while the alga gets water from from the alga while the alga gets water from the fungus. This is an example of which the fungus. This is an example of which relationship?relationship?

a)a) MutualismMutualism

b)b) ParasitismParasitism

c)c) CommensalismCommensalism

Good Job!Good Job!

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

It’s interesting that you It’s interesting that you think thisthink this

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

Return to the question.Return to the question.

Can we talk about the Can we talk about the exampleexample

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

Return to the question.Return to the question.