Symbiotic Relationships

Symbiotic Relationships 8th Grade Science

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

Symbiotic Relationships:An 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

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 means life (like in the words biology and biome)

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. Types of Symbiosis

Parasitism • Parasitism is the situation where one organism benefits while the other is harmed. • A + / - relationship. Parasitic Isopod on fish

Commensalism • Commensalism is where one species benefits while the second species remains unaffected. • A + / 0 relationship Barnacles adhering to the skin of a whale

Mutualism • Mutualism is where both organisms benefit from the relationship. • A + / + relationship. 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.

Neutralism is the situation where both species remain unaffected. A 0 / 0 relationship. Competition is where neither species benefits. A - / - relationship. Neutralism and Competition

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 lion’s approach and fly away with a great deal of noise. The bird’s 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

Try again • For a relationship to be competition, the end result on both sides of the relationship is a negative. This isn’t the case in this relationship. • Return to the question.

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 didn’t get a positive from the antelope. • Return to the question.

You are CORRECT! • In the antelope and water bird relationship, the antelope gets a warning of the coming danger (+) the water birds don’t get anything from the antelope though. • Next example

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.

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

Let’s 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.

Good Job! • You’re 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

It’s 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.

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.

References • Abbott, D. (2000, May). Retrieved September 22, 2006, from Sybiosis Web site: http://www.ms- starship.com/sciencenew/symbiosis.htm • Examples of Commensalism. Retrieved September 22, 2006, Web site: http://www.cbu.edu/~seisen/ExamplesOfCommensalism.ht m • Meyer, J. R. (1998, January 3). Symbiotic Relationships. Retrieved September 22, 2006, Web site: http://www.cals.ncsu.edu/course/ent591k/symbiosis.html • Mutualism. Retrieved September 22, 2006, Web site: http://userwww.sfsu.edu/~biol240/labs/lab_03symbiosis/pa ges/mutualism.html • Symbiotic Relationships. Retrieved September 22, 2006, Web site: http://necsi.org/projects/evolution/co- evolution/symbiosis/co-evolution_symbiosis.html

Symbiotic Relationships