Elements of an Ecosystem


An ecosystem is a community of organisms interacting with one another and the environment. It is where all five kingdoms of life com together. An ecosystem may be swamp, ocean , forest or even a rotting tree stomp.

There are various feeding relationships within an ecosystem. the food chain is a model of how energy is passed from one organism to another organism. A food web is the combination of overlapping food chains in an ecosystem.

Symbiosis which simply means living together. de Barry proposed a wide range of associations of organisms in 1879. Phoresis is a specialized form of commensalism in which one organism ( phoront), usually smaller than the other, uses the larger organism as a transport host. Commensalism this is an association of two organisms interact however the association is neither beneficial or harmful for either organism. Mutualism an association of two or more organisms in which all organisms derive mutual benefit. Parasitism is where one organism benefits and the other is harmed. it is important to keep these types of associations in mind wen ever you are looking at the interactions of organisms in the living world.


animal-plant interaction

ant and acacia

picture taken from http://gladstone.uoregon.edu




Lesson 5

Objective: The students will be able to:

*describe organisms relationships within an ecosystem

Engage: Have students brainstorm on what plants and animals live in their community. Do these animals interact with other organisms other than animals? Do they interact with nonliving parts of their environment? Once students have recorded their information and answers, allow the to go on an expedition to study how various organism interact. Record observations and share with class.


Explore: Teacher will make 8x10 sized cards of various consumer, producer, and decomposers for example lions, grass, and bacteria. Be certain that there is an equal number of each card for every type of organism. If possible have a picture of the animal o make it visual and stimulating for the students. Have the cards taped on the wall prior to the students entering the classroom. Once the teacher is ready to begin the activity have the students choose which organism they would like to be and allow them to take the card down off the wall. After every student has a card in there possession arrange students in a large circle. Hand a ball of yarn to the student that possess a producer card like grass. Then interact student to toss the ball of yarn to the student who possess a card that would probably eat the grass for example a grasshopper. That student will then toss the ball of yarn to the next student on the food web for example rabbit. The ball of yarn is continuously passed to the next student on the food web and so on. Once the decomposers have received the ball of yarn it is passed to the next producer to restart the food web cycle and demonstrate the food chain as a cycle of food webs.


Explain: The teacher will explain the concept of a food chain. He/she can give examples of it's importance. The teacher needs to include important vocabulary for the students like decomposer, producer and consumer. Be certain that the students are aware of the various relationships within an ecosystem like symbiosis, comensalism, parasitism, and mutualism. See text Chapter 11 for a reference.


Elaborate: Have students create a food chain. With old magazines have students cut out pictures of animals to illustrate a food web. They may include examples of how human activities or natural disaster disrupt food chains. The students should also use these pictures to demonstrate the various symbiotic relationships various organisms have. For example a students may find a fungus and attach it to a tree to show a parasitic relationship where the fungus benefits but tree looses nutrients to the fungus.


Supplementary Activity: Mycorrhizae is a symbiotic fungi growing on or in the root tissue of plants. It facilitates the entrance of water and nutrients to the plants. For many plants mycorrhizae are essential for survival. For an additional or optional activity have students research mycorrhizae, do a report and present it to the class. You may also show them slides of this organism or have them observe this slide on their microscope.


endotrophic mycorrhiza-photo taken by n.crumpler using video flex camera

Evaluate: The teacher will direct the student to make a record of the foods they have eaten over a week time span. The student will then create a food web or food chain with them at the top. The student will do this for a variety of foods he/she has eaten. They may present this in essay form or to be more creative they may want to make a poster with their pictures and pictures of the organisms the food derived from. The poster may be displayed around the classroom to help the students understand "YOU ARE WHAT YOU EAT!" For example if a student ate beef, a consumer, they would assume the beef ate grass, a producer, that at one point grew from soil which has nutrients from decompsers,