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Page history last edited by gerryc 14 years, 9 months ago

E2. A community has several trophic levels.


Student Outcome: E2.1

Give the functions of producers, consumers, and decomposers in a community.


A trophic level is composed of organisms that make a living in the same way, that is they are all primary producers (plants), primary consumers (herbivores) or secondary consumers (carnivores). Dead tissue and waste products are produced at all levels. Scavengers, detritivores, and decomposers collectively account for the use of all such "waste" -- consumers of carcasses and fallen leaves may be other animals, such as crows and beetles, but ultimately it is the microbes that finish the job of decomposition. Not surprisingly, the amount of primary production varies a great deal from place to place, due to differences in the amount of solar radiation and the availability of nutrients and water.


Source: http://www.globalchange.umich.edu/globalchange1/current/lectures/kling/ecosystem/ecosystem.html


  • Producers

Producers are able to produce carbohydrates from the energy of the sun through photosynthesis or, in some instances, from inorganic molecules through chemosynthesis. Because they can produce their own food, producers are also called autotrophs. Producers form the foundation of every food chain because only they can transform inorganic energy into energy that all other organisms can use. On land, plants and photosynthetic bacteria are the main producers. In marine environments, green plants and algae are the main producers. In deep water environments near geothermal vents, chemosynthetic organisms are the main producers.

  • Consumers

Consumers cannot produce the energy and organic molecules necessary for life; instead, consumers must ingest other organisms in order to get these materials. Consumers are also called heterotrophs because they must consume other organisms in order to get the energy necessary for life. There are three types of consumers; the categories of consumers are based on which organisms a particular consumer preys on. Primary consumers, such as sheep, grasshoppers, and rabbits, feed on producers. Since all producers are plants or plantlike, all primary consumers are herbivores, which is the name for a plant-eating animal. Secondary consumers eat primary consumers, making them carnivores—animals that eat other animals. Foxes and insect-eating birds are examples of secondary consumers. Tertiary consumers eat secondary consumers and are therefore carnivores. Polar bears that eat sea lions are tertiary consumers. Consumers that eat both producers and other consumers are called omnivores.

  • Decomposers

Also called saprophytes, decomposers feed on waste or dead material. Since they must ingest organic molecules in order to survive, decomposers are heterotrophs. In the process of getting the energy they need, decomposers break down complex organic molecules into their inorganic parts—carbon dioxide, nitrogen, phosphorus, etc.



Source: http://www.sparknotes.com/testprep/books/sat2/biology/chapter10section3.rhtml


Here is a simulation of the community of coral reef - like the great barrier reef. You are eventually challenged to build a food web on the reef. Yes, it a game!


Too complicated? Try this one!


Here you can choose from three different Australian ecosystems and change the numbers of populations of producers, consumers and top consumers. Noice!


Reasonable introduction to the topic - gets a bit hard to follow though

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Try this one.

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Just because it is so good, here is one on how many consumers feed on krill.


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