Essential Question:

• What is the role of a decomposer in a food web?

Related Benchmarks:

• 912.L.17.9 Use a food web to identify and distinguish producers, consumers, and decomposers. Explain the pathway of energy transfer through trophic levels and the reduction of available energy at successive trophic levels.

Objectives:

• Students will be able to identify decomposers.
• Students will be able to explain the role of decomposers in a food web.

Essential Vocabulary:

• decomposer – a consumer that gets its energy by breaking down dead organisms
• consumer – organism that can’t make its own food to get energy
• food web – shows feeding relationships of an ecosystem in network of food chains
• nutrient – substance that provides food or materials needed for life

Modeled Instruction (Reading passages):

Detritivores are consumers that feed on the “garbage” of an ecosystem. This waste, or detritus, includes organisms that have recently died, fallen leaves, and animal wastes. A vulture is an example of a detritivore. Many bacteria and fungi are detritivores that cause decay by breaking down complex molecules into simpler molecules. So, they are specifically called decomposers. Some of the molecules released during decay are absorbed by the decomposers, and some are returned to the soil or water. Decomposers make the nutrients that were contained in detritus available again to the autotrophs in the ecosystem. Thus, the process of decomposition recycles chemical nutrients.

From Holt Modern Biology

Decomposers break down the complex compounds of dead and decaying plants and animals. They change these compounds into simpler forms that they can use for fuel. Decomposers also break down energy into molecules that are returned to the environment. Some carbon (C) is returned to the air as carbon dioxide (CO2). Plants use the carbon to make more high-energy molecules. A form of nitrogen (N) returns to the soil when proteins are broken down. Plants take in the nitrogen and produce new proteins. Some protozoans, many bacteria, and most fungi are decomposers.

From Glencoe “Science in Review: Mastering the FCAT”

Guided Practice/Independent Practice: Download the concept map - Download the answer key - Review decomposers video