Decomposers and Recycling Advanced
Douglas Wilkin, Ph.D.
Jean Brainard, Ph.D.
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Printed: January 4, 2016
AUTHORS
Douglas Wilkin, Ph.D.
Jean Brainard, Ph.D.
www.ck12.org
C HAPTER
Chapter 1. Decomposers and Recycling - Advanced
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Decomposers and
Recycling - Advanced
• Explain how decomposers resupply elements to producers.
What happens to the remains of all the dead organisms?
These are consumed by decomposers, such as bacteria and worms. But buzzards and other scavengers also feast on
these remains. Luckily, these decomposers keep the remains (and wastes) of organisms from piling up in the various
ecosystems. And just as importantly, they aid in the recycling of an abundance of nutrients.
Decomposers
When a plant or animal dies, it leaves behind energy and matter in the form of the organic compounds that make
up its remains. Decomposers are organisms that consume dead organisms and other organic waste. They recycle
materials from the dead organisms and waste back into the ecosystem. These recycled materials are used by the
producers to remake organic compounds. Therefore, decomposers, like producers, are an essential part of every
ecosystem, and their stability is essential to the survival of each ecosystem. In essence, this process completes and
restarts the "circle of life." As stated above, scavengers consume the carcasses of dead animals. The remains of dead
plants are consumed by organisms called detritivores.
Decomposers, producers, and consumers are reviewed in Consumers, Producers Decomposers at http://www.youtu
be.com/watch?v=_Z2SIdzT5jU (4:17).
MEDIA
Click image to the left or use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/181
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Detritivores
When plants drop leaves or die, they contribute to detritus. Detritus consists of dead leaves and other plant remains
that accumulate on the ground or at the bottom of a body of water. Detritus may also include animal feces and other
organic debris. Heterotrophic organisms called detritivores feed on detritus. Earthworms, millipedes, and woodlice
are detritivores that consume rotting leaves and other dead plant materials in or on soil. Dung beetles, like the one
shown in the Figure 1.1, consume feces. In aquatic ecosystems, detritivores include “bottom feeders” such as sea
cucumbers and catfish.
FIGURE 1.1
A dung beetle rolling a ball of feces to its
nest to feed its offspring.
Saprotrophs
After scavengers and detritivores feed on dead organic matter, some unused energy and organic compounds still
remain. For example, scavengers cannot consume bones, feathers, and fur of dead animals, and detritivores cannot
consume wood and other indigestible plant materials. Organisms called saprotrophs complete the breakdown of
any remaining organic matter. The main saprotrophs that decompose dead animal matter are bacteria. The main
saprotrophs that decompose dead plant matter are fungi. Fungi are also the only organisms that can decompose dead
wood. Single-celled protozoa are common saprotrophs in aquatic ecosystems as well as in soil.
Saprotrophs convert dead organic material into carbon dioxide and compounds containing nitrogen or other elements
needed by living organisms. The elements are then available to be used again by producers for the synthesis of
organic compounds. The main characteristic that differentiates detritivores from saprotrophs is that saprotrophs
secrete enzymes that digest dead material externally, whereas detritivores digest internally.
Banana Slugs: The Ultimate Recyclers
One of the most beloved and iconic native species within the old growth redwood forests of California is the Pacific
Banana Slug, the unique mascot of the University of California, Santa Cruz. These slimy friends of the forest are
the ultimate recyclers, playing a crucial role in that ecosystem. Feeding on fallen leaves, mushrooms, or even dead
animals, the slugs play a pivotal role in decomposition. The unique niche of these creatures is critical in replenishing
the soil and maintaining the ecosystem. QUEST goes to Henry Cowell Redwoods State Park near Santa Cruz,
California on a hunt to find Ariolomax dolichophallus, a bright yellow slug with a very big personality. See Banana
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Chapter 1. Decomposers and Recycling - Advanced
Slugs Unpeeled at http://www.kqed.org/quest/television/science-on-the-spot-banana-slugs-unpeeled (6:01) for more
information.
MEDIA
Click image to the left or use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/440
Vocabulary
• decomposers: Organisms that consume dead organisms and other organic wastes.
• detritivores: Organisms that consume the remains of dead plants (detritus).
• detritus: Dead leaves and other plant remains that accumulate on the ground or at the bottom of a body of
water.
• saprotroph: An organism that obtains its nutrients from non-living organic matter, usually dead and decaying
plant or animal matter, by absorbing soluble organic compounds.
Summary
• Decomposers break down dead organisms and other organic wastes in ecosystems.
• Decomposers resupply producers with the elements they need to synthesize organic compounds.
Practice
Use these resources to answer the questions that follow.
• Amazon Animals: Decomposers at http://addiesrainforest.weebly.com/decomposers.html
• What Are Rainforest Decomposers? at http://www.ehow.com/info_8560183_rainforest-decomposers.html
1. Describe the following Amazon decomposers:
a.
b.
c.
d.
Ants.
Termites.
Velvet worm.
Fungi.
2. Which decomposers in the Amazon break down large matter like trees? What happens after?
3. How fast do things decompose in the rainforest?
Review
1. How do decomposers resupply elements to producers?
2. What is detritus? What kinds of organisms consume detritus?
3. What is a saprotroph? Give two examples.
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References
1. Amy Goldstein. http://www.flickr.com/photos/amylovesyah/3945525048/ . CC BY 2.0
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