The key difference between detritivores and saprotrophs is that detritivores are a type of decomposers that feed on dead plant and animal matter and then digest them within their bodies in order to gain nutrients and energy while saprotrophs are a type of decomposers that secrete extracellular enzymes into dead organic matter, decompose them and absorb nutrients.
The famous law of physics that states ‘energy can be neither created nor destructed’ can be perfectly applied to the biological world where the energy flows through ecosystems continuously. Detritivores and saprotrophs are important parts of food chains that ensure the energy flow through ecosystems and contribute to the continuance of life. Detritivores and saprotrophs are two groups of organisms involved in decomposing dead biological matter. Although they carry out the same function, there are certain differences between them. Hence, this article mainly focuses on the facts that highlight the difference between detritivores and saprotrophs.
CONTENTS
1. Overview and Key Difference
2. What are Detritivores
3. What are Saprotrophs
4. Similarities Between Detritivores and Saprotrophs
5. Side by Side Comparison – Detritivores vs Saprotrophs in Tabular Form
6. Summary
What are Detritivores?
Detritivores are a type of heterotrophs that feed on dead or organic biomass, including animals, plants, and faeces. Detritivores are essentially able to digest lumps of biomass separately. Hence, most unicellular organisms (bacteria and protozoa) and fungi may not fall into the category of detritivores. However, detritivores should not be confused with decomposers and scavengers.
Detritivores in aquatic environments are bottom feeders such as polychaetes, fiddler crabs, sea star, sea cucumber, and some Terebellids, etc. Earthworm is a classic example of terrestrial detritivores. At the same time, slugs, woodlice, dung flies, millipedes, and most worms are some other examples for detritivores.
Figure 01: Detritivore – Earthworm
Detritivores are recyclers of energy as they act as food sources for consumers such as carnivores. They recycle energy, mainly in forms of carbon, nitrogen, and oxygen. Detritivores ingest decomposing biological matter, digest inside their digestive system, and shed in simple forms. Therefore, plants can easily absorb nutrients from the soil. Therefore, it is clear that detritivores both consume and contribute essential nutrients for both animals and plants.
What are Saprotrophs?
Saprotrophs are heterotrophic organisms that feed on decaying or dead plant matter in the presence of adequate levels of water, oxygen, pH, and temperature. Fungi species predominate among saprotrophs due to their ability to digest lignin in the xylem tissues of plants. It’s also interesting to note that during the Carboniferous period, most dead plants did not undergo decomposition since saprotrophs had not developed the lignin digesting enzymes by then. Hence, these large plant deposits became available for the present day consumption as fossil fuels.
Figure 02: Saprotroph – Fungus
Saprotrophic organisms secrete digesting enzymes such as proteases, lipases, or amylases onto substrates. Extracellular digestion transforms lipids into fatty acids and glycerol; proteins into amino acids, and polysaccharides (e.g. lignin, starch) into glucose and fructose. Fungi absorb these simplified materials into their tissues through endocytosis. Saprotrophs gain nutrition through this method, and it is vital for their growth, repair, and reproduction. Saprotrophs mainly feed on wood, dead leaves, dung, and marine wrack. The ecological role of the saprotrophs is vital for the nutrient cycles or the energy flow of the ecosystems as they consume the matter that is difficult for others to consume.
What are the Similarities Between Detritivores and Saprotrophs?
- Detritivores and saprotrophs are two groups of organisms involved in decomposing organic matter in the soil.
- Both groups constitute of heterotrophs.
- They contribute to recycling nutrients in the ecosystems.
- They make plant nutrients available in the soil.
- Moreover, they occupy a lower level in food chains.
- Because of them, the dead plant and animal organic matter will not accumulate in the environment.
What is the Difference Between Detritivores and Saprotrophs?
Detritivores and saprotrophs are two groups of decomposers. Detritivores are decomposers that consume dead organic matter and digest them internally in their digestive system in order to absorb nutrients. On the other hand, saprotrophs are a group of decomposers that secrete extracellular enzymes on dead organic matter, decompose them and then absorb nutrients in the simplified form. Thus, this is the key difference between detritivores and saprotrophs. Usually, detritivores are mostly animals, while saprotrophs are mostly fungi. Furthermore, detritivores consume lumps of dead organic matter separately, while saprotrophs absorb chemically digested food. Saprotrophs digest their food externally, whereas detritivores do it internally in the digestive system. Thus, this is another difference between detritivores and saprotrophs. Detritivores shed most of the digested matter unabsorbed, whereas saprotrophs absorb the entire digested matter into them for their growth, repair, and reproduction.
Summary – Detritivores vs Saprotrophs
Detritivore is an organism that acts as a decomposer of dead organic matter. They feed on dead plant and animal matter and then digest them within their bodies in order to gain nutrients and energy. In simple words, unlike decomposers, they consume decomposing organic matter, including faecal matter to obtain nutrients. Similar to detritivores, saprotrophs are also decomposers in the environment. But they secrete extracellular enzymes onto dead organic matter and decompose them externally. Then they absorb digested nutrients into their bodies. Thus, this is the difference between detritivores and saprotrophs.
Reference:
1. “Consumers, Detritivores & Saprotrophs.” Alia’s Biology, Available here.
2. Wilson, Andrew W. “Saprotroph.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 21 Nov. 2018, Available here.
Image Courtesy:
1. “Pholiota malicola” By JJ Harrison – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Earthworm” By Dodo-Bird (CC BY 2.0) via Flickr