The key difference between commensalism and amensalism is that in commensalism, one species is benefited while the other organism remains unaffected, while in amensalism, one species is inhibited or destroyed while the other organism remains unaffected.
Organisms interact with each other in many different ways. Such interactions are responsible for the existence of an ecosystem. In symbiotic interactions, two organisms belonging to different species interact with each other. There are different types of symbiosis, such as mutualism, parasitism, commensalism and amensalism. In commensalism, one organism is benefitted without causing any harm to the other organism. In amensalism, one organism is harmed while the other organism is not affected (neither benefited nor harmed).
CONTENTS
1. Overview and Key Difference
2. What is Commensalism
3. What is Amensalism
4. Similarities Between Commensalism and Amensalism
5. Side by Side Comparison – Commensalism vs Amensalism in Tabular Form
6. Summary
What is Commensalism?
Commensalism is a type of symbiotic interaction. In commensalism, one species is benefited while the second species is not benefited or harmed (not affected). Both partners live together as a positive association. The party that benefits from the interaction is known as the commensal. Commensal receives benefits in different ways such as nutrition, locomotion, shelter, support and food scraps, etc.
Figure 01: Commensalism
The relationship between a sea anemone and a clownfish is a type of commensalism. The sea anemone travels with the clownfish to its destination without harming the fish. Other examples of commensalism are biting lice, fleas, and louse that feed harmlessly on the feathers of birds.
What is Amensalism?
Amensalism is an interaction between two organisms from different species. In amensalism, one species causes harm to the other species without any cost or benefits to itself. Therefore, in amensalism, one party is not affected while the other party is harmed (inhibited or destroyed). This is a type of negative correlation between organisms of two species.
Figure 02: Amensalism
The two basic modes of amensalism are competition and antibiosis. In competition, a larger or stronger organism deprives a smaller or weaker organism of food or living space. In antibiosis, one organism is damaged or killed by the chemical secretion of another organism. An example of antibiosis is that Penicillium secretes penicillin, which kills various bacteria. Another example is that roots of black walnut releases a toxic material (juglone), which destroys other nearby plants. An example of competition is that beetles and goats depend on shrubs for foods. Goats consume shrubs, and it harms beetles. Beetles lose their food, and there is a change of getting eaten by the goats as well.
What are the Similarities Between Commensalism and Amensalism?
- Commensalism and amensalism are two different types of symbiosis that occur between two organisms of different species.
- They are inter-relationships.
- In both interactions, one party is not affected.
What is the Difference Between Commensalism and Amensalism?
In commensalism, one species is benefited while the other organism remains unaffected. But, in amensalism, one species is inhibited or destroyed while the other organism remains unaffected. Therefore, commensalism is a positive interaction, while amensalism is a negative interaction. So, this is the key difference between commensalism and amensalism.
The below infographic tabulates the difference between commensalism and amensalism for side by side comparison.
Summary – Commensalism vs Amensalism
Commensalism is a type of interaction in which one organism is benefitted while the other organism remains unaffected. Amensalism is a type of interaction in which one organism is inhibited or destroyed while the other organism remains unaffected. Hence, commensalism is a type of positive correlation between two species, while amensalism is a type of negative correlation between two species. This is the summary of the difference between commensalism and amensalism.
Reference:
1. “Amensalism.” Meaning, Examples, Categories and FAQ, Vedantu, 31 July 2020, Available here.
2. “Biological Interaction.” Wikipedia, Wikimedia Foundation, 26 Feb. 2021, Available here.
Image Courtesy:
1. “Symbiosis – NatGeo10” By brett jordan (CC BY 2.0) via Flickr
2. “Walnut tree 007” By Copperzine – Own work (CC BY-SA 3.0) via Commons Wikimedia