Amensalism: Definition, Types And Examples Of Amensalism


Amensalism is a type of biological interaction between two organisms or two species in which one is neither benefited or destroyed while other organism suffer loss i.e Destroyed or Inhibited. It is a type of (0,-) interaction. Here – ‘0’ Means no effect and ‘-‘ Means negative effect.

In general, It isn’t considered an important interaction as they are accidental and do not benefit the species doing the harm.


In ecosystem, there are two types of Amensalism which are listed below:-

•Compitition:- In this type, Physically well organism deprives weak organism from growth and food.

•Antibiosis:- In this type, An organism is killed by the toxic chemicals produced by another organism.

10 Examples Of Amensalism

We can see lots of examples of amensalism in nature. We just don’t see that interaction from the study point of view. However – Here, we have tried to include 10 examples of Amensalism (NCERT) that occurs in nature:-

1. Simple example of Amensalism is, Grazing cattle and insects. When cattle graze in grass, the insects are consumed by birds while cattle remains unaffected. There is ‘0’ = Cattle and ‘-‘ = insects.

2. One of the most popular example of Amensalism that most of us has listened is, Interaction between Penicillium and Staphylococcus. Penicillium is fungus and staphylococcus is bacteria. They have (0,-) interaction. In this, Penicillium produces a chemical called penicillin which kills bacteria.

3. Smoother crops like Barley, Sorghum and Sunflower do not allow the growth of weeds nearby. Here, Smoother crop is unaffected while weeds suffer loss.

4. Black walnut (Juglans regia) produce a chemical named juglone. This toxic chemical inhibit the growth of plants in surrounding area. This chemical is toxic to plants like apple, tomato and alfaalfa.

5. Trichoderma and Aspergillus: The fungus trichoderma inhibits Prevents the growth of Aspergillus. That’s why – Trichoderma is used as biocontrol agent in organic farming.

6. Tagetes secrete the chemicals that are toxic to soil nematodes.

7. Algal blooms can lead to the death of many species of fishes. However, the algae do not get benefit from the death of those animals.

8. Elephants stepping on ants doesn’t benefit elephants but kills the ants.

9. Pine tree produces allopathic chemical that inhibits the growth of other crops in its surrounding area. Here, Pine is neither harmed nor benefited while other crops are harmed.

Amensalism Examples In The Ocean

From the above examples, we have filtered out the amensalism examples in ocean as follows:-

➡️Algal blooms can lead to the death of many species of fishes. However, the algae do not get benefit from the death of those animals.


Importance Of Amensalism

As amensalism is (0,-) interaction, It is used in controlled of different harmful organisms. Like in case of Penicillium and Bacteria. This helped in antibiotic production. This interaction helped in the invention of Penicillin, one of the most used antibiotic in the world.

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Amensalism Vs Commensalism

Amensalism and Commensalism are just opposite to each other. Here – Amensalism is (0,-) interaction while Commensalism is (0,+) Interaction. So – Commensalism is a type of biological interaction between two organisms or two species in which one organism is neither benefited nor destroyed while other organism is benefited either in space or food. In Commensalism, the organism which gets benefit is called Commensal while other organism which provides benefit is called host.


Example Of Commensalism

1. Lets take the example we discussed in Amensalism i.e Cattle egret bird and grazing cattle. While cattle graze on grass, the insects which were hiding inside the grass get exposed to outer surface and the birds eat them. Here, Bird is benefited while cattle remains unaffected.

2. Orchid plant growing in tree branches. Here – Orchid is benefited while tree remains unaffected. Orchid gets space and gets full sunlight which otherwise orchid need to compete with other plants while growing on soil. In this case, one question may arise, If orchid isn’t growing on soil and plants also remains unaffected (Commensalism), From where it gets water, The answer is: Orchids has a special tissue called “velamen” tissue by the help of which it takes water directly from atmosphere.

3. Clown fish and sea anemone. Sea anemone helps clown fish to get protected from other predators.

4. Sucker fish and Shark. Sucker fish attached to shark by the help of dorsal fin. Shark carry these fishes to the area of good food availability.

5. Whale and Bernacles. Similar interaction like sucker fish and shark.

Final Verdict

Thus – Amensalism and Commensalism are two different biological interaction which are existing in nature from years. These interactions have their own importance for different animal species. This is full information on Amensalism: Definition, Types And Examples Of Amensalism.


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