Amensalism is an association between two species where one species is neutral while the other is harmed. It can be seen as a competitive form of interaction between organisms.

It is used to describe the (0,−) interaction in the familiar two-species interaction. It is the interaction of two species in which the impact of one species on the other is negative, but where there is no noticeable impact of the second species on the first.

Types of Amensalism 

The two types are :

  1. Competition
  2. Antibiosis

Now, let’s talk about these in brief.


The two species compete for their survival; this may be over a food resource or survival.

We can see this type of competition between two different species and between the same or same species.

Example: Lion and tiger fighting for an antelope or a deer.


It is a type of biological interaction between two or more organisms where it is detrimental for at least one of them; it is usually due to a secretion of some chemical substance.

These types of Interactions can be seen in between antibiotics & bacteria.

Example: Penicillin secretion by bread mold Penicillium, having a detrimental effect on bacteria. 


Question 1. Define Amensalism.

Solution. It is an interaction between two species where one species is harmed while the other is neither profited nor negatively affected.

Question 2. Is Amensalism a positive interaction or negative?

Solution. Amensalism is a type of interaction in which one species is benefited while the other is harmed.
It can be seen as positive for benefited species & negative for the species that got harmed.


In Which Relationship is One Organism Harmed?

Amensalism is the relationship where one organism is harmed while other organism is profited.

What are two types of Amensalism?

The two types are,
1. Competition
2. Antibiosis 

Is Amensalism a positive-negative interaction?

It is a negative, neutral type of interaction, where one species is affected while the other stays neutral.

How is amensalism different from parasitism?

Parasitic type of interaction leads to harm of one species while gain of another is a type of positive negative interaction.
Whereas, amensalism is a type of interaction where one species is harmed while others are not affected, it is a type of negative, neutral interaction.

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