Difference Between Commensalism and Mutualism

In the natural world, no organism exists in absolute isolation. The first law of ecology states, ” everything is connected with everything”. There is a continuous interaction between and among the biotic organisms and their interaction with abiotic interaction. This is Nature.

We can observe various forms of responses of interactions when two species interact with each other. Either of them may have positive, negative, or neutral reactions.

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  • Commensalism is a class of relationships between two organisms where one organism benefits without affecting the other
  • Only one species benefitted.
  • Types:
  1. Chemical commensalism: one species of bacteria feeding on the chemicals produced or the waste products that are not used by the other bacteria
  2. Inquilinism: one species using the body or a body cavity of another organism as a platform or a living space (sometimes food) while the host organism neither benefits nor is harmed. ( birds that live in holes in trees)
  3. Metabiosis: one species unintentionally creates habitat features for another species through one of its normal life activities. ( Hermit crabs lives in snail shell for protection)
  4. Phoresy: one organism attaches to another organism specifically for the purpose of gaining transportation. (mites on bees)
  • No contribution to the evolution.


  • Relationship between two organisms (of different species), that work together to help benefit one another.
  • Both species are benefitted
  • Types:
  1. Trophic mutualisms (resource-to-resource mutualism): Both species receive a benefit from resources. eg- Mycorrhizae(fungi, that improves nutrient and water uptake as well as resist pathogen attack-trees provides support and carbohydrate to the fungi )
  2. Defensive mutualisms (service-to-service mutualism): Both species provide service to each other. eg- The acacia tree provides shelter (in thorns) to the ants while ants protect the tree from herbivores by stinging them.
  3. Dispersive mutualisms(resource-to-service mutualism): one species receive food in exchange for the service provided to it. eg- The birds consume fruits and help to transport the seed for germination.
  4. Obligate mutualisms (symbiosis mutualism): Species are interdependent with one another in a way that one cannot survive without the other. eg- The ant larvae eat only one kind of fungi, and fungi cannot survive without the decay of that leaf.
  • It drives the evolution of much of the biological diversity


Hi, Im chetana khadka from Bardiya. Having always been in close proximity to Nature I have so much enthusiasm to learn and explore my career in Forestry. As a Forestry undergraduate, I realized that even a tiny creature in nature has immense importance in the ecosystem. Really everything is connected to everything and there's nothing like waste in nature. So value yourself, you are also a immense part of nature and leave your conservation footprint before you vanish in it.

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