Difference Between Mutualism and Commensalism


Main Difference

The main difference between the mutualism and commensalism is that mutualism is that Form of the symbiotic relationship between two or more organisms where they all get benefit while commensalism is the type of relationship between two or more organisms, but only one gets benefits, and the other is unharmed.

Mutualism vs. Commensalism

Mutualism is that type of a symbiotic relationship where both species involved get benefit from the relationship. On the other hand, commensalism represents that type of symbiotic relationship where only one organism get benefits while the other does not benefit and not harmed from the relationship. In case of mutualism, both the organisms are interdependent whereas in case of commensalism both the organisms are not dependent to each other. in mutualism individuals have the obligatory type of relationship while in commensalism organisms do not have obligatory kind of relationship. Mutualism is a short term relationship on the other hand commensalism is a type of long term relationship.


Comparison Chart

Mutualism is the type of relationship between two or many individuals in which all the individuals get the benefitIt is the type of relationship between two or many individuals but one receives the advantage, and other is not
Relationship Type
ObligatoryNot obligatory
Survival in Relationship
Each partner needs the other partner for survivalOne partner can survive without the help of another partner
Relationship between bees and flowers
Relationship between human and stomach bacteria
Hermit crabs using dead gastropods for shelter
Millipedes traveling on birds

What is Mutualism?

Mutualism contains a mutually beneficial relationship that involves two or many species that are different. In other words, the species which are involved in this relationship have different needs for their survival. There are different kinds of mutualistic relationships that are based on transport, defense, nutrition, and shelter. The significant aspect of the mutualistic relationships is that they are obligatory. This shows that each or species are dependent on each other. Each organism needs the other to live. This is to create a fine balance in the ecosystem where different organisms depend on each other for their survival. These are the following types of mutualistic relationships depending on different factors:

  • Nutrition Mutualism: The relationship between the flower and bee is based on nutritional needs. Bees feed on the flower nectar that is produced by flowers while they also act as pollination agents to the flowers. Both species benefit in this mutual relationship.
  • Shelter Mutualism: Human beings need bacteria in their digestive system while on the other side, they provide shelter to bacteria. Thus, the digestive process in human beings is mutually beneficial to both hosts and bacteria.
  • Defense Mutualism: Ants, provide a defense to the acacia plants against browsers while the ants get food from these host plants. Both organisms get benefit from this form of symbiotic relationship.
  • Transport Mutualism: Bees carry the pollen from one flower to the other, and this process facilitates cross-pollination.


Relationship between bees and flowers and humans and digestive bacteria.

What is Commensalism?

Commensalism is a kind of relationship in which two or more organisms coexist, but only one organism get benefit from this association. The other partner that does not benefit is not harmed by this kind of relationship. In commensalism, the other part benefits in the form of obtaining nutrients, shelter, support as well as transport. In this partnership, it can be seen that the host organism that provides shelter or transport to other organisms is not harmed. This type of relationship is divided into the following categories:

  • Inquilinism: One organism gets shelter from the host organism, but that organism does not harm it. Like trees provide permanent shelter to epiphytic plants which grow on them, but there is no harm caused on the host organisms.
  • Metabiosis: The host organism provides habitat to the other organism, but there is no harm caused to the host organism. Hermit crabs, for instance, can use dead gastropods as their habitat and no harm is caused to the host organism.
  • Phoresy: The host organism gives transport to the other organism, but there is no harm caused on the partner carrying the other. Birds, for example, provide transport to millipedes but they are not harmed in the process.
  • Microbiota: Other organisms form communities with the host partner. For example, pilot fishes ride on a shark to obtain food, but they do not harm the host organism.


Hermit crabs using dead gastropods for shelter and millipedes traveling on birds.

Key Differences

  1. In mutualism both the organisms get benefit while in commensalism one organism get benefit while others neither get benefit nor harm.
  2. Mutualism is an obligatory relationship whereas commensalism is not an obligatory relationship.
  3. In mutualism one organism depends on another organism for their survival on the other hand in commensalism one organism is not dependent on another organism for their survival.


Conclusion of this article is that mutualism and commensalism are both types of symbiotic relationships. In mutualism two or many organisms are involved who are dependent on each other for their survival, and both the organisms get the benefit but on the other side in commensalism two or many organisms which participate are not dependent on each other for their survival, and only one organism get the benefit, and other partner does not harm.

Janet White

Janet White is a writer and blogger for Difference Wiki since 2015. She has a master's degree in science and medical journalism from Boston University. Apart from work, she enjoys exercising, reading, and spending time with her friends and family. Connect with her on Twitter @Janet__White