Difference between Mutualism and Commensalism

Determining the difference between mutualism and commensalism requires us to begin by outlining the process that leads to the occurrence or interconnectedness of these two biological concepts.

As a point of departure, it should be clearly stated that the ecosystem is comprised of various species and these tend to interact with each other in different ways for their survival. This link is commonly known as symbiotic relationship which reflects the connectedness of the species in their survival within the ecosystem. Thus, mutualism and commensalism represent two major notable symbiotic relationships linked by some form of feeding mechanism. Apart from this, symbiotic relationships also offer defense mechanisms as well as shelter for other species. In some cases, the interaction between different species may have negative, neutral or positive impacts on each other.

Mutualism represents a symbiotic relationship where both species involved benefit from the relationship. On the other hand, commensalism represents a symbiotic relationship where only one organism benefits while the other does not benefit from the relationship. One notable aspect is that the organism that does not benefit is not harmed by the nature of relationship between the two.

Therefore, the major difference between mutualism and commensalism is that both organisms benefit in mutualism while only one organism benefits in commensalism but the other one is not affected.

• Mutualism-both species involved benefit from the relationship. In other words, the relationship is mutually beneficial to both organisms as the name implies. The relationship that exists is obligatory implying that each organism requires the other for survival in the ecosystem.
• Commensalism- only one organism benefits from the symbiotic relationship that exists between the species involved. The other organism that does not benefit remains neutral and is not harmed.

Key features of Mutualism

Mutualism involves a mutually beneficial relationship that involves two species that are different in nature. In other words, the species involved have different requirements for their survival. Notably, there are different types of mutualistic relationships that are based on nutrition, shelter, defense and transport. These are illustrated in the examples below:

• Nutrition mutualism- the relationship between the bee and flower is based on nutritional needs. Bees feed on the 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 require bacteria in their digestive system while on the other hand they provide shelter to bacteria. Thus, the digestive mechanism in human beings is mutually beneficial to both hosts and the bacteria.
• Defense mutualism- ants provide defense to the acacia plants against browsers while at the same time the ants obtain food from these host plants. Both organisms 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. This encourages flowering and ultimately growth of other species that are required in the ecosystem.

The major notable aspect about the mutualistic relationships outlined above is that they are obligatory. This implies that they are dependent on each other. Each organism requires the other for their survival. This is meant to create a fine balance in the ecosystem where different organisms can depend on each other for their survival.

Key features of Commensalism

Commensalism represents a kind of relationship where two or more organisms coexist only one organism will benefit from the association. Interestingly, the other part that does not benefit is not harmed by this kind of relationship and it is referred to as the host organism. Essentially, in a commensalistic relationship the other part benefits in form of obtaining nutrients, shelter, support as well as transport. Precisely, this form of relationship is divided into the following categories. inquilinism, metabiosis, phoresy, and microbiota.

• Inquilinism- in this kind of relationship, one organism seeks shelter from the host organism but it does not harm it. For example, trees provide permanent shelter to epiphytic plants which grow on them but there is no harm caused on the host organisms.
• Metabiosis- in this form of commensalistic relationship, the host organism provides habitat to the other partner 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- in this relationship, the host organism provides 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 in order to obtain food but they do not harm the host organism.

Essentially, commensalism is a relationship that involves two or more organisms but only one of them benefit from that kind of association. In this partnership, it can be observed that the host organism that provides shelter or transport to other organisms is not harmed.

Table showing the difference between mutualism and commensalism

Summary of the differences between mutualism and commensalism

Meaning

• Mutualism– involves a symbiotic relationship between two or more organisms and it is mutually beneficial. The organisms involved are dependent on each other for their survival. This relationship promotes the life of the other.
• Commensalism- in contrast, this commensalism involves a symbiotic relationship that benefits only one organism but the other one is unharmed. The host organism can survive on its own since it does not require any form of support from the other species.

Occurrence

• Mutualism- depending on the nature of organisms involved, contact between them can be short term based like the example of bees and flowers. It can also be long term such as the digestive system of human beings and bacteria.
• Commensalism- this symbiotic relationship can be continuous as illustrated by the example of trees that provide permanent shelter to epiphytic plants which grow on them. When the epiphytic plants are not removed they will permanently stay on the trees as their host organisms.

Nature of relationship

• Mutualism- the relationship between two or more partners involved is obligatory. Each partner needs the existence of the other organism in the relationship for survival. In other words, the relationship is mutually inclusive implying that these organisms are dependent on each other for their survival.
• Commensalism- the relationship between two or more organisms involved is not obligatory. This means that the other organism in the relationship can survive without the other.

Examples

• Mutualism- the association between flowers and bees illustrates a mutually beneficial relationship. Bees require flowers for food while flowers also require bees to facilitate pollination, a process that is crucial in plant growth and development. The relationship between bacteria and human digestive system is another good example that is beneficial to both species.
• Commensalism- a good example involves millepedes travelling on birds or hermit crabs seeking shelter from dead gastropods. Host organisms do not benefit in the association formed.

Conclusion

In conclusion, it can be observed that both mutualism and commensalism constitute symbiotic relationships among different living organisms in the ecosystem but these relationships significantly differ in many ways. These relationships are mainly influenced by the need to obtain food, transport, shelter as well as other forms of support like shelter. Essentially, the main difference between these two symbiotic relationships pertains to the aspect benefits likely to be obtained from them. As noted, both organisms in mutualistic relationship benefit from the association that exists between them. However, in commensalistic relationship, only one organism benefits from the association. Notably, the organism that does not benefit is not harmed by the association. In commensalism, the relationship is likely to be long term while in mutualism it can be short term.

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