Differences between Mutualism and Commensalism: Types & Facts

Definition of Mutualism and Commensalism

Interdependent associations refer to the relationships where two organisms belonging to different species rely on one another, usually concerning existence, development, and or reproduction. In the list of these relations, mutualism and commensalism can be considered to be the most significant in the framework of ecological science. The definition of mutualism explains linkings between two organisms, whereby each enjoys improved fitness as a result of cooperation.

However, commensalism refers to situations where one organism benefits, but the other is not influenced by the interaction. Knowledge of these relations can go far in contributing to knowing the processes that take place in ecosystems in terms of species complexity and sustainability. They show how organisms interact or reciprocate with each other in a certain environment affecting factors such as nutrient availability, availability of species and the health of that particular ecosystem. This article underlines the importance of mutual and commensalism relations to understand ecosystems’ dynamics and implement further preservation measures.

Mutualism

This is the kind of symbiotic relationship whereby there is the sharing of benefits between two species of organism. While this interaction is beneficial for the two partners, it increases the fitness, survival, or reproduction rate for both species. While parasitism and commensalism are generally considered non-reciprocal, and one species benefits at the other’s expense or is unfazed by the latter’s existence, mutualism is always reciprocal.

Examples of Mutualism in Nature

Mutualism is pervasive and can be observed across various ecosystems:

Pollination: It is mutualism in which bees benefit by getting their food and at the same time assisting the plant in pollination since the insect has brought pollen to the plant.

Mycorrhizal Associations: Mycorrhizal fungi are microbes that form beneficial associations with plants by penetrating plant root structures and in the process enhancing the plant’s ability to obtain nutrients from the soil in return for carbohydrates derived from plant photosynthesis.

Cleaning Symbiosis: For example, the cleaner fish like cleaner wrasses feed on the remains and feed on the parasites that may be present on the larger fish since they manage to feed on the fish as it is cleaning.

Types of Mutualism

Mutualistic relationships can be categorized based on the nature of the benefits exchanged:

Obligate Mutualism: Individuals of a species interact with other species to obtain food, shelter, or reproductive opportunities, for example, corals and zooxanthellae algae.

Facultative Mutualism: Commercial parties get gains but species are not dependent on each other as with most pollination relations.

Defensive Mutualism: It’s as if ants harbour and defend Acacia trees against herbivores or pathogens.

Trophic Mutualism: Species exchange nutrients or energy in the following forms, for example, nitrogen-fixing bacteria (rhizobia) and leguminous plants.

Also Read

• Practice MCQ on Mutualism
• Practice MCQ on Commensalism
• Organisms and Population
• Population Interaction

Commensalism

Commensalism is one of the types of symbiotic relationships and implies that one of the organisms benefits while the other remains unaffected. As for commensal relationships, one participant receives profit in the form of shelter, food, or transportation, whereas the other participant is not affected at all.

Commensalism is prevalent in various ecosystems:

Epiphytic Plants: Some plants like the orchids and the ferns cling to the existing trees on which they get support and light without harming the trees.

Remoras and Sharks: This is because remoras use their clamp-like mouth that is found at the top of their head and attach themself to sharks, feeding on the leftover scraps of meat that the shark has already chopped, all without negatively affecting the shark.

Birds and Nesting: Usually, birds create their nests in trees, they build their nests on the branches or sometimes in tree hollows and this does not harm the tree because it does not interfere with the tree's ability to live.

Example of Commensalism

Orchids can be found growing on tree branches and trunks. They extract fluids from tree stems but do no assistance to the host. The only source of water for orchids is their hosts. Since they are able to prepare food for themselves, they do not need nutrients from trees.

Types of Commensalism

Commensal relationships can be categorized based on the nature of benefits received:

Inquilinism: One organism occupies the ecological niche of another while the occupied host’s ability to reproduce is not influenced, like the plants that grow on trees.

Phoresy: There is one organism riding on another as in the case of mites on insects or birds.

Microbiota: Symbiotic microorganisms exist on or in the larger organisms and may include the skin bacteria or gut bacteria for the larger organisms without causing them any harm.

Key Differences Between Mutualism and Commensalism

The mutualism and commensalism differences are given below. Check out more Differences and Comparisons Articles in Biology for a better understanding of concepts.

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