Mutualism vs Commensalism
Plants and other organisms may form symbiotic associations, which are considered as non photosynthetic modes of nutrition in plants. Symbiotic associations are associations between two or more species that live together. There are 3 types of symbiotic associations. Those are mutualism, commensalism and parasitism. Commensalism and mutualism are discussed later. Parasitism is an association where only one party is benefitted and it is called the parasite. The other organism on or within which the parasite live is the host. Parasite harms the host by damaging the host tissues and ultimately causing disease or death of the host. Parasitism can be semi parasitism or total parasitism. Semi parasitism is where the parasite obtain water and mineral from the host called haustoria. Loranthus is a good example for semi parasitism. Total parasitism is shown by the parasites which get organic food and mineral nutrients from the host plant. Cuscuta is a good example of total parasitism. Semi parasites are green in colour and are photosynthetic. But total parasites are not photosynthetic.
What is Commensalism?
Commensalism is a relationship where only one party is benefitted, but no harm done to the other party. Orchids growing as epiphytes can be considered as an example. They grow on tall trees to get sun light and mineral nutrients from the barks of the host trees. One of the very good examples is Dendrobium.
What is Mutualism?
Mutualism is a symbiotic relationship where both parties benefit from each other. There are a lot of examples for mutualism. One such mutual association is the micorrhizal association (association between roots of higher plants and a fungus). The organisms involved are higher plants and fungi. The fungus helps the plant to absorb water and minerals. The fungus obtains nutrients/ organic food from the higher plant. In root nodules, the association is between the legume plants and Rhizobium bacteria. The legume plant obtains fixed nitrogen and the bacteria obtain organic food from the legume plant. In coralloid root, the mutual association is between the root of Cycas and Anabaena which is a cyanobacterium. The plant obtains fixed nitrogen due to the presence of Anabaena and the cyanobacterium obtains protection and nutrients from the plant. Another mutual relationship exists between Azolla leaf and Anabaena. Similar to the previous case the plant obtains fixed nitrogen due to the presence of cyanobacterium and the cyanobacterium obtains protection and shelter from the plant. Another popular mutual relationship is lichen. But here no plants are involved. The association is between green algae and fungus. The algae are protected from desiccation and fungus obtains organic food due to the presence of green algae.
What is the difference between Mutualism and Commensalism?
• Mutualism is a symbiotic relationship where both parties benefit from each other whereas commensalism is a relationship where only one party is benefitted, but no harm done to the other party.