Commensalism:

The relationship between two organisms in which one organism is benefitted and the other is neither benefitted nor harmed is Commensalic relationship. One of the organisms is symbiotic which is referred as commensal and the other is benefitted in neither way.

Commensal:

It is a Latin word in which Com meaning togetherness and mensa meaning table. Commensal meaning English is sharing of food in ecological environment. It is a unidirectional beneficiation process. Commensal usually utilize the host for its shelter either inside the organism or outside the organism. There is no metabolic responsibility sharing between two organisms. When they are estranged, both can survive independently without any external growth factor inclusion.

Types of Association:

Based on the benefit of organisms commensal relationship is classified in to three basic types which are as follows.

• Mutualism is a relationship where two organisms benefit mutually from each other
• Competition is a relationship where two organisms are equally affected or harmed.
• Parasitism is a relationship where one organism is benefitted and the other is affected.

 Types of Commensalism

Based on the duration of interaction, commensalism is classified in to following three types.

• Phoresy
• Inquilinism
• Metabiosis

Phoresy: This relationship is only for transportation purpose. It can be compulsive action or facultative. For instance millipedes on birds, mites on insects, beetles, bees or files and pseudoscorpions on human beings are Phoresy types.

Inquilinism: This relationship is just for shelter. For instance epiphytic plants growing in the trees and birds nesting in the holes of tree are Inquilinism type. Epiphytic plants utilize the nutrients and light required for it to grow from the host trees. The tree is not affected unless epiphytic plant growth is in control. Barnacles are crustaceans that attach themselves to a substrate. The substrate should be hard like rocks, shells, whales and anywhere where they can land their foot without obstruction. For instance they may attach to the shell of scallop, where barnacles benefits by getting shelter from scallop. Scallop is left unaffected by this relationship.

Metabiosis: Second organism utilize first organism after death of first organism. It is indirect dependency nature of organisms like maggots and hermit crabs.

Instance of commensalism:

Commensalism is the utilization of waste of one organism as substrate for other organism. In nitrification process Nitrosomonas oxidize ammonium ion to nitrite and nitrobacter oxidize nitrite to nitrate. Nitrobacter utilize the energy provided by the nitrosomonas oxidation process.

Cattle ergets, native of America is found prevalent in cattle fields. When cattle and other animals graze on the field their movements result in stir up of insects. Cattle ergets finds its food by this way. Cattle form commensal relationship with cattle ergets as it helps cattle ergets to find its food. When army ant moves on the floor, it causes the insects to fly. It ultimately helps birds to catch the insects. Here in this relationship birds are benefitted out of ants and ants remain unaffected.

When there is a change in environment conditions it may seduce commensal relationship. Non pathogenic organism like E. Coli is found in the intestine of human that is in colon. It can also grow outside the human beings. This is commensal due to environment conditions change. Bacteriodes which are obligate can grow in the colon when facultative anaerobic bacteria utilize the oxygen. Here facultative anaerobic bacteria is benefitted by the relationship they have with E. Coli and host, whereas E. Coli is left unaffected by the anaerobic organism.

Other Commensalism relational due to environmental modifications are as follows. Acid tolerant microorganism growth is increased during the fermentation process because of acid waste product formation.  The growth of microorganism over the biofilm helps in the growth of some other microorganism. They may form a colony by firmly attaching to the other organism that is microbially modified. Commensalism between human body and surface of animals and plants surface is vital. Microorganisms that are found over the animals utilize the organic compounds and nutrients on the surface by the animals. Apart from body odor formation they never damage the animals. When the microorganism damages the skin of animals under any stress, then this commensal relationship flanked by microorganism and host shall be pathogenic.