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What Is Commensalism In Biology

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Endogenous Infections And Normal Microbial Flora Of The Human Host

Types of Symbiosis (Mutualism, Commensalism, Parasitism)

The distinction between parasitism, commensalism and mutualism is not sharp and the condition of the host and the location of the bacteria may make a big difference. For instance, UPEC are commensals in the colon but cause infections in the urinary tract. Some micro-organisms, referred to as opportunistic pathogens, are commensals in the majority of people but can cause disease in an immunocompromised host. Candida albicans is part of the normal oral flora, but in acquired immunodeficiency syndrome patients with low numbers of CD4+ T cells, C. albicans causes thrush and esophagitis. Similarly, virtually all immunologically normal individuals chronically infected with human cytomegalovirus are asymptomatic, but CMV can cause colitis and pneumonia when the immune system is suppressed. It has been suggested that chronic infection with highly prevalent viruses, including herpesviruses, may play a protective role against bacterial infection by boosting innate immunity, implying a complex, three-way relationship that defies easy classification.27 Thus, the host and its indigenous microflora maintain a delicately balanced relationship that, when disrupted, may lead to the development of infectious disease.

Caitlin S.L. Parello, in, 2020

Commensal Gut Bacteria The Debate

Human beings have what is called a gut microbiota, which is a community of bacteria and microbes that live in our gut and control and modulate certain chemical processes there.

These processes include making Vitamin K, which is produced by certain intestinal bacteria, and increasing metabolic rate which helps reduce the likelihood for obesity and dyslipidemia.

Another very important function of our gut microbiome is to fend off other bacteria, especially pathogenic bacteria, that would like to latch on and cause gastrointestinal infections, with symptoms like nausea, vomiting, and diarrhea. If our natural gut bacteria are present, colonizing our intestines, there is not as much room or opportunity for pathogenic bacteria to take hold.

Some people get sick with stomach bugs after taking antibiotics. This seeming paradox is because the antibiotics killed the good bacteria of their gut microbiome, giving room for pathogenic bacteria to take hold and cause infection.

Yet with all these important activities that our gut bacteria help us to regulate and maintain, there remains a debate as to the actual classification of the gut microbiome. Is our relationship with our gut bacteria an example of commensalism, or is it an example of mutualism?

Roles In Human Health And Disease

A continuum between symbiosis, commensalism, pathobiontisis, and pathogenicity can be used to describe interactions between the microbiome and its host. Symbiotic members of the microbiome are considered beneficial 2 a relationship between two different species in which at least one member benefits without causing detriment to the other is described as symbiosis.4 Microbes referred to as commensals are those that, to our knowledge, neither benefit nor harm the host.2 Specific microscopic organisms that are permanent residents of the microbiome but can cause inflammation and pathology under certain conditions are referred to as pathobionts, whereas pathogenic bacteria cause damage to the host.5,28

Under homeostasis, the various members of the human microbiome are balancedreferred to as symbiosis and contribute to a variety of critical host functions including metabolism , maintenance of mucosal barrier function, development of the immune system , and prevention/inhibition of pathogenic microorganism growth.2933 Microbial imbalance or dysbiosis whether due to reduced microbial diversity or caused by changes in the relative proportions of taxa within a given communityis associated with multiple disease states and can cause major health consequences.1,2

Examples of immunological diseases of the skin and gut that may be associated with the microbiome

K.M. Oliver, J.A. Russell, in, 2016

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What Are 5 Examples Of Commensalism

What are 5 examples of Commensalism?

  • Orchids Growing on Branches. Orchids are a family of flowering plants that grow on trunks and branches of other trees.
  • Sharks and Remora Fish. The remora or suckerfish is a small fish that grows to about three feet.
  • Milkweed and Monarch Butterfly.
  • Burdock Seeds on Animals.

Bromeliads And Other Animals

Commensalism Stock Photos, Pictures &  Royalty

Bromeliads do an effective job of capturing water from their adjacent environment and then storing that water.

This retention capability of excess water ends up attracting a variety of insects and larger animals.

These organisms use the plant as their shelter and depend on the water storage system of the plant. The animals do not affect the plant adversely. So they exhibit a commensal relationship with the plant.

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Difference Between Mutualism Commensalism And Parasitism



In Mutualism, two different species interact and take mutual benefits for a long or short period of time.

In Commensalism, two different species interact with out other and the commensal alone gets benefits without harming the host.

In Parasitism, two different species interact and the parasite receives benefits at the expense of the host.

Mutualism is a positive interaction.

Commensalism is a positive interaction.

Parasitism is a negative interaction.

In mutualism, both organisms need each other.

In commensalism, the commensal needs the host but the host doesn’t need the commensal

In parasitism, the parasites need the host while the host doesn’t need the parasites

Example- Gut bacteria in the guts of mammals.

Example- Orchids growing on trunks and branches of other trees.

Example- Cuscuta and letches.

Examples Of Commensalism In Nature

Commensalism is a pseudo-partnership in which one species extracts benefits from another without causing it harm or benefit. The commensal organism obtains food, shelter, locomotion, or support. Commensalism can either be a brief interaction or a lifelong symbiosis.

This contrasts with mutualism, whereby both species prosper parasitism, in which one species prospers at the cost of another and amensalism, in which one organism is harmed while the other remains no better or worse for the exchange. There are four types of commensalism, depending on the relationship between the organisms.

  • Inquilinism is a relationship where one body depends on the other for permanent housing, such as a bird living in a tree hole.
  • Metabiosis is a relationship where one organism forms a habitat for the other. These include maggots living in dead bodies or hermit crabs using the shells of dead gastropod for protection.
  • Phoresy is commensalism relationship where an organism attaches to the other for transport. Examples are millipedes on birds and pseudoscorpions on mammals.
  • Microbiota organisms that form communities within the host organism. These include bacteria on human skin.

The following are ten intriguing examples of commensalism in the wild.

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Commensalism Mutualism And Parasitism

Symbiosis describes several types of living arrangements between different species of organisms in an ecosystem. These relationships can be beneficial, neutral, or harmful to one or both organisms which are called symbionts. In the complex web of nature, species often have several symbiotic relationship at a time.

Symbiosis can take two forms known as obligatory and facultative. In obligatory symbiosis, one or both organisms are entirely dependent on the relationship and will die without it. Conversely, organisms in facultative relationships can live independently from each other.

Symbiotic relationships are also described by the physical relationship between the symbionts. Conjunctive symbiosis occurs when the symbionts have bodily contact with each other. In contrast, symbionts that do not have physical contact have a disjunctive symbiotic relationship. The term ectosymbiosis is when one organism lives on another, like a flea living in a dogs fur. Endosymbiosis is a relationship where one symbiont lives in the tissues of another such as bacteria living in the human gut.

Commensalism, mutualism, and parasitism are the three main categories of symbiosis found in nature.

Members Of The Commensal Microbiota

Symbiosis: Mutualism, Commensalism, and Parasitism

Among gram-negative anaerobic cocci,Veillonella species are considered mainly harmless, or even beneficial, colonizers of the mouth from the early years of life onward.25Acidaminococcus andMegasphaera species reside the human intestine at young age however, geographic or ethnic differences, or both, in their abundance are significant.26

Among GPAC organisms,R. gnavus plays an important role as an early colonizer of the human gut.27 Although members of the generaAnaerococcus, Finegoldia, Parvimonas, Peptoniphilus, andPeptostreptococcus are commonly present as part of the human microbiota, residing the mouth, intestine, and both the female and male genital tract as well as the surfaces of the eye, nasal cavity, and skin,1,2831 only limited knowledge exists about their role as commensal organisms.

J.P. Veiga, in, 2016

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Commensalism Between Chaffinches And Spotless Starlings

In León, northwestern Spain, starlings feed on blackberries in summer. When they eat they drop seeds to the ground or on the leaves of the mulberry tree. Chaffinches are granivorous animals who will search among the leaves and the ground for the seeds discarded by the starlings. They may even eat them directly from the starlings’ feces.

Commensal Organisms On A Macro Level

Commensalism is thought to have developed between larger species due to certain evolutionary changes and ecological realities. Larger species, such as humans, fed on things and created waste, and then other species may have learned to follow near to humans to consume their waste. This occurred without harming the humans.

In fact, one of the theories of how dogs were tamed and domesticated involves the principles of commensalism. As ancient dogs kept coming closer to humans to consume the leftovers of their meat, humans eventually developed bonds with first individual dogs and then whole communities of dogs. These dogs were naturally less aggressive than some other species of animals, so they took to these bonds with greater ease. Ultimately, social ties were established between dogs and humans, and this became one of the bedrocks of their ultimate domestication.

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Commensalism The Debate: Is It Even Real

Believe it or not, there is still a debate as to whether true commensalism actually exists. Some scientists believe that every symbiotic relationship is either mutualistic or parasitic and, if we think we are seeing commensalism, that is only because we have yet to discover how the host either benefits from or is harmed by the relationship.

This theory could be possible, especially when we take into account some of the weak, transient, or paltry examples of commensalism we have. Perhaps if we study all commensal relationships in depth, we will discover that they are indeed some other kind of symbiosis. However, for now, this theory is not commonly accepted. We believe commensalism exists, and there are several examples of commensalism that we have in nature.

Commensalism Between Flies And Ham Mites


This is a very curious example of phoresis. When ham is being cured in drying sheds, there can sometimes be problems with mites. They infest the ham and invalidate it for sale. The hams hang from the ceiling so the invasion by mites would seem complicated. These small organisms attach themselves to the flies that visit the hams. When they get to a ham, the mites get off the fly. The flies get nothing and don’t even realize they are carrying mites.

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What Does Commensalism Mean

Commensalism is a relationship between two species of organisms, such as plants, animals, and fungus, in which one species benefits while the other is unaffected, as in Scientists have studied the commensalism of fleas that feed on birds feathers.

A well-known example of commensalism is the relationship between the remora, commonly known as a suckerfish, and a shark. The remora uses its suction cuplike head to attach itself to a shark. The remora benefits from the speed, protection, and leftover food from the shark. The shark gets nothing from the remora. It isnt hurt by the remora, but the remora doesnt help the shark in any way.

You can think of commensalism as a +/0 relationship: One species benefits while the other remains the same. This is what sets commensalism apart from the other types of relationships between organisms, such as mutualism, parasitism, and amensalism.

In mutualism, both species benefit from the relationship. For example, a bird might pick food out of the teeth of an alligator, which prevents the teeth from becoming infected. Mutualism is a +/+ relationship because the bird gets food to eat and the alligator gets cleaner teeth.

In parasitism, one species benefits at the expense of the other species, a +/- relationship. For example, when a mosquito bites you, it has drunk some of your blood, which nourishes it. You, however, get an itch bite and possibly a disease carried by mosquitoes, such as Eastern equine encephalitis .

Features Of Commensalism In Relationships

What are some features we see time and again in commensalism and commensal relationships? Just like in parasitism, the organism that benefits tends to be significantly smaller than its host . This makes sense because a very large organism might inevitably bother or harm the host if it was living on or around it. A smaller commensal can be more easily ignored than a bigger one would be.

Commensalism can vary in its timing and intensity, like any other symbiotic relationship. Some commensals have very long-term or even lifelong relationships with their hosts, while others have short-lived, transient relationships. Some commensals may derive extreme benefits from their hosts, while others may have weak, minor benefits.

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Population Interaction In The Ecosystem

In an environment, both biotic and abiotic factors are present which are also known as being the biological and physical factors respectively. CO2, water, temperature, air pressure, wind and osmotic balances are the nutrients that are required for a living being. The population can be very well affected by the interactions of the abiotic factors present in the ecosystem.

Below mentioned are the main modes of interaction between populations

Commensalism Definition In Biology

Symbiotic Relationships-Definition and Examples-Mutualism,Commensalism,Parasitism

Commensalism is a type of symbiotic relationship seen in nature. While the word commensal might remind us of the word community, the actual etymology of the word commensal indicates a more direct meaning in French and Latin. Commensal comes from the joining of two words: com– which means together, and mensa– which means table. Commensal more literally translates to eating at the same table, a beautiful turn of phrase.

In community ecology, however, commensalism is defined as a relationship in which one species benefits and the other does not benefit, but is also not harmed. Commensalism leads to benefits for one organism, and neutrality for the other one.

Symbiosis is a term encompassing the broad range of communal relationships that organisms and different species can have when living on, within, or near each other. If both species benefit, the symbiosis is termed mutualism. When one species benefits, but the other is harmed the symbiosis is termed parasitism. Commensalism is the third type of symbiotic relationship, and that is what we will examine further .

Figure 1: Symbiotic relationships. Expii.

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Other Types Of Symbiosis

Because there are so many different types of organisms, it makes sense that there are many ways they can interact with each other. There are multiple types of symbiosis. The three most commonly studied are commensalism, mutualism, and parasitism, but weve included some additional examples as well to give you a fuller idea of the many ways symbiosis exists in nature. Next to the name of each type of symbiosis are symbols indicating whether the organisms benefit, are harmed, or arent affected by the relationship. The symbol for commensalism is which means one organism benefits and the other isnt affected.

Summary: Commensalism Definition Biology

Need to define commensalism? The simplest commensalism definition is that its a type of symbiosis where one organism benefits and the other neither benefits nor is harmed. The three main types of commensalism are inquilinism, metabiosis, and phoresy.

Although it can be difficult to prove an organism truly isnt impacted by its relationship with another organism, there are numerous commensalism examples in nature. The commensalism relationship is just one type of symbiosis other types include mutualism, parasitism, predation, amensalism, and competition.

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Woodpeckers And Other Animals

Woodpeckers are noted for their special skills in drilling small compact holes in the trees. They use these holes as nests and lay their eggs there during the breeding season.

However, once the babies grow up and leave the nest, the place remains vacant for a while after which other kinds of birds and different other organisms like squirrels make these places their home.

They do not only drill holes for making their nests but often they drill smaller holes in the trees to look for bugs. So even smaller organisms then use these holes as their habitat.

Commensalism Definition And Examples

Examples of Symbiosis

In ecology and biology, commensalism is a type of symbiotic relationship between two species in which one benefits without harming the other. Usually, the host species offers shelter, support, food, or locomotion. The organism receiving the benefit is called the commensal. Commensalism ranges in duration from brief interactions to life-long symbiosis.

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Commensalism Between Opiliones And Ants

In certain areas of Argentina, the climate is very dry. Opiliones, a type of arachnid also known as harvestmen, cannot live in such arid environments. Anthills offer a more humid microclimate that allows opiliones to survive. They live inside the anthills without causing the ants benefit or harm, essentially the definition of commensalism.

Hermit Crabs And Dead Gastropods

Hermit crabs depend on shells for their survival. It is an important defense mechanism that protects them from a variety of predators both on land and in water.

However, they do not naturally contain these shells. They need to acquire them from other sources.

They are majorly found to acquire the dead shells of gastropods and then they start to use these shells as their cover.

So these crabs are dependent upon the gastropod shells for their better survival and this symbiosis doesnt affect the gastropods in any way or other as the hermit crabs only acquire the shells of dead gastropod snails and not of living ones.

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