What Is Commensalism? Understanding Key Concepts and Examples
Commensalism, in biology, is a relationship between individuals of two species during which one species obtains food or other benefits from the opposite without either harming or benefiting the latter. The commensal, which is regarded as a species, benefits from the association and gets benefits in the form of shelter, support, nutrients or locomotion from the host species which is unaffected.
The commensal relation is usually between a bigger host and a smaller commensal. The host organism is really unchanged by the interaction, whereas the commensal species may show great morphological adaptation. This relationship is often contrasted with mutualism, during which both species benefit.
One of the best-known samples of a commensal is the remora (family Echineidae) that rides attached to sharks and other fishes. Remoras have evolved on the very best of their heads a flat oval sucking disk structure that adheres to the bodies of their hosts. Both remoras and pilots fish prey on the leftovers of their hosts’ meals. Other samples of commensals include bird species, like the good egret (Ardea alba), that prey on insects turned up by grazing mammals or on soil organisms stimulated by ploughing. Various biting lice, fleas, and louse flies are commensals therein they feed harmlessly on the feathers of birds and on sloughed-off flakes of skin from mammals.
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;
Competition
Competition can be defined as the relationship that takes place when two or more species compete for the same resources that are limited. The resources for which they compete might be food, water, light or any prey. Therefore, here the name is justified, i.e Competition. All these factors are very important for the growth and survival of the organisms.
Predation
This is a relationship where one species depends entirely on the opposite for its food and survival. The species which feeds on other species is named predator whereas the one that's fed upon is named the prey. This complete relationship is named Predation.
Predator is typically stronger than the prey, and hence it consumes prey during its entire life cycle. In some food chains and food webs, a predator can also fall prey as all living organisms develop a kind of defence mechanisms after a certain period of time.
The words ‘predator’ and ‘prey’ aren't always limited to animals. They are implied in the connection between animals and plants also. for instance – rabbit feeding on carrots, bear eating berry and grasshopper and leaf.
Camouflage
Camouflage literally means ‘to disguise’. it's the phenomena where an organism or a species develops structural adaptation that helps them to blend with their surroundings is understood as camouflage. This helps them avoid getting detected by predators.
Symbiosis
Symbiosis is a Greek term that means living together. In many relationships, the two or more species or organisms stay dependent on each other for their food and survival for life. This kind of relationship in which one organism lives on another with a mutual but stereotypic behaviour is called symbiosis.
There are three types of Symbiosis:
Mutualism – where both species are benefitted.
Commensalism – where one species benefits without harming the opposite.
Parasitism – when one species is benefitted by harming the other species.
Difference Between Mutualism, Commensalism and Parasitism
FAQs on Commensalism: Meaning, Types, and Biological Importance
1. What is commensalism? Explain with a common example.
Commensalism is a type of ecological interaction between two different species where one species benefits while the other is neither harmed nor helped. This relationship is often denoted as a (+/0) interaction. A classic example is an orchid growing on the branch of a mango tree. The orchid gets a place to grow and better access to sunlight, but the mango tree is largely unaffected by its presence.
2. What are some other classic examples of commensalism found in nature?
Several well-known examples of commensalism showcase this unique relationship:
- Cattle Egrets and Grazing Cattle: The egrets follow cattle and eat the insects that are stirred up from the vegetation as the cattle move. The cattle are unaffected, while the egrets get an easy meal.
- Barnacles on Whales: Barnacles attach themselves to the hard surface of whales. This provides the barnacles with a stable place to live and access to nutrient-rich water, while the whale is not significantly affected.
- Remora Fish and Sharks: Remoras attach to sharks and other large marine animals to get a free ride (phoresy) and feed on the leftover scraps from the host's meals. The shark is not harmed by this interaction.
3. What is the key difference between commensalism and mutualism?
The key difference lies in the outcome for the second species. In commensalism (+/0), only one species benefits, and the other remains neutral or unaffected. In mutualism (+/+), both interacting species derive a benefit from the relationship. For example, while an orchid on a tree is commensalism, the relationship between bees and flowers is mutualism, as bees get nectar and flowers get pollinated.
4. In a commensal relationship, what are the roles of the 'commensal' and the 'host'?
In this type of interaction, the two participants have distinct roles. The commensal is the species that gains a benefit from the relationship, such as food, shelter, support, or transportation. The host is the other species that is not affected by the interaction; it neither gains a benefit nor suffers any harm.
5. How is commensalism different from amensalism?
Commensalism and amensalism are often confused but are distinct interactions. Commensalism is a (+/0) interaction where one species benefits and the other is unaffected. In contrast, amensalism is a (-/0) interaction, where one species is harmed or inhibited, and the other remains unaffected. A common example of amensalism is the secretion of penicillin by the Penicillium fungus, which kills bacteria without the fungus itself being affected.
6. How can you distinguish between commensalism, mutualism, and parasitism?
You can distinguish these three major population interactions based on the outcome for each species involved:
- Commensalism (+/0): One organism benefits, the other is unaffected.
- Mutualism (+/+): Both interacting organisms benefit from the relationship.
- Parasitism (+/-): One organism (the parasite) benefits at the expense of the other (the host), which is harmed.
7. Why is commensalism considered an important ecological interaction?
Commensalism is ecologically important because it plays a significant role in structuring communities and increasing biodiversity. It allows species to survive in environments they otherwise couldn't by using other organisms for transport (phoresy) or housing (inquilinism). This creates complex interdependencies and contributes to the overall stability and functioning of an ecosystem without necessarily causing negative impacts like competition or predation.
8. Can a commensal relationship ever change into a mutualistic or parasitic one?
Yes, ecological relationships are dynamic and can evolve over time. A commensal relationship can shift if the circumstances change. For example, if the commensal species begins to provide a service back to the host, the relationship could become mutualistic. Conversely, if the commensal's population grows to a point where it starts to negatively impact the host's health or resources, the relationship could transition into a parasitic one.
