Question

In commensalism
A. Both partners are benefited.
B. Both partners are harmed.
C. Weaker is benefitted while stronger is unharmed.
D. None of the above

Answer 1

Hint: Commensalism is a symbiotic relationship where one species typically uses the opposite for a purpose apart from food.

Complete answer:
Commensalism could be a relationship between individuals of two species within which one species obtains food or other benefits from the opposite.

In commensal interactions, one species benefits while the other is unaffected. The commensal organism may rely upon its host for food, shelter, support, transport, or a mix of those. The commensal—the species that benefits from the association—may obtain nutrients, shelter, support, or locomotion from the host species, which is unaffected. The commensal relation is commonly between a bigger host and a smaller commensal. The host organism is actually unchanged by the interaction, whereas the commensal species may show great morphological adaptation. These relationships are often contrasted with mutualism, within which both species benefit.

One of the best-known examples of a commensal is the remora (family Echeneidae) that rides attached to sharks and other fishes. Remoras have evolved on the highest of their heads a flat oval sucking disk structure that adheres to the bodies of their hosts. Both remoras and pilot fishes take advantage of the leftovers of their hosts’ meals.

Terms associated with commensalism: Commensalism is commonly confused with related words:
- Mutualism - Mutualism is a relationship within which two organisms have the benefit of one another.
- Amensalism - A relationship during which one organism is harmed while the opposite isn't affected.
- Parasitism - A relationship during which one organism benefits and also the other is harmed.
There's often debate about whether a specific relationship is an example of commensalism or another form of interaction. As an example, some scientists consider the link between people and gut bacteria to be an example of commensalism, while others believe it's mutualistic because humans may gain the benefit of the connection.
Many other forms of interaction, however, range from antagonism to commensalism to mutualism, counting on the ecological circumstances. As an example, plant-feeding insects may have large detrimental effects on plant survival or reproduction if they attack small or non vigorous plants but may have little or no effect on large or vigorous plants of the identical species. Some human diseases may cause only temporary discomfort or be life-threatening, betting on the age and soundness of the person.

Types of commensalism:
- Inquilinism - In inquilinism, one organism uses another for permanent housing. An example may be a bird that lives in a very tree hole. Sometimes epiphytic plants growing on trees are considered iniquilism, while others might consider this to be a parasitic relationship because the epiphyte might weaken the tree or take nutrients that will otherwise move to the host.
- Metabiosis - Metabiosis may be a commensalistic relationship within which one organism forms a habitat for one more. An example may be a decapod, which uses a shell from a dead gastropod for defense.
- Phoresy - In phoresy, one animal attaches to a different form of transport. This kind of commensalism is most frequently seen in arthropods, like mites living on insects. Other examples include anemone attachment to decapod shells, pseudoscorpions living on mammals, and millipedes traveling on birds. Phoresy could also be either obligate or facultative.
- Microbiota - Microbiota are commensal organisms that form communities within a bunch of organisms. An example is that the bacterial flora found on human skin. Scientists disagree on whether microbiota are actually a kind of commensalism.

Thus, the correct answer is option (C), weaker is benefitted while stronger is unharmed.

Note: Domesticated animals and commensalism: Domestic dogs, cats, and other animals appear to own started off with commensal relationships with humans. DNA evidence indicates dogs associated themselves with people before humans switched from hunting-gathering to agriculture. It's believed the ancestors of dogs followed hunters to eat remains of carcasses. Over time, the connection became mutualistic, where humans also benefited from the connection, gaining defense from other predators and assistance tracking and killing prey.