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Commensalism, in ecology, is a class of relationships between two organisms where one organism benefits from the other without affecting it. This is in contrast with mutualism, in which both organisms benefit from each other, amensalism, where one is harmed while the other is unaffected, and parasitism, where one benefits while the other is harmed. The word "commensalism" is derived from the word "commensal", meaning "eating at the same table" in human social interaction, which in turn comes through French from the Medieval Latin ''commensalis'', meaning "sharing a table", from the prefix ''com-'', meaning "together", and ''mensa'', meaning "table" or "meal". Originally, the term was used to describe the use of waste food by second animals, like the carcass eaters that follow hunting animals, but wait until they have finished their meal. Commensalism, in biology, is a relation between individuals of two species in which one species obtains food or other benefits from the other without either harming or benefiting the latter. The commensal (the species that benefits from the association) may obtain nutrients, shelter, support, or locomotion from the host species, which is substantially unaffected. The commensal relation is often between a larger host and a smaller commensal; the host organism is unmodified, whereas the commensal species may show great structural adaptation consonant with its habits, as in the remoras that ride attached to sharks and other fishes. Both remoras and pilot fishes feed on the leftovers of their hosts’ meals. Numerous birds feed on the insects turned up by grazing mammals, while other birds obtain soil organisms stirred up by the plow. Various biting lice, fleas, and louse flies are commensals in that they feed harmlessly on the feathers of birds and on sloughed-off flakes of skin from mammals Pierre-Joseph van Beneden introduced the term "Commensalism" in 1876.〔van Beneden, Pierre-Joseph (1876). Animal parasites and messmates. London, Henry S. King.〕 == Examples of commensal relationships == Commensalism is harder to demonstrate or explain than parasitism and mutualism, as it is easier to show a single instance in which the host is affected than it is to disprove that possibility. One example is a whale and barnacles. Another is the titan triggerfish (''Balistoides viridescens'') which creates feeding opportunities for smaller fish by moving large rocks too big for them to shift themselves. Yet another example is the remora, which eats leftover food from a whale and "hitches a ride". Another example of a commensal relationship is the relationship between Cacique birds and the wasp ''Polybia rejecta''.However, the best example for this is of a vulture and a lion. Once the lion has finished its meal, the vulture swoops down and finishes off the carcass. The lion is not affected by this while the vulture gets to eat. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「commensalism」の詳細全文を読む スポンサード リンク
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