Commensalism
interaction between two organisms living together in more or less intimate association in a relationship in which one benefits and the other is unaffected.
Commensalism is a long-term biological interaction (symbiosis) in which members of one species gain benefits while those of the other species neither benefit nor are harmed. 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 is harmed and the other benefits.
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 consistent with its habits, as in the remoras that ride attached to sharks and other fishes. Remoras feed on their hosts' fecal matter, while pilot fish feed on the leftovers of their hosts' meals. Numerous birds perch on bodies of large mammal herbivores or feed on the insects turned up by grazing mammals.
Etymology
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". Commensality, at the Universities of Oxford and Cambridge, refers to professors eating at the same table as students (as they live in the same "college").
The Belgian zoologist and paleontologist Pierre-Joseph van Beneden introduced the term "commensalism" in 1876.
Examples of commensal relationships
The commensal pathway was traversed by animals that fed on refuse around human habitats or by animals that preyed on other animals drawn to human camps.
The public source identifies “Commensalism” as interaction between two organisms living together in more or less intimate association in a relationship in which one benefits and the other is unaffected. This brief keeps that definition visible, then builds a research path around Commensalism, interaction and between.
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Contemporary correspondence, administrative files and participant testimony can test how later narratives organized the event or institution. The source revision retrieved here is dated Aug 31, 2026. The linked authority identifier is Q191934. The Library of Congress control number is sh85028900. 1 of 1 selected statements include explicit references; 1 carry qualifiers and 0 use preferred rank. The first chronological checks are 1876.
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This entry incorporates text from “Commensalism” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.