[kuh-men-suh
l] 
| 1. | eating together at the same table. |
| 2. | (of an animal, plant, fungus, etc.) living with, on, or in another, without injury to either. |
| 3. | Sociology. (of a person or group) not competing while residing in or occupying the same area as another individual or group having independent or different values or customs. |
| 4. | a companion at table. |
| 5. | a commensal organism. |
| com·men·sal·ism (kə-měn'sə-lĭz'əm) n. A symbiotic relationship between two organisms of different species in which one derives some benefit while the other is unaffected. |
commensal com·men·sal (kə-měn'səl)
adj.
Of, relating to, or characterized by a symbiotic relationship in which one species is benefited while the other is unaffected. n.
An organism participating in a symbiotic relationship in which one species derives some benefit while the other is unaffected.
commensalism com·men·sal·ism (kə-měn'sə-lĭz'əm)
n.
A symbiotic relationship in which one organism derives benefit and the other is unharmed.
commensalism
in biology, 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. (This kind of relation can be contrasted with mutualism, in which both species benefit.) 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. A commensal relation based on shelter is seen in clown fishes (Amphiprion percula), which live unharmed among the stinging tentacles of sea anemones, where they are protected from predators. 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.
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