What defines commensalism?

Commensalism is a type of symbiotic relationship characterized by one organism benefiting while the other organism is neither helped nor harmed. In this interaction, the benefiting organism typically derives resources or some form of advantage, such as shelter or transportation, from its partner without affecting the latter's wellbeing.

An example of commensalism is the relationship between barnacles and whales. Barnacles attach to the skin of whales, gaining a mobile environment that provides access to nutrient-rich waters as the whale swims, while the whale remains largely unaffected by the presence of the barnacles.

This definition is essential because it distinguishes commensalism from other types of symbiotic relationships, such as mutualism, where both organisms benefit, and parasitism, where one organism benefits at the expense of the other. Understanding these distinctions helps clarify the dynamics of ecological interactions and their impact on species coexistence and ecosystem functioning.