Which ecological relationship is characterized by one organism benefiting while the other is unaffected?

The ecological relationship characterized by one organism benefiting while the other is unaffected is known as commensalism. In this type of interaction, one species gains benefits such as food, shelter, or transportation, while the other species neither benefits nor is harmed. An example of commensalism is barnacles attaching to the shell of a turtle; the barnacles gain a place to live and access to water currents, while the turtle is usually not affected by their presence.

In contrast, mutualism involves interactions where both species benefit from the relationship. Parasitism is different, as it involves one organism benefiting at the expense of another, which is harmed in the process. Symbiosis refers to any interaction between two different organisms, which can include mutualism, commensalism, and parasitism but is not specific to just one type of relationship.