What describes commensalism in ecological terms?

Commensalism is an ecological relationship where one species benefits from the interaction while the other is neither helped nor harmed. This means that in a commensalistic relationship, one organism derives some advantage—such as food, shelter, or transportation—while the other species remains unaffected.

For instance, a classic example of commensalism can be seen in barnacles attaching themselves to the shell of a tortoise. The barnacles gain a place to live and access to food as the tortoise moves through the water, while the tortoise remains indifferent to the presence of the barnacles. This distinction highlights the key characteristic of commensalism: the benign impact on the host organism involved in the relationship.

The other options describe different ecological interactions: mutualism involves both species benefiting, parasitism implies one organism benefits at the expense of another, and predation describes a relationship where one organism consumes another. Understanding these distinctions is fundamental in ecology and helps clarify the dynamics of species interactions within ecosystems.