What is commensalism?

Commensalism is defined as a type of symbiotic relationship in which one organism benefits while the other remains unaffected. This interaction exemplifies how different species can coexist and interact in an ecosystem without causing harm to each other, which is a key aspect of ecological relationships.

For instance, consider barnacles that attach themselves to the shell of a turtle. The barnacles gain a place to live and access to nutrient-rich waters as the turtle moves, while the turtle continues its life without any noticeable impact from the presence of the barnacles. This illustrates the essence of commensalism: the barnacle benefits while the turtle does not experience any significant gain or loss.

In contrast, relationships where both species benefit represent mutualism, while those in which one species suffers signify parasitism. Competition refers to a struggle between species for limited resources and does not fit the definition of commensalism, since it involves direct negative impacts on one or both organisms involved.