What is an example of commensalism in an ecosystem, and how does it demonstrate the relationship between two species?

An example of commensalism in an ecosystem is the relationship between a remora fish and a shark. The remora fish attaches itself to the shark's body and benefits by getting a free ride and access to food scraps left by the shark. The shark is not affected by the presence of the remora fish. This demonstrates a one-sided relationship where one species benefits (the remora fish) while the other is neither harmed nor helped (the shark).