In which ecological relationship does one species eat another?

The ecological relationship where one species eats another is known as predation. In this relationship, the predator benefits by gaining nutrition and energy from the prey, which is the organism being eaten. This interaction is crucial for maintaining ecological balance, as it helps to regulate population sizes within ecosystems. Predation also influences the evolution of both predators and prey, leading to adaptations such as enhanced hunting skills in predators and defensive mechanisms in prey species.

In contrast, commensalism describes a relationship where one species benefits while the other is neither helped nor harmed. Mutualism involves a relationship where both species gain benefits from their interaction. Parasitism, while similar to predation in that one organism derives benefit at the expense of another, typically involves the parasite living on or in the host and may not result in the immediate death of the host, which distinguishes it from predation. Thus, predation is specifically characterized by the act of one species preying upon another.