1. Oxpecker: The oxpecker benefits from the relationship by obtaining a reliable source of food. Hippopotamuses have thick skin that is often covered in parasites, such as ticks and flies. Oxpeckers feed on these parasites, helping to keep the hippopotamus's skin clean and healthy. In return, the hippopotamus provides the oxpecker with protection from predators and a safe place to roost.

2. Hippopotamus: The relationship also benefits the hippopotamus. The oxpecker helps the hippopotamus to groom and maintain clean, parasite-free skin. By eating parasites and insects that may irritate or harm the hippopotamus, the oxpecker assists in keeping it healthy and comfortable. Additionally, the oxpecker's presence helps to deter other insects from landing on the hippopotamus, further reducing the risk of infestation and disease.