The term Congo Basin Denizen can be summarized as a HIPPO, which is a five letter word. Hippos are large mammals that live in sub-Saharan Africa and are native to the Congo Basin. They are semi-aquatic animals and spend most of their time in rivers and lakes. Hippos are herbivores and feed on grasses and aquatic plants. They are considered to be one of the most dangerous animals in Africa due to their aggressive nature.