How do animals primarily contribute to an ecosystem?

Animals primarily contribute to an ecosystem by serving as food sources for other organisms. In a food web, animals play a crucial role in the transfer of energy from one level to another, supporting a diverse array of life. Herbivores consume plants, and in turn, they become sources of energy for carnivores that prey on them. Additionally, decomposers, which often include certain animal species, break down dead organic matter, recycling nutrients back into the soil, which benefits plants and supports further animal life. This interconnectedness fosters a balanced ecosystem where various species rely on one another for survival.

Other options do not capture the primary role of animals effectively. For instance, while animals may contribute to soil properties, like acidity, it is not their main role in an ecosystem. Similarly, respiration does release carbon dioxide rather than oxygen, and animals, in general, do not create oxygen; that process primarily involves plants through photosynthesis. Additionally, animals do not inherently reduce biodiversity as they often contribute to it by supporting various species within the food web. Thus, their primary contribution lies in their role as vital food sources within the ecosystem.