What do consumers primarily obtain from other organisms?

Consumers, which include animals and humans, primarily obtain energy from other organisms. This is because consumers are heterotrophs, meaning they cannot produce their own food through photosynthesis like plants do. Instead, they rely on eating other living organisms—plants or animals—to acquire the energy necessary for growth, maintenance, and reproduction.

When consumers eat plants, they obtain energy stored in the form of carbohydrates, fats, and proteins. When they consume other animals, they similarly acquire energy as well as the nutrients those organisms have stored. This relationship is fundamental to ecosystem dynamics, as it establishes food webs and energy flow through different trophic levels.

While nutrients and gases like oxygen and carbon dioxide are also essential for consumers, their primary role is to facilitate energy transfer. Nutrients support metabolic functions and the gas exchange process, but neither can substitute for the energy that consumers derive from their food sources. Therefore, energy is the most critical resource that consumers obtain from other organisms.