Understanding what Autotrophs and Heterotrophs are

Living organisms obtain their energy in varied ways. Some organisms, including animals, fungi and bacteria capture their energy by feeding on the organic substances produced by other living organisms; such organisms are known as heterotrophs. Other organisms obtain their energy from inorganic molecules. These organisms are classified into two distinct groups; autotrophs and chemoautotrophs. Autotrophs are those organisms that produce organic substances through photosynthesis using sunlight as a source of energy and chemoautotrophs are those organisms that capture energy from inorganic chemicals to produce the organic substances they need.

Autotrophic organisms include plants, algae and many types of bacteria on which most living things on Earth depend. Autotrophs generally utilize the energy from the Sun, water and carbon dioxide (CO2), in a process known as photosynthesis, to manufacture all the organic compounds they need for metabolism. On their energy producing process, these organisms release oxygen into the Earth’s atmosphere. Heterotrophs, on the other part, cannot capture carbon; therefore, they use organic carbon from other organisms for growth. The organic compounds produced by autotrophs, such as carbohydrates, proteins and fats, are often used as an energy source contained in food by heterotrophs.

All living organisms on the planet require energy for survival. Some organisms, including plants, algae and some bacteria, obtain their energy from sunlight to produce organic substances in a process known as photosynthesis. They’re called autotrophs because they are able to produce their own energy. Heterotrophs rely on autotrophs for their energy needs. They obtain their energy by ingesting the organic products of autotrophs, such as carbohydrates, proteins and fats. Heterotrophs may not only consume autotrophs to capture energy, but they also may feed on other heterotrophs.

Difference between autotrophs and heterotrophs

While both autotrophs and heterotrophs require the energy from the Sun and water to live, autotrophs differ from heterotrophs in their ability to utilize the energy from the sun to drive the internal processes that produce organic compounds. Autotrophs possess a green pigment known as chlorophyll, which is responsible for the capture of sunlight in plants. Heterotrophs lack this organelle, thus, they cannot utilize the Sun’s energy and must rely on the complex organic products produced by autotrophic organisms. Autotrophs are the basis of most food chains. Chemoautotrophs are organisms that synthesize organic compounds from the oxidation of inorganic chemicals as a source of energy, rather than from the utilization of sunlight as in photosynthesis.


Most habitats in the world depend on autotrophs as primary producers. Autotrophs capture the energy from sunlight and utilize it to manufacture rich-energy molecules that they use it to drive their internal processes. Plants either on land or in the ocean (algae) are at the base of the food chain. The energy produced by plants is moved along the food chain when an organism eats another, thus, the primary consumer (herbivores) eats the primary producers (plants and algae), the secondary consumers (carnivores) eat the primary consumers, and the tertiary consumers (omnivores) eat the secondary consumers and so on. Saprobes (fungi) are organisms that feed on the decaying matter of other organisms.


Since heterotrophs cannot produce their own energy, they must consume other organisms. Heterotrophs obtain their energy by consuming autotrophic organisms, including plants, algae and bacteria. Heterotrophs are consumers in food chains. They consume autotrophs and heterotrophs. Depending on their eating habits, heterotrophs may be grouped into herbivores, carnivores, omnivores and saprobes. Predatory animals are those that feed on other animals. Saprobes (fungi) are those organisms that feed on the decaying particles of organisms. Some organisms, including bacteria, obtain their energy by forming mutualistic, parasitism, commensalism associations, with other living organisms.

Autotrophs are at the very base of the food chains in every ecosystem of the world. The energy they store in the form of carbohydrates, proteins and fat is consumed by heterotrophs, which are the organisms on the second level of the food chain. Heterotrophs must convert the organic molecules produced by autotrophs, usually contained in the food they eat, into energy. The balance between autotrophs and heterotrophs is crucial in the ecosystems of the world. According to learner.org, the exchange of energy along living organisms begins with the capture of sunlight by plants. This energy is transferred to consumers in a food chain in small amounts.