Autotroph Vs Heterotroph- Definition, 14 Differences, Examples

Autotroph Vs Heterotroph Overview

Autotroph Definition

An organism group that can produce its own sustenance using elements such as water, sunshine, air, and other compounds is known as an autotroph.

  • The terms “auto” and “troph,” which imply food and self-respectively, make up the word “autotroph.”
  • Thus, autotrophs are able to produce their own nourishment on their own, without the aid of others.
  • As the foundation of ecological food chains and the source of all other food for all other animals, autotrophs are also known as “producers.”
  • These creatures are crucial because they provide all other living forms with food and energy, either directly or indirectly.
  • In addition to the well-known plants, there are various different species of autotrophs in the environment, like bacteria, algae, and phytoplankton.
  • The majority of autotrophs convert solar energy into chemical energy by photosynthesis. Certain autotrophs also employ phototrophy and chemotrophy.
  • Chlorophyll serves as the photosynthetic pigment for photosynthesis in all living things that are green. Some bacteria, algae, and phytoplankton additionally include additional pigments such as bacterial rhodopsin and carotenoids for photosynthesis.
  • Certain uncommon autotrophs produce food by using the mechanism of chemosynthesis, which gets its energy from chemical processes rather than sunlight.
  • The hazardous chemicals required for the reactions are found in the harsh habitats where the organisms that undertake chemosynthesis reside. Sulfur is used by bacteria found in volcanoes to make their food.
  • Autotrophs comprise the initial trophic level in the food chain. The second trophic level, herbivores, then devours these species, etc.
  • The number of consumers gradually rises as the number of autotrophs does. All other trophic levels get starved as the number of autotrophs declines.

Heterotroph Definition

A category of creatures known as heterotrophs are unable to produce their own food and must instead get it from other species.

The terms “hetero” and “troph”—which both refer to food—combine to form the phrase “heterotroph.”

Because they eat food that autotrophs have produced, heterotrophs are often referred to as consumers. In the food chain, these species create higher trophic levels.

Based on the source of their energy, heterotrophs are further split into two categories. Photoheterotrophs rely on producers for their carbon supply, but they get their energy from light.

In turn, chemoheterotrophs get their carbon and energy from other producers.

Some heterotrophs, including herbivores, are directly dependent on autotrophs for nourishment. Some heterotrophs are indirectly dependent on producers, since they consume the first class of heterotrophs.

The majority of heterotrophs rely on photosynthesis in a variety of different ways. In addition to giving heterotrophs energy and food, photosynthesis also gives them oxygen.

Heterotrophs utilise the reduced carbon molecules produced by autotrophs for their own development and reproduction.

Saprotrophic, parasitic, and holozoic nutrition are the further divisions of heterotrophic nutrition.

Heterotrophic organisms known as saprotrophs ingest dead and decaying organic matter as a source of energy, carbon, and nutrients.

Another kind of heterotroph is holozoic creatures, which eat other species’ solid food and break it down into tiny pieces before distributing it throughout their bodies.

Heterotrophs, known as parasites, are totally reliant on other living things for all of their nutritional needs. The parasite gains in this relationship while the host loses out.

Key Differences (Autotroph vs Heterotroph)

Basis for Comparison Autotroph Heterotroph
Definition An autotroph is a group of organisms capable of producing their own food by utilizing various substances like water, sunlight, air, and other chemicals. A heterotroph is a group of organisms that obtain their food from other organisms and are not capable of producing their own food.
Source of energy The source of energy in autotrophs is either sunlight or chemical reactions. Autotrophs are the direct or indirect source of energy in heterotrophs.
Dependency Autotrophs are independent and can produce their own food. Heterotrophs are directly or indirectly dependent on autotrophs.
Trophic level Autotrophs form the lowest trophic level in the food chain. Heterotrophs form the second or third trophic levels in the food chain.
Solar energy Solar energy can be stored in some autotrophs. Solar energy storage or utilization is not possible in heterotrophs.
Role Autotrophs act as producers. Heterotrophs act as consumers.
Types Autotrophs are of two types; photoautotrophs and chemoautotrophs. Heterotrophs are also of two types; phytotoheterotrophs and chemoheterotrophs.
Organisms Autotrophs are mostly plants, algae, and some bacteria. Heterotrophs are mostly animals, fungi, and some bacteria.
Photosynthesis Photosynthesis acts as the major metabolic pathway for the production of energy. Photosynthesis doesn’t occur in heterotrophs.
Photosynthetic pigments Photosynthetic pigments are usually present. Photosynthetic pigments are absent.
Carbon source Autotrophs use inorganic carbon as the carbon source. Heterotrophs use organic carbon as a carbon source.
External energy source Autotrophs require an external source of energy like sunlight or chemical reactions. Most heterotrophs do not require a separate energy source. Photoheterotrophs might use sunlight as a source of energy.
Availability Autotrophs make food at a particular period of time. Plants make food in the day while chemoautotrophs depend on the chemical reaction. Food is available to heterotrophs almost any time of the day.
Examples Plants, algae, cyanobacteria, etc. Humans, animals, fungi, heterotrophic bacteria.

Examples of Autotrophs

Green Plants

  • The most significant class of autotrophs that use solar energy to combine inorganic substances into organic molecules are green plants.
  • Chlorophyll is a photosynthetic pigment present in plants which absorbs solar energy and converts it to chemical energy through a number of metabolic pathways.
  • Primary consumers, which include herbivores, depend directly on green plants for food and energy, while secondary consumers, like predators, depend indirectly on green plants.
  • The primary trophic level of the food chain is occupied by green plants, which generate the energy that is subsequently distributed all over the entire chain.
  • Plants utilise carbon dioxide, water, and sunlight to produce glucose and oxygen.

Green algae

  • Green algae are another group of organisms capable of producing their own nutrition via photosynthesis.
  • The majority of these photoautotrophs are found in ponds and marshes.
  • These organisms, including plants, contain the photosynthetic pigment chlorophyll to capture the sun’s energy necessary for the process.
  • Green mats of algae grow on the ground, which helps the atmosphere get more oxygen.


  • A genus of nitrogen-fixing bacteria called Nitrosomonas transforms atomic nitrogen into an organic form that may be absorbed by plants in the soil.
  • These organisms, known as chemoautotrophs, prepare their food using the energy generated by chemical reactions.
  • These organisms consume nitrogen, alter it to nitrate form, then subsequently incorporate nitrate form as amino acids into plants.
  • Therefore, they obtain the energy necessary for amino acid synthesis from the nitrogen fixation process.

Examples of Heterotrophs


  • The majority of the species at the consumer’s trophic level of the food chain are animals.
  • All animals are heterotrophs, meaning they rely on plants and their products either directly or indirectly for food and energy.
  • The majority of consumers that get their supply of carbon directly from plants are herbivores.
  • Secondary consumers who eat herbivores for food are carnivores.
  • These creatures acquire carbon in the form of organic material, which is subsequently converted into energy for development and reproduction.
  • Humans are heterotrophs because they are omnivores, eating both plants and animals for food.


  • In contrast to autotrophs, which they do not consume, fungi are heterotrophs.
  • These organisms, known as saprophytes, consume nutrients instead of organic substances.
  • Because decomposing materials offer simpler kinds of energy, the majority of saprophytic fungi may be found there.
  • Before ingesting the meal, they release digestive enzymes that aid in reducing it to smaller pieces.
  • However, certain fungi are parasitic and hence feed on the host, whether or not the host is harmed.
  • In the food chain, fungi play the role of decomposers to assist in cycling the energy back into the atmosphere for the autotrophs to absorb.

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