Difference between Autotroph and Heterotroph

When studying organisms and the ecosystem two of the words you will encounter are autotroph and heterotroph.

It is important to know the differences between the two and that’s what we are going to discuss in this article.

What is an Autotroph

Autotrophs are organisms that have the ability to produce their own food without help from others. It comes from the two words auto, which means self, and troph, which means food.

In the food chain, autotrophs are on the base because other organisms rely on them to survive.

Examples of Autotrophs

  • Plants
  • Green algae
  • Phytoplankton
  • Some types of bacteria such as Nitrosomonas or nitrogen-fixing bacteria. (1, 2, and 3)

What is Heterotroph

Heterotrophs are organisms that rely on other organisms for food. They do not have the ability to make their own food. It comes from the words hetero, which means others, and troph, which means food.

In the ecological food chain, they are called consumers because they consume the products of autotrophs.

Examples of Heterotrophs

  • Parasites
  • Animals
  • Fungi (4, 5)

Refer to the table below for a detailed comparison between autotroph and heterotroph.

difference between Autotrophs and Heterotrophs

 

Key differences Autotrophs Heterotrophs
Meaning/definition Organisms that have the ability to make their own foods. (4, 5) Organisms that don’t have the ability to make their own food. They rely on autotrophs to survive. (5)
Etymology
  • Auto – self
  • Troph – food
  • Hetero – others
  • Troph – food
Energy source Autotrophs’ source of energy is sunlight. Although they could also benefit from some types of chemical reactions. (5, 6) Heterotrophs’ source of energy is the autotrophs.
Trophic level In the food chain, autotrophs are found at the lowest level. In the food chain, you can find heterotrophs in the second or third trophic level. (6)
Solar energy storage Some autotrophs have the ability to store solar energy. Heterotrophs don’t have the ability to store and use solar energy.
Dependency They are fully independent as shown in their ability to make their own foods. (7, 8) They are dependent on autotrophs.
Role in the food chain They are the producers primarily because they provide food for other organisms. They are the consumers; they consume the foods created by the producers. (7, 8)
Types There are different types of autotrophs but the most common are the following:

Photoautotrophs – They get their energy from sunlight which will be used to make organic materials.

Examples of photoautotrophs are:

  • Plants
  • Algae
  • Bacteria (6, 7)

 

Chemoautotrophs – These autotrophs get energy from inorganic chemical processes. Some of the volatile chemicals used by chemoautotrophs are hydrogen sulfide, molecular hydrogen, ferrous iron, elemental sulfur, and ammonia.

Examples of chemoautotrophs are archaebacterial. (7, 8, and 9)

Heterotroph types include the following:

Carnivores – They are predators as they eat only meat and other organisms.

Examples: are jaguars, lions, and snakes.

Omnivores – They eat both plants and animals.

Examples: are humans, dogs, and cats.

Herbivores – They are heterotrophs that eat plants such as horses and cows.

Decomposers – They use enzymes and some form of chemical reactions to break down living organisms.

Examples are bacteria, fungi, flies, beetles, and earthworms. (9,10)

Photosynthesis They are the primary metabolic pathway for energy production. (4) Heterotrophs don’t go through the process of photosynthesis.
Presence of photosynthetic pigments Present Absent
Source of carbon Inorganic carbon Organic carbon
Locomotion Autotrophs don’t have the ability to move from one place to another. (5, 6) Heterotrophs have the ability to move around, which is helpful when searching for food and shelter. (9)
External energy source They need external energy such as sunlight and/or chemical reactions. The majority of heterotrophs do not need a separate energy source. (8)
Availability They create food at a specific period of time. for example, plants usually make foods during the daytime.

Chemoautotrophs need to rely on a chemical reaction to make food. (8, 9, and 10)

Foods are readily available at any time of the day. (9)
Examples Some of the examples of autotrophs are plants, green algae, phytoplankton, and nitrogen-fixing bacteria. (6, 7) Examples of heterotrophs are humans, animals, heterotrophic bacteria, fungi, and parasites. (4, 6)

Key points to keep in mind when studying autotrophs and heterotrophs.

  • Autotrophs and heterotrophs are used to classify organisms based on nutrition. Organisms that can make their own food are called autotrophs while those relying on autotrophs for food and survival are called heterotrophs.
  • In the food chain, autotrophs are the producers while heterotrophs are the consumers. Autotrophs are placed first in the food chain while heterotrophs take the second and/or third levels.
  • Both autotrophs and heterotrophs are useful in maintaining the balance of energy in the ecosystem.
  • There are organisms that are both autotrophs and heterotrophs. They are cyanobacteria; exhibiting photoautotrophic nutrition. Another example is the archaea.
  • Although autotrophs have the ability to make their own food, they cannot move from one place to another. On the other hand, heterotrophs are locomotive; meaning they can move from one place to another, but they can’t make their own food. They need to rely on autotrophs.
  • When it comes to an energy source, autotrophs get their energy from inorganic sources and convert light energy into chemical energy. On the other hand, heterotrophs have to rely directly or indirectly on other organisms for an energy source. (4, 6, 9, and 10)

Autotrophs and heterotrophs are both vital parts of the ecosystem, especially in maintaining the balance between the supply and demand of organisms.

These kinds of nutrition constitute the equilibrium in the biosphere’s food chain.

Can autotrophs survive without heterotrophs?

The answer is : Yes.

However, there will be an imbalance in the ecosystem. Hence, autotrophs and heterotrophs go hand in hand. The only obvious distinction is that autotrophs are self-feeders while heterotrophs are other feeders.

At the end of the day, it is a must to maintain a balance in the ecosystem. Failure to achieve balance could lead to chaos. (2, 5, and 9)

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