Facts about the animal kingdom

Autotrophic and Heterotrophic Organisms

Josie F. Turner
By Josie F. Turner, Journalist specialized in Animal Welfare. July 29, 2018
Autotrophic and Heterotrophic Organisms

All of the beings on earth are nourished in different ways. One of the main reasons for this nourishment is to turn it into energy for their physical activity. We know that animals get this nourishment from eating food, but what happens with other beings such as algae which don't have a mouth and/or digestive system.

In this AnimalWised article, we will look into the autotrophic and heterotrophic organisms. One of the first things we should point out is the fact that not everything which consumes for energy is an animal. This is why we not only provide a definition for the terms, but examples of the different species and beings which fall under the two categories.

You may also be interested in: What Are Scavenger Animals?
  1. Definition of autotrophic and heterotrophic
  2. Background on autotrophic and heterotrophic nutrition - differences and comparisons
  3. Examples of autotrophic organisms
  4. Examples of heterotrophic organisms

Definition of autotrophic and heterotrophic

Before we explain the definition of autotrophic and heterotrophic, we should provide a little basic background on carbon. Carbon is the chemical element which is part of all known life on our planet. The reason for this is likely to do with its ability of structuring itself in so many different ways. In doing so, it establishes links with a multitude of chemical elements, its light weigh structure making it the perfect element for life. We are all made of carbon and, one way or another, we need to take it from the environment around us.

Both the words heterotrophic and autotrophic derive from the Greek language. The word ‘autós’ means ‘on its own’, ‘heterós’ means ‘other party’ and ‘trophe’ means ‘nourishment’. By understanding this etymology, we can help show you that an autotrophic being is one which creates its own food and heterotrophic beings are those which require another being to feed themselves.

Autotrophic and Heterotrophic Organisms - Definition of autotrophic and heterotrophic

Background on autotrophic and heterotrophic nutrition - differences and comparisons

Autotrophic nutrition

Autotrophs create their own food by a process known as fixing carbon or ‘carbon fixation’. This is the process of obtaining carbon directly from carbon dioxide (inorganic carbon) by assimilating it into organic compounds. his is then used in the organic cells of the various autotrophic organisms. One of the most common processes of carbon fixation is known as photosynthesis.

Autotrophs can be photoautotrophic or chemoautotrophic. Photoautotrophs use light as an energy source to fox and assimilate carbon for nourishment. Chemoautotrophs use other chemicals as an energy source. These may include hydrogen sulphide, elemental sulfur, ammonium and ferrous iron. All plants, some bacteria, archaea (single-cell organisms without a nucleus) and protists (non-plant, non-animal or non-fungus yet has cells with nuclei) get their carbon in this way.

Photosynthesis is the process by which green plants and other organisms convert light energy into chemical energy. During photosynthesis, the light energy is captured by an organelle called chloroplast. This is present in these cells and is used to convert water, carbon dioxide and other minerals into ocygen and other organic compounds rich in energy.

Heterotrophic nutrition

On the other hand, heterotrophic beings obtain their food from organic sources present in their environment. They cannot transform inorganic carbon into organic carbon. This means they need to eat or absorb materials which have organic compound such as plants and animals. This organic carbon can come from any living being and its waste which includes everything from microscopic bacteria to large mammals.

There are two types of heterotrophs; photoheterotrophs and chemoheterotrophs. Photoheterotrophs use light energy to convert into different types of energy, but they need organic matter as a carbon source. Chemo-heterotrophs get their energy through a chemical reaction that releases energy by breaking down organic molecules. For this reason, both photoheterographic and chemoheterographic organisms need to eat living or dead organisms to obtain energy and process organic matter.

In summary, the difference between autotrophic and heterotrophic beings are the way in which they obtain nourishment. Most animals are heterotrophic, whereas there are few autotrophic animals, perhaps even none depending on the state of the debate.

Examples of autotrophic organisms

  • Green pants and algae are one of the most efficient types of autotrophs. They are photoautotrophs which use light as an energy source. These organisms are fundamental to the food chains of all the world’s ecosystems.
  • Iron-oxidizing bacteria are chemoautotrophs as they obtain energy and food from the inorganic substances that exist in the environment. We can find these bacteria in iron-rich soils and rivers.
  • Sulfur bacteria are also chemoautotrophs which live in accumulations of pyrite which is a mineral made of sulfur from which they feed.
Autotrophic and Heterotrophic Organisms - Examples of autotrophic organisms

Examples of heterotrophic organisms

  • Herbivores, omnivores and carnivores are all heterotrophs because they feed on other plants and animals.
  • Fungi and protozoa absorb organic carbon from their environment and are chemoheterotrophs.
  • Purple non-sulfur bacteria are photoheterotrophs which use organic acids without sulfur top obtain energy. The carbon is obtained from organic matter.
  • Heliobacteria are different types of photoheterotrophs which require sources of organic carbon found in the soil especially in rice crops.
  • Manganeze oxidizing bacteria are a type of chemoheterotroph which uses volcanic rock to obtain energy, but it will depend on their environment as to how they get organic carbon.

If you want to know more about the taxonomy of the animal kingdom, you might want to look at some examples of carnivorous animals and then compare them with herbivorous animals.

Autotrophic and Heterotrophic Organisms - Examples of heterotrophic organisms

If you want to read similar articles to Autotrophic and Heterotrophic Organisms, we recommend you visit our Facts about the animal kingdom category.

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Autotrophic and Heterotrophic Organisms