What are the 3 Types of Nutrition? [The Final Answer]

We eat food to get the nutrition.

But, did you think, how plants or bacteria get nutrition to survive?

Evolutionarily there is no single way to get nutrition. It is a complex process that has been modified over several million years of evolution.

The nutrition process is different for different organisms.

In my previous post I have discussed what is nutrition. In this post I will discuss about the types of nutrition.

Let’s get started.

Table of Contents

Types of Nutrition

There are two types of nutrition among living organisms: autotrophic nutrition and heterotrophic nutrition (1). There is another type of nutrition exists, which is called mixotrophic nutrition (2).

Let’s discuss one by one in detail.

Autotrophic Nutrition

In this mode of nutrition, organisms can produce their own food (3). These organisms are called autotrophs or autotrophic organisms, or primary producers.

Autotrophs use carbon dioxide as the only carbon source and light or chemicals as an energy source.

There are two types of autotrophic nutrition: photosynthesis and chemosynthesis.

Photosynthesis

Organisms like plants, algae, and cyanobacteria use light as an energy source, are called phototrophs or photoautotrophs, or photolithoautotrophs. They follow a procedure called photosynthesis. With this procedure, they absorb sunlight by their pigments for energy.

Chemosynthesis

Even though phototrophs depend on light for their survival, some can grow under very low light conditions.

For example, organisms like certain bacteria use chemicals or inorganic compounds as an energy source. They are called chemotrophs or chemoautotrophs, or chemolithoautotrophs.

They can’t use sunlight for energy because they live in deep water, and sunlight can not reach there.

Bacteria follow a procedure called oxidation. They oxidize or break down inorganic compounds like hydrogen sulfide, ammonia, sulfur dioxide, or ferrous ions to produce energy. The procedure is called chemosynthesis.

Heterotrophic Nutrition

In this mode of nutrition, organisms use already prepared substances, either by autotrophs or heterotrophs, is called heterotrophic nutrition (4). These organisms are called heterotrophs or heterotrophic organisms.

Heterotrophs use organic compounds as a carbon source and produce inorganic compounds such as carbon dioxide as a waste product. Autotrophs use these inorganic waste products to produce their food. It creates a cycle called the nutrient cycle.

I will discuss it later in a separate post.

Heterotrophic organisms include animals, fungi, bacteria, and protozoa.

These organisms get their energy by breaking down the molecules of the autotrophic organisms that they have eaten. Even carnivorous animals indirectly depend on autotrophs because the organisms they eat depend on autotrophs for living.

Different heterotrophic organisms get their nutrition in different modes. For example, parasitic, saprophytic and holozoic (5).

Let’s discuss one by one.

Parasitic Nutrition

In this mode, heterotrophic organisms live inside or outside of other organisms and obtain their food by ingestion or absorption. These heterotrophs harm their host. Those who live inside their host are called endoparasites. Those who live outside or surface of their host are called ectoparasites.

Saprophytic Nutrition

In this mode, heterotrophic organisms live freely and get their nutrients from the environment. They break those nutrients by enzymes to get the energy. For example, fungi follow saprophytic nutrition. They are responsible for staling our bread.

Holozoic Nutrition

In this mode, heterotrophic organisms ingest food and digest them to obtain nutrition. For example, humans follow holozoic nutrition.

Now, holozoic nutrition can be classified further into three categories:

  1. Herbivorous nutrition: Food source is vegetables
  2. Carnivorous nutrition: Food source is meat
  3. Omnivorous nutrition: Food source is both vegetables and meat.

Symbiotic Nutrition

In this mode, heterotrophic organisms share their food with hosts. This mutual relationship may or may not be beneficial to both organisms. For example, lichens establish symbiotic relationships with fungi and plants.

According to the origin of energy, heterotrophic organisms can be divided into two categories:

Photo-heterotrophic nutrition

In this mode, heterotrophic organisms use light as a source of energy. For example, purple bacteria are heterotroph and gets carbon by absorbing organic matters and energy by absorbing sunlight.

Chemo-heterotrophic nutrition

In this mode, heterotrophic organisms use chemical compounds like carbohydrates, protein, and fat as energy sources. For example, all the members of animal kingdom and fungi, a large part of moneras and archaebacteria, use these chemical compounds for energy. 

Mixotrophic Nutrition:

In this mode, heterotrophic organisms can get carbon from carbon gas as well as organic carbon. In other words, they show both characteristics of autotrophic nutrition and heterotrophic nutrition (6). These organisms can use light as an energy source or take it from organic or inorganic compounds.

For example, euglena has chloroplast for making their food by photosynthesis; however, they can also absorb nutrition from the environment. They usually live in quiet ponds or puddles.

Summary

Every living creatures need nourishment to survive. Different organisms get their nutrition in different way. Some can produce their food by their own and some are dependent to someone. This created a nutrition cycle and it continue till the end of the earth.

FAQ

How many types of Nutrition are there?

There are two types of nutrition among living organisms: autotrophic nutrition and heterotrophic nutrition. There is another type of nutrition that exists, which is called mixotrophic nutrition.

How many types of Heterotrophic Nutrition are there?

There are four types of heterotrophic nutrition among living organisms: parasitic nutrition, saprophytic nutrition, holozoic nutrition, and symbiotic nutrition.

What are the different types of Autotrophic Nutrition?

There are two types of autotrophic nutrition among living organisms: chemosynthesis and photosynthesis.

What is the difference between Autotrophic and Heterotrophic Nutrition?

The main difference is, in autotrophic nutrition, organisms prepare their own food. But in heterotrophic nutrition, organisms do not prepare their own food. In the food chain, autotrophs are also called producers, and heterotrophs are called consumers.

Which organisms are both Autotrophs and Heterotrophs?

Some unicellular organisms carry both autotrophic and heterotrophic nutrition. For example, euglena has chloroplast for making their food by photosynthesis; however, they can also absorb nutrition from the environment.

What is another name for Heterotroph?

Another name of heterotroph is the consumer because they can’t produce food and depends on autotrophs or other heterotroph organisms for food.

What is another name for Autotrophs?

Another name of autotroph is the producer because they produce their own food.

Are humans carnivores or herbivores?

Humans are omnivore animals but are more herbivores and less carnivores because most of our diet comes from plants and less from animals.

Can Humans be Autotrophs?

No. Humans can’t be autotrophs because humans can’t do photosynthesis. Also, our glucose demand is higher than photosynthesis can accommodate.

References

This article is written by certified nutritionist and verified by scientific evidence. We relies on reputed and specialized media sites, academic research institutions, peer-reviewed studies, government agencies, and medical associations to source information. We avoid using tertiary references. Know more about how we ensure our content is accurate and current by reading our editorial policy.

  1. Admin. Nutrition In Living Organisms & Modes Of Nutrition. BYJUS. https://byjus.com/biology/nutrition-modes-living-organisms/. Published February 26, 2021. Accessed April 14, 2021.
  2. WEITHOFF G, WACKER A. The mode of nutrition of mixotrophic flagellates determines the food quality for their consumers. Functional Ecology. 2007;21(6):1092-1098. doi:10.1111/j.1365-2435.2007.01333.x
  3. National Geographic Society. Autotroph. National Geographic Society. https://www.nationalgeographic.org/encyclopedia/autotroph/. Published October 9, 2012. Accessed April 14, 2021.
  4. National Geographic Society. Heterotrophs. National Geographic Society. https://www.nationalgeographic.org/encyclopedia/heterotrophs/. Published May 20, 2019. Accessed April 14, 2021.
  5. Admin. Heterotrophic Nutrition (Definition, Types & Examples). BYJUS. https://byjus.com/biology/heterotrophic-nutrition/. Published February 4, 2021. Accessed April 14, 2021.
  6. WEITHOFF G, WACKER A. The mode of nutrition of mixotrophic flagellates determines the food quality for their consumers. Functional Ecology. 2007;21(6):1092-1098. doi:10.1111/j.1365-2435.2007.01333.x

A. R. Choudhury is a certified nutritionist, author, and blogger with a passion for evidence-based nutrition. He completed "Stanford Introduction to Food and Health" certificate course by Stanford University from Coursera Inc. He received his master's degree in biochemistry from The University of Burdwan. Abdur Rahman Choudhury aka A. R. Choudhury is also a fitness enthusiast and a coffee lover.

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