3 Types of Nutrition

This article will provide you the all information regarding 3 Types of Nutrition. These three types are the main types of nutrition. It is necessary for the survival of the organisms. Energy is crucial for living organisms to perform different functions. So, energy comes from the food that living things ingest. In addition, food is a substance which living organisms take orally. It is a collection of many chemicals and substances. These chemicals are important for the growth, development, repair and maintenance of the body.

3 Types of Nutrition
3 Types of Nutrition

Hence nutrition is the process by which living organisms gain energy and food for the proper functioning of the body. digestion occurs after ingestion. It is the breakdown of insoluble macromolecules to the soluble simpler molecules so that they can easily absorb into the body.

3 Types of Nutrition in living organisms

There are  3 Types of Nutrition in living organisms.

1 Autotrophic Nutrition

2 Symbiotic Nutrition

3 Heterotrophic Nutrition

Autotrophic Nutrition

It is one of the types of nutrition. In it, high energy organisms obtain energy or food from low energy inorganic molecules present in surroundings. Sources of carbon and nitrogen are carbon dioxide and nitrates respectively. Some bacteria and green plants acquire their energy in the presence of sunlight. Finally, the result of autotrophic nutrition is glucose formation.

Symbiotic Nutrition

In this type of nutrition, two living organisms live together. They share their nutrition with each other.

For Instance:

  • E.coli (Escherichia coli) lives in the intestine of humans. E.coli from vitamin B12. Humans take vitamin B12. In return, E.coli receives food from the intestine of humans.
  • Bacteria Rhizobium lives in the roots nodule of leguminous plants. It fixes nitrogen into nitrates from the atmosphere and transfers it to the soil. Therefore, plants absorb nitrates.it is beneficial to plant growth. As a result Rhizobium bacteria get nutrition from plants.

Heterotrophic Nutrition

In heterotrophic nutrition energy or food collected from feeding on other living organisms. Moreover, there are three further types of heterotrophic nutrition.

  • Holozoic Nutrition
  • Saprophytic Nutrition
  • Parasitic Nutrition

1 Holozoic Nutrition

In holozoic nutrition, the living organisms engulf the food. The engulfed food is then digested and absorbed in the body.

For example humans.

Steps in holozoic nutrition

The following steps are included in holozoic nutrition

  • Digestion
  • Absorption
  • Assimilation
  • Excretion
    Some unicellular organisms also undergo holozoic nutrition.

Holozoic nutrition in Ameoba

  • Firstly, the amoeba extends its pseudopodia and surrounds the food. Then phagocytosis occurs and food engulfs.
  • Amoeba having large food vacuoles that containing digestive enzymes. Secondly, these enzymes breakdown the food particles and convert them to simpler substances. This process is known as digestion.
  • Finally, the digested material is absorbed into the cytoplasm. It left the undigested material behind. Absorbed food is used in growth and development.
  • As a result, the undigested matter is excreted out by cell membrane rupture.

Types of holozoic nutrition

Herbivores: organisms that obtain their food from plants source only
For example buffaloes, cows and elephants etc.

Carnivores: organisms that obtain their food from animal source only
For instance lions, tigers.

Omnivores: organisms that obtain their food either from plant or animal sources.
For instance cockroach, chimpanzee etc.

2 Saprophytic Nutrition

Saprophytic nutrition is not included in ingesting solid food particles. In this type of nutrition, the organisms secrete some digestive enzymes on the dead matter. The process of digestion occurs outside of the body.

For example Spiders, Houseflies etc.

3 Parasitic Nutrition

The food obtains from the host by living on or inside the host body. In parasitic nutrition, the host may or may not harm.
For instance: roundworm, tapeworm, plasmodium and taenia etc.
The bacteria Cymothoa exigua lives in the mouth of marine fish Lithogathus. It is also known as a tongue-eating louse. This bacteria cut off the blood supply of the fish’s tongue and it falls off. However, the louse attaches to the remaining tongue. Now it acts as a new tongue of fish.


There is enough knowledge about the 3 Types of Nutrition. Some living organisms obtain their food from their surroundings. Some organisms depend on others for their shelter and nutrition. Nutrition not only provides the body with energy but also aid in growth and development. Humans get their energy and food from plant and animal sources. Digestion occurs through which nutrients absorb in the body. it helps in the maintenance, repair and life process of living creatures.


You can also see these articles:

Important nutrients and their functions in the human body

Types of Physical Activity

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