Types of microorganisms | Their Examples with Pictures

Microorganisms are living beings that are not visible to the naked eye.

They can be viewed only with the help of a microscope.

In spite of their minute in size, they carry out their body functions and physiology independently like higher animals.

These organisms are mostly single cellular and very few are multi-cellular.

The differences among microbes can be learned based on their structure, physiology, habitats and also food habits.

Types of Microorganisms

  1. Bacteria
  2. Archaea
  3. Algae
  4. Fungi
  5. Protozoa
  6. Yeast
  7. Diatoms
  8.  Virus


These are said to be the first organisms to have appeared and are single cellular. The cell has a cell wall and also flagella.

They are called “prokaryotic cells” due to a lack of a clear-cut nucleus.

Bacteria are omnipresent, i.e., they can be found on the earth’s surface, underneath, in the air, in the living bodies, etc.

types of microorganisms
Microscopic view of Listeria monocytogenes. (by- Getty)

They obtain their food by different means like parasitic nature, saprophytic, symbiotic methods, etc.  They eat up almost anything, due to which the waste gets decayed.

Bacteria cause many diseases like tuberculosis, leprosy, cholera, etc.


These are similar to bacteria but live in more harsh conditions and extreme temperatures. They differ from bacteria in few biochemical molecules.


These multi-cellular yet microscopic in nature.

Freshwater algal bloom, LM-Getty images

They can be seen when they grow in large colonies as patches. They live in marine and also freshwater environments.

Ex: Spirogyra.


These are multi-cellular and some of them are microscopic while others are macroscopic. They grow on bread and other foodstuffs at home. They can be invisible when present as single strands. But as they grow into a bunch of strands, they can be visible as fluffy material.

Ex: Rhizopus.

Fungi cause topical infections like ringworm and deranged nails on toes. They can also cause internal infection. But there are few important uses of fungi.

ameoba a protozoa
Amoeba a protozoa single-celled animal


These are a large class of animals that are visible only under a microscope. They have the ability to move and find their food. They can cause diseases in man and other large animals. They are mostly found in fresh water and in slimy moist soil.

Ex: Amoeba.

You can read more about them at examples of protozoa.

Diseases caused by protozoa include malaria, gingivitis, etc. These are examples of the single-celled parasites.


These are classes of fungi but are single-celled. They are some of the widely used organisms for human purposes like the production of alcohol, baking as nutritional supplements, etc.


These are a type of micro-algae enclosed in the cell wall made of silica. They are mostly present in fresh water and marine water.


These are not living organisms. But this virus is a biological agent which on entering into living being, takes up host nuclear machinery and multiply.

They are absolute parasites and cannot live without a host. They have a protein coat and nucleic acid-like DNA or RNA. They cause many types of diseases in plants and animals.

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