15 Difference Between Unicellular And Multicellular Organisms (With Examples)

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What Are Unicellular Organisms?

 Unicellular organism, also referred to as single celled organisms, is an organism that consists of a single type of cell. Life processes such as excretion, digestion, feeding and reproduction occur in one cell. They are typically microscopic in nature and cannot be seen with naked eyes. Many unicellular organisms live in extreme environments such as hot springs, thermal ocean vents, polar ice and frozen tundra.

 Examples of Unicellular organisms include:

  • Archaea bacteria
  • Eubacteria
  • Protozoa
  • Diatoms
  • Yeast
  • Rhizobium Vivax
  • Slime molds
  • Paramecia
  • Amoeba
  • Cyanobacteria and other forms of bacteria.

What You Need To Know About Unicellular Organisms

  1. The unicellular organism’s body is composed of a single cell. Life processes like reproduction, digestion, feeding and excretion occur in one single cell.
  2. Examples of unicellular organisms include: Amoeba, Paramecium, yeast, protozoa, cyanobacteria and other forms of bacteria.
  3. The unicellular organisms have an irregular shape.
  4. Unicellular organisms include both eukaryotes and prokaryotes.
  5. The body organization of unicellular organisms can be described as simple. 
  6. The unicellular organisms are of smaller size (microscopic in nature) and most of them are not even visible with naked eyes. They are only visible only under a microscope.
  7. In unicellular organisms, cells play the same role whether for itself or other organisms.
  8. The unicellular organisms are heterotrophs in nature.
  9. Cell differentiation in unicellular organisms is conspicuously absent.
  10. The mode of reproduction in unicellular organisms is primarily asexual.
  11. Division of labor in unicellular organisms is at organelle level.
  12. The overall body cell of a unicellular organism is exposed to the environment.
  13. Usually, the lifespan of unicellular organisms is short.
  14. In unicellular organism, life processes like reproduction, digestion, feeding and excretion occur in one single cell.
  15. Simple diffusion is used as the main transport mechanism in unicellular organisms.

What Are Multicellular Organisms?

Multicellular organisms are organisms that consist of more than one cell. They are usually bigger in size and are very complex and intricate in their composition along with structure. Multicellular organisms arise in various ways for example by cell division or by aggregation of many single cells. Animals have evolved a considerable diversity of cell types in a multicellular body (100-150 different cell types), compared with 10-20 in plants and fungi.

Examples of multicellular organisms include:

  • Human beings
  • Plants
  • Fungi
  • Animals
  • Birds
  • Insects.
  • Polysiphonia
  • Funaria

What You Need To Know About Multicellular Organisms

  1. Multicellular organisms are composed of different types of cells. They are usually bigger in size and are very complex and intricate in their composition along with structure.
  2. Examples of multicellular organisms include: human beings, plants, animals, birds and insects.
  3. The multicellular organisms have a definite shape.
  4. Multicellular organisms only include eukaryotes.
  5. The body organization of multicellular organisms can be described as complex.
  6. Multicellular organisms are of large size and majority of them are visible to the naked eye.
  7. In multicellular organisms, cells have a double role for themselves and other organisms.
  8. Multicellular organisms are both heterotrotrophs and autotrophs in nature.
  9. Cell differentiation is conspicuously present in multicellular organisms.
  10. The mode of reproduction in multicellular organisms is both sexual and asexual.
  11. Division of labor in multicellular organisms is at cellular, organ and organ system level.
  12. The overall body cell of a multicellular organism is not exposed to the environment, only the outer cell.
  13. Multicellular organisms have a longer lifespan when compared to unicellular organisms.
  14. In multicellullar organisms, different cells are specialized to carry out different functions.
  15. Transport mechanisms such as simple diffusion, active and active transport are used in multicellular organisms.

Difference Between Unicellular And Multicellular Organisms In Table

BASIS OF COMPARISON UNICELLULAR  ORGANISM MULTICELLULAR ORGANISM
Description The unicellular organism’s body is composed of a single cell. Life processes like reproduction, digestion, feeding and excretion occur in one single cell.   Multicellular organisms are composed of different types of cells. They are usually bigger in size and are very complex and intricate in their composition along with structure.  
Examples Amoeba Paramecium Yeast  Protozoa Cyanobacteria  Other forms of bacteria.   Human beings Plants  Animals Birds Insects.  
Shape They organisms have an irregular shape.   They organisms have a definite shape.  
Type Of Organism They include both eukaryotes and prokaryotes.   They only include eukaryotes.  
Body Organization The body organization of unicellular organisms can be described as simple.    The body organization of multicellular organisms can be described as complex.  
Visibility They are of smaller size (microscopic in nature) and most of them are not even visible with naked eyes. They are only visible only under a microscope.   They are of large size and majority of them are visible to the naked eye.  
Cells In unicellular organisms, cells play the same role whether for itself or other organisms.   In multicellular organisms, cells have a double role for themselves and other organisms.  
Mode Of Nutrition The unicellular organisms are heterotrophs in nature.   They are both heterotrotrophs and autotrophs in nature.  
Cell Differentiation Cell differentiation in unicellular organisms is conspicuously absent.   Cell differentiation is conspicuously present in multicellular organisms.  
Mode Of Reproduction The mode of reproduction in unicellular organisms is primarily asexual.   The mode of reproduction in multicellular organisms is both sexual and asexual.  
Division Of Labour Division of labor in multicellular organisms is at cellular, organ and organ system level.   Division of labor in multicellular organisms is at cellular, organ and organ system level.  
Body Cell Exposure To Environment The overall body cell of a unicellular organism is exposed to the environment.   The overall body cell of a multicellular organism is not exposed to the environment, only the outer cell.  
 Lifespan Usually, the lifespan of unicellular organisms is short.   They have a longer lifespan when compared to unicellular organisms.  
Cell Specialization In unicellular organism, life processes like reproduction, digestion, feeding and excretion occur in one single cell.   In multicellullar organisms, different cells are specialized to carry out different functions.  
Transport Mechanism Simple diffusion is used as the main transport mechanism in unicellular organisms.   Transport mechanisms such as simple diffusion, active and active transport are used in multicellular organisms.  

What Are Some Of The Similarities Between Unicellular And Multicellular Organismis?

  • Both unicellular and multicellular organisms contain ribosomes and DNA.
  • They both reproduce and exhibit similarity in the functions of metabolism.
  • Both have cytoplasm and cell membrane.
  • In both case, there cells undergo cell division, either by mitosis or binary fusion.