Difference Between Unicellular And Multicellular Organisms

Every living organism on this planet is made up of cells, and these cells help in the proper functioning of this living organism. There can be one or more cells in a living organism, and an organism with a single cell is known as a unicellular organism, while on the other hand, organisms with multiple cells are known as multicellular organisms. 

What is a Unicellular Organism?

A unicellular organism or commonly referred to as a single-celled organism is an organism made up of a single cell and these organisms rely on this single cell for all their functionality. These unicellular organisms are further divided into two categories i.e. eukaryotic and prokaryotic. Eukaryotic are multicellular organisms whose cell contains the nucleus and other organelles, while on the other hand, most prokaryotic are unicellular in which the nucleus is absent. These unicellular organisms are considered to be the oldest living organisms, whose occurrence dates around 4 billion years ago. Amoeba, plasmodium, euglena, algae, protozoa, paramecium, and fungi are some of the common unicellular organisms.

What is a Multicellular Organism?

Just opposite to unicellular or single-celled organisms, multicellular organisms are one that contains multiple cells, which work together to achieve the proper functionality in that living organism. In Multicellular organisms, different cells are responsible for different tasks. Almost all species of land plants and animals are multicellular, however, some plants and bacteria can be partially multicellular as well. These multicellular organisms are the result of cell division or a combination of cells. Humans, dogs, cows, cats, trees, chickens, and other animals are examples of multicellular organisms.

Difference Between Multicellular and Unicellular Organisms?

Unicellular Organisms	Multicellular Organisms
Made up of a single cell	Made up of a combination of multiple cells
The whole cell is exposed to the outer environment	Only outer cells are in contact with the environment
It usually has a shorter lifespan	It has a longer lifespan
The body formation is quite simple	The body formation is quite complex in nature
Both eukaryotes and prokaryotes fall into this category	Only eukaryotes come under this category
The whole life process is controlled by a single cell	Multiple cells together are responsible for proper functioning
These species are microscopic in nature	Most of these organisms are macroscopic in nature
Unicellular organisms can be either autotrophs or heterotrophs	Multicellular organisms are both autotrophs and heterotrophs
Any serious injury to a cell can lead to death	Any physical damage to a cell doesn’t lead to death
Bacteria, yeast, amoeba, and paramecium falls under unicellular organisms.	Humans, plants, animals, and birds fall under multicellular organisms.

Conclusion

Both unicellular and multicellular organisms have different body structures the unicellular organisms are more prone to extreme temperatures and are thus often called extremophiles. Unicellular organisms can sustain extremely cold to extremely hot temperatures. While on the other hand, normally multicellular organisms can resist extreme temperatures. For example, a small injury or physical damage to a multicellular organism doesn’t lead to death but can surely lead to death in unicellular organisms. Apart from body construction, unicellular organisms rely upon a single cell for whole-body functions, while multicellular organisms rely on multiple cells. 

FAQs on Multicellular and Unicellular Organisms

Q1. Can unicellular organisms reproduce?

Ans: Yes, reproduction occurs in unicellular organisms as well, by binary fission.

Q2. A virus is a unicellular or a multicellular organism?

Ans: A virus is an acellular organism, neither unicellular nor multicellular.

Q3. When did the first multicellular organism was found?

Ans: The first multicellular organism was found 600 million years ago and is called a simple sponge.

Q4. Which is more advantageous unicellular or multicellular?

Ans: Multicellularity is a bit more advantageous as it has a longer life span and can handle physical damage.