Symbiosis Definition

Table of Content:

Symbiosis – Definition Symbiosis – Types Frequently Asked Questions

Symbiosis – Definition

Symbiosis refers to the close relationship amongst two different organisms or living things belonging to different species.

Symbiosis is a relationship that exists between two organisms. There are three types of behaviours observed in symbiotic relationships, namely:

  • Mutualism
  • Commensalism
  • Parasitism

Symbiosis – Types

  • In mutualism, both the involved organisms benefit from each other. Example – Coral reefs are nothing but a mutualistic association between coral organisms and various types of algae residing inside them.
  • In commensalism, only one organism benefits, while the other is neither benefited nor harmed. Example – Hermit crabs use gastropod shells to protect their bodies.
  • In parasitism, one organism is benefited while the other organism is harmed. Example – Liver fluke attaches itself to the liver and makes its way to the tissue and bile.
Interaction  Species A Species B 
Mutualism + +
Commensalism + 0
Parasitism +

Understanding symbiotic relationships are important, as it helps us understand how various organisms are dependent on each other for survival.

Main Article: Parasites And Symbiosis – Definition, Types, Examples

Frequently Asked Questions


Define symbiosis.

Symbiosis is defined as a relationship or interaction between two different organisms that share similar habitat. There are three types of behaviours observed in symbiotic relationships, namely – Mutualism, Commensalism and Parasitism.


What are the examples of symbiosis?

Lactobacillus and humans, cells and mitochondria, ants and fungi, goby fish and snapping shrimp, coral and algae, and cleaner fish are some examples of symbiosis.

Further Reading:

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