Mutualism is a natural phenomenon – a sort of interaction or partnership which occurs between two different organisms from separate species. The beauty of mutualism is that both organisms benefit from this partnership. Examples of mutualism in nature are aplenty. 

After you read and understand this chapter, you will able to define mutualism with ease. You will also appreciate the role mutualism plays in ecology.

For many years, ecologists have ignored the importance of mutualism. Biologists have only recently discovered that mutualism examples have been hiding in plain sight and that this phenomenon is older than was once thought.

It is now widely accepted that mutualism existed at least 100 million years ago. That was when dinosaurs ruled the Earth! 

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What is Mutualism?

In strictly scientific terms, mutualism is defined as a natural interaction between individuals from totally different species which exists for the benefit of each other. These benefits may include passive aid in reproduction and sometimes even survival.

Each of these individual organisms is termed a mutualist.

Mutualism definition in biology has changed several terms since the phenomenon was first identified. Initially, it was confused with symbiosis. Later, as interspecific (or inter-species) interactions were studied, mutualism was regarded as a separate phenomenon.

You can research more on the differences and similarities between mutualism, symbiosis, parasitism and other types of inter-species interactions. Using this data, you can then try and write a short note on mutualism. 

It will help you in your preparations before your exams.

Types of Mutualism

It would help if you now learned about the significant varieties of mutualism.

  1. Facultative Mutualism – 

Here, two organisms will coexist opportunistically only. That is, they do not depend or rely on each other for nutrition, reproduction or any other purpose.

A good example is honey bees flying from one flower to another in search of nectar. Unknowingly, these insects act as pollinators. This ubiquitous event results in cross-pollination.

  1. Trophic Mutualism –

Here, two specific types of organisms, each having skills complementing one another, interact to survive and feed.

If you are asked to give an example of mutualism, you can use trophic examples. There is a very special relationship between leaf-cutter ants (Atta colombica and Acromyrmex balzani are good examples) and fungus. 

These ants bring into their nests leaves for feeding. These leaves are then literally ‘cultivated’ by ants to grow fungi, specifically of the Lepiotaceae species. Ants actively protect these fungi. In return, the fungi produce hyphal tips which these ants eat.

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Fun Fact: Did you know leaf-cutter ants can carry loads of up to 20 times their weight? You can easily imagine why there is a superhero who has ant-like powers!

  1. Defensive Mutualism –

Here, two organisms cooperate to protect each other. One mutualist may receive nutrition in exchange for providing security to the other mutualist. Some of the most unique examples of mutualism in nature are defensive ones.

Shrimps and fishes often stay together in seawater where shrimps ‘clean’ fishes of parasites lodged in their gills. These parasites are the food of such shrimps; in return, these fishes never feed on such shrimps. 

Such interactions are also known as ‘cleaner mutualism’.

Given below are two mutualism examples with pictures, specifically of this defensive type.

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  1. Obligate Mutualism –

This last major type involves two fully interdependent species. Without one, the other will not survive in nature.

Algae and fungi come together to form lichens. This is the best example of mutualism in nature.

Quiz For You:

  • Which of these factors come in lay in defensive mutualism?

Option A: A steady source of food.

Option B: Parasite removal.

Option C: Protection from predators.

Option D: All of these factors.

The answer to the quiz is option 4.

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FAQ (Frequently Asked Questions)

1. Are Mutualism and Symbiosis the Same?

Ans. No, they are two different types of interspecific interactions. Symbiosis may often be the result of mutualism.

2. How many types of Mutualisms exist in Nature?

Ans. There are multiple ones; the most common are obligate, defensive, trophic and facultative.

3. Can the Relationship Between Trees and Mankind be Considered a Mutualism?

Ans. Yes. It is a form of mutualism. It is perhaps the most crucial form.