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What are the Types of Interactions Between Organisms?

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Types of interactions Between Organisms: An Introduction

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The earth is full of rich and varied biota. The living organisms on earth have a relationship with the other living and non-living things to survive and function efficiently. Both elements are incomplete without the other, which adds to the beauty of the rich diversity of flora and fauna. Living organisms like plants, animals, birds, insects, and micro-organisms depend on other living beings for food, water, shelter and protection. They also depend on non-living entities such as energy from sunlight, minerals and nutrients from the soil, air, rainfall etc.

Ecosystem Interactions

The association of living beings with non-living entities in an environment forms an ecosystem. Ecology is referred to as the study of ecosystems. The living components are called biotic, while the non-living components are called abiotic. Species interactions involving living beings are called biotic interactions.

Population and Community

A group of similar organisms living in an area forms the population. At the same time, the population of different living beings living together in this area is called a community. This contributes to the richness of organisms that we have on our planet.

Types of Ecological Interactions

Interaction is a necessity for any living being to survive. Like human relationships, ecological interactions involving animals, plants, microbes etc., also have negative and positive interactions. These biotic interactions might be intra-specific (interactions between same species) or inter-specific (including interactions between distinct species).


It is an ecological interaction in which one organism kills and feeds on the other. The hunter organism in this interaction is called the predator, and the unfortunate organism that serves as the food is called the prey. Example: wild animals like tigers, lions attacking the zebra, deer, cattle, etc.


When two different species fight or compete with each other for the same resource, this form of interaction is termed competition. The animals could compete for resources like food, support, shelter, space, etc. Organisms are compelled to follow this type of ecological interaction for their survival or existence. Such ecological interaction could either lead to the extinction of one of the parties or the extinction of both parties.

This relationship could be between identical organisms termed intraspecific competition, or intraspecific interaction between organisms of dissimilar kinds termed interspecific competition. Therefore, this ecological interaction allows only the best competitor to survive and pass this trait to their offspring, thus, maintaining the community structure. For example, competition for a berry will be fierce if only two species of birds from different species eat it.


It is an interaction in which one organism, the parasite, benefits or profits while the other organism, the host, is harmed. In such an association, the parasite is found to live within or upon the host's body. Depending on the type of parasite involved, the parasitism may be termed ecto-parasitism or endo-parasitism.

Example: Ticks present on the fur of dogs. Harmful ticks reside on the dog’s fur and obtain shelter from the fur. The ticks harm the dog by lavishly feeding on its blood and causing it to itch. In some cases, these ticks are a source of the carrier of diseases, infecting the animals they live on.


It is a one-sided beneficial relationship between two living organisms, where one organism reaps benefits like food or shelter from the other organism without benefiting or harming it. The partners that profit from such a kind of association are commensal, while the latter organism is the host species. A well-known illustration of a commensal is the remora (family Echineidae), a fish that travels in close proximity to sharks and other fish.

Example: Remoras have developed a flat, oval-sucking disc structure on top of their heads that attach to the bodies of their hosts.


Here, the living beings benefit from each other’s company. This is a positive, friendly relationship. A mutualistic interaction comprises two species of organisms that work together, each benefiting from the relationship. A classic example of Mutualism is pollination, as the hungry bee gets its nectar from the flower, and in return, the flower is pollinated by the bee so it can reproduce.


The ecological relationship known as protocooperation occurs when the mutualist and host are not metabolically dependent on one another. It is described as a relationship in which the organisms involved benefit from one another while being independent of one another. The occurrence of protocooperation is not at all required. Without interaction, it is even conceivable to grow and survive. As a result, in protocooperation, interactions between organisms are only motivated by the benefits that they stand to earn from them. Example: ants and aphids.

Interesting Facts

  • In mutualism, both living beings benefit from each other’s company. This is a positive, friendly relationship.

  • In ectoparasites, the parasite lives on the body of the host. The parasite is referred to as an Ectoparasite. They are the causative agents of diseases but with low mortality.

  • In endoparasitism, the parasites are found inside the host's body. The parasite is referred to as an Endoparasite. They could be found in cells, blood or the gastrointestinal tract.

Important Questions

1. What is the function of an ecosystem?

Ans: Ecosystems support the biosphere and keep the planet's natural balance.

2. What is a parasite?

Ans: A parasite is a living thing that inhabits its host and feeds off of or at the expense of it.

Key Features

  • Predation is an essential ecological interaction as it plays a significant role in controlling population, distribution and species diversity in an ecological setting. A rise in predators drops the number of prey, which means that the predators fall short of food, ultimately leading to their extinction.

  • There are various types of ecological interactions. Competition is the contest or challenge between organisms for food, shelter, space, mates and other resources. Predation is when one organism hunts and feeds on another organism. Mutualism, commensalism, protocooperation and parasitism are types of symbiotic relationships. A close and ongoing relationship between organisms is called symbiosis.

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FAQs on What are the Types of Interactions Between Organisms?

1. What is ecology?

The study of the relationships between the biotic entities like microbes, plants, animals, birds, insects etc., and the abiotic entities like sunlight, water, temperature, minerals etc., in an environment is termed ecology. 

2. What distinguishes mutualism from commensalism in particular?

In mutualism, both living beings benefit from their association with one another. In commensalism, only one organism benefits from the other and not vice-versa.

3. Name the positive ecological interactions.

Mutualism and Commensalism.

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