Ecological Interactions | WWF
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Ecological Interactions

Premnas biaculeatus, Spinecheek anemonefish sheltering in its symbiotic anemone, Papua New Guinea.
An ecosystem has diverse living organisms. In the study of Ecology, these living organisms are categorized on the basis of the level of organization. So at the basic numbers level we have the population, then we identify the species and community to which that organism belongs, how it interacts with the ecosystem and other organisms in the ecosystem. Scientists have also studied the interaction between different organisms and classified their interactions into different types.
Explore the links given below to know how the smallest organism to the largest one is related to the environment around them.

Ecosystem: An introduction
Let us start with the basics first. We have to understand what an ecosystem is. What are the characteristics of an ecosystem? How do we distinguish between an ecosystem and a community? These are some of the fundamental questions answered by this site.

Ecological Terms
For a quick glossary of the terms used in ecology, visit this link. It includes simple explanations of the terms population, community, ecosystem, and biome among others.

For a more detailed look at the interrelationship between community, ecosystems and to get detailed descriptions of the terms used, visit this link.

Symbiosis: An example of ecological interrelationships
In most cases, the term symbiotic is used to define a relationship that is mutually beneficial to the involved parties. In Ecology, Symbiosis is a close ecological relationship between the individuals of two (or more) different species.

Sometimes a symbiotic relationship benefits both species, sometimes one species benefits at the other's expense, and in other cases neither species benefits. Ecologists use a different term for each type of symbiotic relationship. When both species benefit it is defined as Mutualism.

When one species benefits and the other is unaffected, it is defined as Commensalism. When one species benefits and the other is harmed it is defined as Parasitism. When neither species benefits it is defined as Competition. When one of the species is unaffected, it is defined as Neutralism. Symbiosis is fully explained in detail at this site.

Apart from the definition of the main term, the description has additional notes with examples of symbiotic relationships and related terms used. For more details and examples of different interrelationships visit this page.