Symbiotic

Symbiosis is a close and long-term biological interaction between two different biological organisms. The organisms, each termed a symbiont, may be of the same or of different species. In 1879, Heinrich Anton de Bary defined it as "the living together of unlike organisms". The term was subject to a century-long debate about whether it should specifically denote mutualism, as in lichens; biologists have now abandoned that restriction.

Symbiosis can be obligatory, which means that one or both of the symbionts entirely depend on each other for survival, or facultative (optional) when they can generally live independently.

Symbiosis is often classified into three types: mutualism, commensalism, and parasitism, though this classification is artificial. Mutualism is when both organisms benefit, commensalism is when one benefits but the other is unaffected, and parasitism is when one benefits while the other is harmed. These types of symbiosis can be further classified as either endosymbiosis (where one symbiont lives within the body of the other) or ectosymbiosis (where one symbiont lives on the body surface of the other).

History

The definition of symbiosis was a matter of debate for 130 years. In 1877, Albert Bernhard Frank used the term symbiosis to describe the mutualistic relationship in lichens. In 1879, the German mycologist Heinrich Anton de Bary defined it as "the living together of unlike organisms".

Types of Symbiosis

Mutualism

In mutualism, both organisms benefit. This type is often seen in pollination, where the plant benefits from the spread of pollen, and the pollinator benefits from nectar or pollen.

Commensalism

In commensalism, one organism benefits while the other is unaffected. An example is barnacles that grow on whales. The barnacles benefit from the constant movement of water, which brings food particles to them, while the whale is unaffected.

Parasitism

In parasitism, one organism benefits at the expense of the other. The parasite derives benefits by living either within or on the host organism, which is harmed by the interaction.

See also

• Coevolution
• Mutualism (biology)
• Parasitism
• Commensalism

References

Symbiotic Resources
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