Colony (biology)

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In biology, a colony (from Latin colonia) refers to several individual organisms of the same species living closely together, usually for mutual benefit, such as stronger defences or the ability to attack bigger prey. Some insects (ants and honey bees, for example) live only in colonies. The Portuguese Man o' War is an example of a colony of four different polyp forms.

An electronic bacterial colony counter.

A colony of single-celled organisms is known as a colonial organism. Colonial organisms were probably the first step towards multicellular organisms via natural selection.^{[citation needed]} The difference between a multicellular organism and a colonial organism is that individual organisms from a colony can, if separated, survive on their own, while cells from a multicellular lifeform (e.g., cells from a brain) cannot. Volvox is an example for the border between these two states.

A bacterial colony (or colony of other microorganisms) is defined as a cluster of organisms growing on the surface of or within a solid medium, usually cultured from a single cell.^{[citation needed]} Because all organisms within the colony descend from a single ancestor, they are genetically identical (except for mutations which occur at a low, unavoidable frequency), thus this technique can be used to isolate genetically pure strains from a genetically mixed population.