Usually the members of a colony are genetically linked by common heredity. Sometimes, as in bryozoa, they are genetically identical clones, sometimes as in eusociality, they are members of an extended family. Sometimes, as with the Portuguese Man o' War, the members of the colony are joined together as one individual, which operates as a single unit.
Most of the colonies in the groups listed below build a common structure or nest. Sometimes they are linked only by their behaviour. The close integration of termites, ants, bees and wasps is called eusocial.