Plancomycetes are obligately aerobic aquatic bacteria [requires atmospheric oxygen for growth] and are found in field samples of brackish and marine as well as freshwater samples. They reproduce by budding. In structure, the organisms of this group are ovoid and have a holdfast at the nonreproductive end that helps them to attach to each other during budding, called the stalk.

The organisms belonging to this group lack murein in their cell wall Murein is an important heteropolymer present in most bacterial cell walls that serves as a protective component in the cell wall skeleton. Instead their walls are made up of glycoprotein rich in glutamate. RNA sequencing shows that the plancomycetes are distantly related to the eubacteria.

The life cycle involves alternation between sessile cells and flagellated swarmer cells. The sessile cells bud to form the flagellated swarmer cells which swim for a while before settling down to attach and begin reproduction.