BACTERIA AS MODULAR ORGANISMS

▪ Abstract The body plan of modular organisms is based on an indeterminate structure composed of iterated units or modules arrayed at various levels of complexity (such as leaves, twigs, and branches). Examples of modular organisms include plants and many sessile benthic invertebrates. In contrast, the body of unitary organisms is a determinate structure consisting usually of a strictly defined number of parts (such as legs or wings) established only during embryogenesis. Mobile animals are examples. Unlike that of unitary creatures, the form of a modular organism derives from a characteristic pattern of branching or budding of modules, which may remain attached or become separated to live physiologically independent lives as parts of a clone. Modular organisms tend to be sessile or passively mobile and, as genetic individuals, have the capacity for exponential increase in size. They do not necessarily undergo systemic senescence, and do not segregate somatic from germ line cells. It is argued here that b...