Straight or smoothly curved filaments 1.5 μm in diameter and 100 to more than 500 μm in length are formed by rod-shaped cells with clear
septa growing within a long, tubular sheath. An adhesive basal element at one end of the filament can aid attachment to solid surfaces. The sheath offers some protection from predators, and the ability to anchor in flowing water allows access to a passing stream of food and nutrients. Individual mature cells swarm out of the protective tube to colonize new sites. Each motile mature cell has an intertwined bundle of
flagella appearing as a single flagellum consisting of a long filament with a short hook and a basal body complex, but it is distinguishable by
electron microscope as 10 to 30 strands with diameters of 12.5 to 16 nm each.
S. natans stores reserves of
poly- beta -hydroxybutyrate as internal
bioplastic globules making up 30 to 40% of the dry weight of a colony. ==Habitat==