Splitting from its ancestor species, bistage trisphourus adapted to the freshwater environment of the Yokto River and Marsh. Despite its green color, bistage trisphourus is a consumer, specifically targeting smaller cells, primarily single-cell plants. In evolving from its ancestor, bistage trisphourus only experienced two major changes, the first being the development of two stages, a single-cell free swimming form that sometimes gathers together and forms floating colonies up to one centimeter in diameter. The second major change is that the colony form will commonly exchange genetic material, sometimes with multiple partners, before dividing. Once a colony version of bistage trisphourus divides, one original cell remains in the colony while the other goes off as the free swimming form form.
While as the free swimming young form, bistage trisphourus uses its flagella for movement and consumes prey cells through its front end, much like its ancestor. However, the colony form simply drifts on the surface to the water, dangling its flagellum down, when a prey cell bumps into one of these flagellum, it is trapped as the flagellum coils around the prey and brings it back up to bistage trisphourus for consumption. Due to the success of both stages in capturing prey, it has driven ciliognathus to extinction, both by consuming it directly and by consuming its prey. Larger predatory cells, however, remain unaffected as they can consume the free swimming stage of bistage trisphourus.