Convoluta convoluta

Convoluta convoluta, also known as the acoellous turbellarian flatworm, is a small acoel in the family Convolutidae. Native to the Baltic Sea, it invaded the Gulf of Maine in the late 1990s.

Diet and symbiosis
This flatworm consumes juvenile settling mussels and harpacticoid copepods. It also engages in a symbiosis with a diatom of the genus Lichmophora, which has also invaded the Gulf of Maine.

Impact and ecology in the Gulf of Maine
In the Gulf of Maine, the impact of this species appears minimal as the habitat is presumably saturated with food, and the species is ultimately self-limited by species competition. It also appears limited to wave-protected habitats, where it prefers filamentous algae. In 2001, it occurred in densities of up to 19 per square centimeter.