Septaria (gastropod)

Septaria is a genus of freshwater and brackish water snails, gastropod mollusks in the family Neritidae. These superficially limpet-like snails are native to the Indo-Pacific region. Most species are found in rivers and streams, mainly fast-flowing, but two (S. livida and S. tesselata; sometimes in their own subgenus Navicella) live in brackish coastal waters and the lower tidal section of rivers and streams. Their eggs are attached to hard surfaces such as stones. After hatching, many veligers avoid being swept away by the current by swimming close to the bottom, but it is speculated that some flow downstream into the sea only to return to freshwater later. The shell length of these snails is up to 3.3 cm (1.3 in), but there are some size variations depending on exact species.