It is also found in the brackish Baltic Sea, where it is considered a glacial relict.

[4] Moreover, it is present in a number of North European lakes, including Ladoga, Vänern and Vättern.

The largest ones are found in the depths of the Gulf of Bothnia,[6] reaching a maximum length of nearly 9 cm (4 in).

[7] Most individuals die after reproduction, and the species might be functionally semelparous, but it is probably capable of iteroparity.

[7] Saduria entomon is a predator that feeds on other benthic animals, such as Monoporeia affinis.