A happy Saduria entomon feasting on a mussle
Saduria entomon is a benthic isopod crustacean of the family Chaetiliidae. It is distributed along the coasts of the Arctic Ocean and of the northern Pacific Ocean. It is also found in the brackish Baltic Sea, where it is considered a glacial relict. Moreover it is present in a number of North European lakes, including Ladoga, Vänern and Vättern. It has been introduced into the Black Sea.