By Sid PerkinsYou wouldn’t want this creature as a parent. An invasive species of jellyfishlike animal in the Baltic Sea may survive harsh winters by consuming large numbers of its larvae, new research suggests.Mnemiopsis leidyi—commonly known as the sea walnut (above), because of its shape—is native to the western North Atlantic Ocean.
But it has proliferated in European waters in recent decades, likely after hitching rides in the ballast waters of cargo ships.
In the western parts of the Baltic Sea, the species’ end-of-the-summer population booms ravage the base of the marine food web, including fish eggs, fish larvae, and small crustaceans.