Venice is facing an extraordinary invasion of a bizarre, cannibalistic jellyfish that scientists warn is threatening fish stocks and wreaking havoc across the city's fragile lagoon ecosystem. The strange marine creature – known as the warty comb jelly, or sea walnut – has exploded in number throughout the Venetian lagoon, clogging fishing nets and devouring the building blocks of marine life. The jellyfish, whose Latin name is Mnemiopsis leidyi, is infamous for its unsettling biology. Its anus appears only temporarily during defecation before vanishing again – and it is also known to eat its own offspring. Named for their vivid blue claws, the crabs tear into clams, mussels, prawns and other seafood, ripping apart fishing nets and causing millions of euros worth of damage.