Now that jellyfish can be up to 90% of the animal life in the Black Sea, it's worth asking why? Did the bad jellyfish kill off all the nice fish?
A new study says overfishing is to blame, by removing the fish and letting jellyfish take over the ecosystem.
"Initially, the jellyfish was blamed for the fish stock collapse," said Georgi Daskalov, from the UK's Centre for Environment, Fisheries and Aquaculture Science (Cefas). Now they believe that overfishing was the reason for the jellyfish boom.
This is not the first example of overfishing leading to jellyfish booms. Looks like Jeremy Jackson was right when he predicted the rise of slime.