The Atlantic ctenophore Mnemiopsis leidyi is considered one of most harmful aquatic invasive species in Europe.
This comb jelly, native to the western Atlantic, was introduced into the Black Sea
in the 1980s and has spread to the Mediterranean and Caspian.
The invasion caused a catastrophic decline in zooplankton and pelagic fisheries.
The anchovy fishery in the region has had losses estimated in the hundreds of millions of US dollars per year.
Fish and invertebrate diversity is at serious risk from this small but abundant invader.