Cercopagis pengoi

The 'fish-hook waterflea' Cercopagis pengoi is a zooplanktonic predator with great potential to alter pelagic food webs. 

Discovered in Lake Ontario in 1998, it is one of many Ponto-Caspian species that have been introduced by ships to the Great Lakes in recent decades (Ricciardi & MacIsaac 2000; Ricciardi 2006).