Spiny waterfleas are small aquatic predators native to Eurasia. The first report of spiny waterfleas in North America was in Lake Ontario in 1982 and was introduced to the Great Lakes in ballast water from ocean-going ships. “Spiny” is a species of zooplankton – small animals that rely on water currents and wind to move long distances. They prefer large, deep, clear lakes, but can also be found in shallower waters.