Invasive species are very common around the world. The term refers to living beings (including plants) of all kinds that wind up in places they don’t belong. Sometimes they are somewhat benign, other times, like pythons, they are enormous problems. They succeed in adapting to their new home, often at the cost of native species.
Recently there has been news about fresh water jellyfish from China that appear to have colonised most of the United States. A fisherman in Minnesota has spotted hundreds of them in a lake. Apparently, the jellyfish have been spotted in 44 of the 50 United States. These were found and photographed in Lake Jane near the city of Lake Elmo.
The jellyfish in question is known as Hydromedusa. Hydromedusa actually refers to a family of jellyfish, about 800 strong, that live in bodies of water worldwide. The one found in Minnesota is native to the Yangtze River Valley. Like other jellyfish it uses stingers to paralyze small fish and eat them. They are small enough that their stingers can’t harm humans. So far, the jellyfish don’t appear to be causing environmental damage. They are quite tiny, some around the size of a quarter.
How did they get here? The best guess is that they came over in ornamental aquatic plants from China. Once here, they likely spread with stocked fish, aquatic plants or by waterfowl.
Invasive species in the United States include pythons, Joro spiders, Atlas moths, and giant African land snails. The United States Department of Agriculture has a list of invasive species in the United States.