Freshwater Jellyfish-Who Knew?
Several weeks ago a family of vacationers found some jellyfish in a small, eastern Manitoba lake. The discovery was considered so rare that it made a splash in the local media. Jellyfish in a LAKE, a cold, freshwater, local lake! Who knew?!
Of course, the media played it up as another reason to be scared. Another dangerous, new, invasive species. Watch out, Manitobans! Pollution, environmental disaster, global warming. etc., etc.
It turns out that a few observant biologists here had previously seen this species of jellyfish, Craspedacusta sowerbyi, in Manitoba. Its appearance here is unusual and unpredictable but not rare. There is nothing to be concerned about.
I must confess that my only experiences with jellyfish have been confined to seeing beaches closed in Australia because of lethal salt water varieties and warnings in Florida and California about bluebottles. So, the discovery turned into quite an educational moment for me.
Craspedacusta sowerbyi are so tiny and clear that they have probably gone unnoticed by most swimmers and boaters. They’re about the size of a quarter and so weak that the sting is harmful only to small fish and plankton.
Although Craspedacusta sowerbyi originated in China, they can now be found throughout the world, including almost all of Canada and the US. (According to Wikipedia, the only states with no reports are Montana, Wyoming, North Dakota, South Dakota, Alaska or Hawaii and the provinces of Alberta or Saskatchewan.)
What’s most interesting about them is how they got here, and evidently how they escaped China. They start out as tiny polyps, go dormant in the winter, and get transported as polyps from one fresh body of water to another by aquatic plants and animals. They likely hitchhiked to Manitoba as dormant podocysts via some unwary ducks or geese and then grew into jellyfish.
Freshwater jellyfish. Now I know. Look for them in a lake near you.