LANSING, Mich. (WXMI) — Anglers and swimmers may spot freshwater jellyfish in Michigan’s lakes and rivers this summer.
The Michigan Department of Natural Resources says the jellyfish are not cause for concern, as they cannot harm humans and have very little negative impact on the environment.
Known scientifically as Craspedacusta sowerbyi, freshwater jellyfish are technically not jellyfish due to having velum, a membrane their marine cousins do not possess, the DNR explained.
We’re told freshwater jellyfish are likely native to Asia but have been prevalent in most of North America for more than 100 years.
Freshwater jellyfish are small, no larger than a quarter. They tend to become visible to the naked eye in late summer when polyps advance to the “medusa stage.”
"These are the sightings that often trigger calls to local DNR offices from curious spotters who have caught the rare glimpse of the invertebrate," Northern Lake Huron Manager Tim Cwalinski said. "Though freshwater jellyfish do have stinging cells like the marine species, their tiny size means they lack the ability to sting, and so they're not harmful to people. It is also believed to be unlikely that freshwater jellyfish could consume enough zooplankton in our bodies of water to negatively compete with fish species."
