Yes, Michigan does have freshwater jellyfish; here’s what to know from the DNR

It’s summer in Michigan, and people flocking to lakes and other bodies of water around the state may see something we didn’t know we had: jellyfish.

The Michigan Department of Natural Resources released information this week warning people they might catch a glimpse of freshwater jellyfish.

According to the DNR, jellyfish are not considered harmful to humans and have little impact on the aquatic environment.

They are not native to Michigan or even North America, but are believed to be native to China and Asia, according to the DNR.

“However, this species has been found in most parts of North America for more than a century, is considered a harmless member of our aquatic communities, and is definitely of interest,” the DNR said. .

The first recorded jellyfish in Michigan was from the Huron River in 1933. They are now found in most lakes and streams in Michigan, typically in late summer or early fall.

Its lifecycle includes:

  • Jellyfish spend the winter in waters where podocysts rest.
  • When conditions become more favorable, the podocysts develop into polyps and continue their life cycle with asexual reproduction.
  • By the end of summer, the polyp grows to the medusa stage, which most closely resembles a free-swimming jellyfish.

“These sightings have led to calls to local DNR offices from curious observers who have caught a rare glimpse of an invertebrate,” said Tim Kwalinski, DNR’s northern Lake Huron manager. It often happens,” he said. “Although freshwater jellyfish have stinging cells like marine species, their small size means they do not have the ability to sting and therefore pose no harm to humans. It is considered unlikely that sufficient zooplankton can be consumed in waters that negatively compete with fish species.
“If you were able to observe medusa stages or colonies of freshwater jellyfish in our lakes or slow-flowing streams this year, consider yourself lucky and don’t panic. Understand that they are just invertebrates that have protected our waterways for a century.”

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