Freshwater Jellyfish: Who Knew!

Long, flowing tentacles dangling from soft-bodied umbrella-shaped jellyfish are a sight most people imagine seeing in an ocean. What if those massive tentacles were in our freshwater lakes, too?

They are. Don’t worry though, the jellyfish found in our lakes are not as big as most people might think.

In fact, freshwater jellyfish are not considered very rare with sightings being recorded worldwide. Recently, older studies regarding freshwater jellyfish have been re-appearing with new details added.

Freshwater jellyfish are assumed to be a native species to the Upper Yangtze River basin in China. However, due to migration aided by boats and aquatic life, these creatures have spread worldwide.

This jellyfish species spends its lifespan in two stages; one being the polyp, which looks similar to sea anemone, and the second stage being a medusa, which is the jellyfish appearance. The transportation of the species can take place during either stage resulting in the wide range of habitation areas they are found in today.

The reason this species is so rarely acknowledged may be due to the fact that they are rather small, making them a hard creature to spot amongst other aquatic life or debris found in the water. Freshwater jellyfish are usually found to range in size from the diameter of a dime to that of a quarter. On a clear summer day, you may see jellyfish making an appearance near the surface of the water. In this case, try to scoop one up. I promise they will not sting.

Although marine jellyfish are known for their long tentacles and hazardous shocks, the freshwater jellyfish are relatively harmless. While these translucent, little peanut-sized jellyfish do have the stinging cells, they are so small that they are not able to penetrate the human skin. Speaking from experience, the little creatures feel almost like a slightly slimy contact lens. Whether fish or other marine life are affected by them is still unknown.  

Growing up in the middle of the Great Lakes region, I have seen my fair share of freshwater organisms. As a child, I grew up catching common freshwater creatures like fish, frogs, toads, and turtles. However, I did not expect that my yearly adventure out on the lake scooping jellyfish into a bucket was not common among other children in Branch County.

This past summer and fall season was another great year for jellyfish spotting. To broaden the awareness of these little creatures, I brought in a few of the jellyfish for my biology classes at Albion to observe. Last fall, Dr. Abigail Cahill, a biology professor who has an interest in invertebrates, was able to share the experience with some of her classes.

“It was a very exciting experience to see a Michigan species that I had never seen before,” said  Cahill. “I loved getting to share it with my students — most of them had not seen freshwater jellies and did not know that they are a part of the local fauna.”

Cahill also shared her knowledge of how the freshwater jellies, Craspedacusta sowerbii, belong to the Hydrozoa taxonomic class, which is not the same group as the marine jellyfish most people know.

“We think of jellyfish as being marine animals — and most are — so this was unexpected and special,” said Cahill.

Although Cahill comments on how it would be interesting to use these creatures in some of her research, it is hard to find a good source of freshwater jellyfish near Albion. Knowing the lake I grew up around contained jellyfish, I decided to do some of my own research.

The trail of information led me to and into contact with Dr. Terry Peard, a retired science professor from Indiana University of Pennsylvania, has dedicated his time and research to that of the freshwater jellyfish species. While running the freshwater jellyfish site, he has spread his knowledge of this species to the media and research agencies and aquariums around the world.

Peard states how Michigan, Indiana, Pennsylvania and California are the states with the highest freshwater jellyfish sighting reports. The confirmation of Michigan being one of the states that holds the most sighted population of these creatures is not surprising considering the state is known for its many lakes.

“It seems that the availability of food along with water temperature is more important than the water quality. Granted, it is easier to see them in cleaner water,” states Peard.

Peard’s research and experience with this organism, as described in his writings, are quite different than my own experience. Although I have only spotted jellyfish in clear lakes with good water quality, Peard contradicts this with his reports of finding the species in polluted swamps and small ponds, along with pristine lakes.

“The only significant difference we found was in the concentration of chlorine,” said Peard.

Based off many experiments and data collection, Peard is able to describe how a body of freshwater without jellyfish often contains a higher chlorine concentration.  

With the mention of chlorine, and in consideration of this year’s Earth Day theme of plastics on April 2, pollution in lakes poses a threat to freshwater jellyfish.

Most people are aware of the use of everyday plastics from water bottles to shopping bags. Most, however, are unaware of the fact that plastics never fully degrade. Instead, plastics simply break down until they are microscopic and unseen by the naked eye. These microplastics are found in many sources including food, soaps, clothing and water. The organisms living in these polluted bodies of water cannot digest the plastic, and so as the smaller species intake it, so then does the next larger species. Thus, the microplastics make their way up the food chain.

Can you imagine trying to digest plastic? Well, the small microfibers of the clothes you wash and the soaps and creams you use every day are filled with them. The scary fact is that once the plastic enters the body of an organism, it can not be filtered out.

With freshwater jellyfish being such small and microscopic feeders, the chemicals leaching out of plastics, along with the microfibers themselves, could have a life-threatening impact. Although the research on the topic of freshwater jellyfish and plastics has not been carried out to the fullest extent, there are still ways to help prevent it.

The next time you are out on the lake, try and remember to look around for tiny jellyfish. And the next time you go to purchase a bottle of water or clothing made with materials other than cotton, try to consider the tiny creatures trying to survive in the lakes near you. To learn more about how to help prevent the life-threatening growth of plastics on our planet, visit the toolkit on

According to the sighting reports sent to Peard, the closest lakes to Albion that have been recorded as having jellyfish appearances are the following: Beadle Lake, near Battle Creek, Calhoun County, Beadle Lake Rd and I-94; Brace Lake (upper and lower), Marshall, Calhoun County, near I-69/Homer Rd.; Gilletts Lake, near Jackson and Michigan Center, Jackson County, I-94

To view more possible locations of freshwater jellyfish, please visit Peard’s site. If you happen to come across the species one day, please send in a sighting report to help keep the knowledge of these wonderful little species up to date.

Earth Day Information:

Freshwater Jellyfish Information:

Photos courtesy of Terry Peard

About Jessica Behrman 44 Articles
Jessica is a senior from Fremont, Indiana, with a goal of one day becoming a science writer. She loves the environment, anything dark chocolate and an adventurous story.


  1. Are you interested?
    I believe we saw fresh water jelly fish in our lake today. Although they were smaller than described here, they sure looked like them. Picked up one but its shape was lost in handling. Size wise, match head.

    I live in St. Helen, mi. 48656 on Lake St. Helen, Roscommon county. 248 561 1388.

  2. While scuba diving at White Star Quarry in Gibsonburg Ohio yesterday we saw a bunch of these jellyfish. It was a weird siting indeed.

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