When we think of jellyfish we often think of trips to the ocean. I remember a trip to Jamaica when I was young where I was stung by a jellyfish and had to go to the doctor. Jellyfish are common along saltwater beaches and may even disrupt swimming.
Freshwater jellyfish are not as well known however they are a real thing.
Where Do Freshwater Jellyfish Live?
Freshwater jellyfish (Craspedacusta sowerbyi) are sometimes referred to as peach blossom jellyfish and live in Kentucky lakes and ponds. They have been spotted in many of our popular sporting lakes such as Cave Run Lake, Kentucky Lake, Greenbo Lake, and Lake Cumberland. They have even been identified in the Ohio and Kentucky rivers.
Many farm ponds across the state have had sightings of freshwater jellyfish including one in Pendleton County where Fox Run EEC is located. Excuse me while I stop writing and go check my pond for jellyfish.
In fact, freshwater jellyfish are surprisingly spread out in many areas of the United States. You can see by the map that freshwater jellyfish are located in states throughout the country. They are even in unexpected dry states such as Nevada and Arizona and cold regions like the upper midwest and northeast.
A recent map by the USGS shows the wide range of freshwater jellyfish.
The United States Geological Service is actually tracking jellyfish because it is a non-indigenous aquatic species. The species Craspedacusta sowerbyi is considered an “exotic” species of jellyfish and originally comes from the Yangtze River valley in China. They are now widespread throughout the world.
They were probably spread by the sale of ornamental water plants and through the fish trade.
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What Do Freshwater Jellyfish Look Like?
Late summer and early fall are the best time to get a look at these small, bell-shaped jellyfish floating in calm warm waters. Bell-shaped jellyfish are called hydromedusa which makes me think of Medusa in Greek mythology. She was the one with snakes in her hair which do resemble jellyfish tentacles.
They are 5–25 mm (less than one inch) in diameter and are translucent with an off white, grey, or greenish shade. Typically, they have four long tentacles and between three and seven shorter tentacles in between each of the longer ones. The short ones are used for feeding and the longer tentacles for movement.
Shaped like a bell they have a manubrium (stomach structure) at the top of the bell. The manubrium has a mouth with four lips!
Quite small, freshwater jelly fish are about the size of a penny. Photo by Myriah Richerson USGS
Life Cycle
When we see the Craspedacusta sowerbyi and think jellyfish, we are only seeing one aspect of their life cycle. They spend much of their life as microscopic podocysts in a dormant or resting stage.
They reproduce both sexually and asexually depending on their life stage. In the mature “jellyfish” stage they reproduce sexually and produce eggs that grow into larvae. The larvae then metamorphose into polyps.
The polyps form colonies. The polyps can reproduce by budding (asexual) that develops into a hydromedusa. This does not happen every year.
The jellyfish stage only occurs sporadically and is referred to as a bloom. These blooms are weather dependent. They typically occur in late summer and fall when water temperatures reach 25 degrees Celsius or 77 degrees Fahrenheit.
C. sowrbyi are also sensitive to the minerals and pH of the water just like micro-organisms in our soil. Read our blog about soil fertility Pass The Test.
Combine your love of the natural world with your artistic nature and color jellyfish!
Habitat
Freshwater jellyfish prefer to live in shallow, slow-moving, or calm water. They are most common in lakes and ponds. However, they are very adaptable to fluctuating conditions.
They are predators and feed on any tiny organisms and zooplankton that comes within the reach of their tentacles. The tentacles contain a toxin that stuns the prey so the jellyfish can move it to the mouthparts.
Photo by Dave Head USGS
Danger To The Environment
At this point, Craspedacusta sowerbyi , are not considered a danger to the native environment. In fact, the Department of Fish and Wildlife does not monitor them at all. They do contain toxins in their tentacles for catching prey however, they are not large enough to penetrate human skin.
One study showed they occasionally eat some fish eggs but it is not considered enough to affect populations in ponds or lakes.
If you are interested in aquatic life check out our blog Turtles Are Terrific
Ame Vanorio is a former science and special education teacher and the director of Fox Run Environmental Education Center. She is a licensed wildlife rehabilitator and teaches classes locally and online about organic gardening, green building, living off-grid, and wildlife conservation. Ame lives off-grid on her Kentucky farm with a myriad of domestic and wild animals.
