It's true there are jellyfish in Missouri but they're too small to harm people

Photo byJim Rathert via the Missouri Department of Conservation.

The freshwater jellyfish has two phases. The polyp phase is tiny and is not free-floating. It attaches to plants or the bottom of a lake. It forms buds on its sides, then separates and becomes new individuals to form colonies. They can be unnoticed since they’re so tiny and can tolerate different temperatures.

The medusa phase is free-swimming. It has the typical jellyfish form. It is umbrella-like and has a fringe of up to 400 tentacles lining the edge of the umbrella. In Missouri, this form occurs during mid to late summer when the surface water gets to about 80F.

The medusa phase, which is the actual jellyfish, is the most commonly seen phase near the surface of the water. When fully grown, it’s only around one-half to one inch in diameter according to the Missouri Department of Conservation.

In Missouri, people usually only see the medusa phase occurring between July and September. This phase has been found in 44 states and appears during the summers of certain years. It’s challenging for researchers to measure their populations.

Their stinging cells located on their tentacles are used for feeding but likely don't penetrate human skin. While few have reported redness or itching, most people don't feel them.

The jellyfish have been in the United States since 1888. The first one collected in Missouri was in 1930 from a quarry pit in St. Charles County, said Will Mabee, an aquatic animal researcher with the Department of Conservation. (Source.)

Living in Missouri, one wouldn't think a jellyfish could be in our lakes. When you hear the word, jellyfish, you typically think of a saltwater creature that stings. The warm waters at the Lake of the Ozarks will bring them to the surface and aren't harmful to people because they are so very small.

It's believed these jellyfish originated from Asia being transported by aquatic plants. Also, because they're considered non-evasive, this means they're not harming our ecosystem.

Thanks for reading.