MISSOURI — Jellyfish in the Show-Me state are more common than you think. The Craspedacusta sowerbyi is the freshwater jellyfish of Missouri and they’re found statewide.
How did the jellyfish get here?
The Missouri Department of Conservation (MDC) reports this species is native to eastern Asia, but can now be found worldwide in appropriate habitats.
This jellyfish has two life phases: the polyp form and the medusa form. The polyp is tiny and adheres to other objects like submerged plants or possibly animals, much like a barnacle or sea anemone. The polyps form buds that separate to become new individuals. Considering this, it’s possible the polyps were unknowingly transported on aquatic plants, in stock tanks, or even on the feet of migrating birds.
When can I see the jellies?
The polyps bloom into their medusa form, the typical free-swimming jellyfish shape, when surface waters reach about 80F. This typically only occurs between July and September. When they appear, it is usually in large clusters of bell-like bodies that pulsate with fringes of tentacles.
When fully grown, this jelly can have a diameter of up to 1 inch.
Where are the jellies found?
The MDC says these jellyfish cannot tolerate much of a current and usually occur in calm or standing waters like lakes, ponds, reservoirs, or standing pools next to flowing water.
There have been reports of freshwater jellyfish in the following Missouri lakes: Ozark, Stockton, Table Rock, Lake Pomme de Terre, and Lake Tom Sawyer.
An MDC employee recorded this video of the jellies floating near the surface of Lake Tom Sawyer.
Do they sting?
These jellyfish are capable of stinging and use their tentacles to eat microorganisms like zooplankton but they can’t penetrate human skin. The MDC says some people have reported itching or redness, but they’re so small most people don’t feel them at all.
Do they pose a threat like other invasive non-native species?
Though the freshwater jellyfish are not native to Missouri, according to the Missouri Department of Conservation, they seem to be harmless when it comes to the ecosystems they bloom in.