Looking closely at one, it seems alien, not of this world.

We live in a tsunami of anthropogenic change. Humans are unsatisfied with the status quo. We were never content just making tools. We want to move life around. The list of introduced species in this country is long: city pigeon, kudzu, wild boar, emerald ash borer, privet, Amur honeysuckle, European starling, zebra mussel, English ivy, Asian carp.

USGS has it wrong

The United States Geological Survey (USGS) reports that freshwater jellyfish first appeared in Tennessee in 1999. This is wrong, off by 61 years. Tennessee joined the list in 1938.

A bloom of jellyfish was discovered in Knox County on July 15, 1938 in Andrew Jackson Lake (now called Dead Horse Lake), a privately owned body of water about 12 miles west of downtown Knoxville. Sara Betty Fowler collected six live jellyfish and delivered them to Edwin Powers, head of the zoology department at the University of Tennessee, for him to identify.

Harry McCann, custodian of the Knox County lake, reported at the time that 1938 had been the third year in a row that the jellyfish had appeared in the lake and that each occurrence had lasted about 45 days. At the end of each bloom they had “more or less suddenly disappeared.”

Predicting where the medusas will materialize next is still difficult. From time to time they make news in local papers because their appearance is such an odd story.

In September 1997 they were found in Mead’s Quarry Lake in South Knox County. A sampling was taken to Ijams Nature Center and TVA aquatic biologist Bob Terry was called in to identify the mysterious oddities. A story by Morgan Simmons about the jellies made the front page of the Knoxville News-Sentinel. “Delicate little beasts, but beautiful, and more fun to watch than a lava lamp,” said Terry at the time.  

The impact of adding freshwater jellyfish in our environs is arguably minor. Because of their Cheshire-like lifestyle of popping in and out of North American waterways their impact, at this point, seems benign. They are never in one place too long to cause a real problem and provide a little extra food for local aquatic turtles. The jellies are just an odd story, nothing like the 1876 introduction of kudzu. 

A mystery wrapped inside an enigma

Describing the intentions of Russia in 1939, Sir Winston Churchill said, “It’s a riddle, wrapped in a mystery, inside an enigma.” He could just have easily been talking about freshwater jellyfish. But unlike kudzu, freshwater jellyfish have the Cheshire Cat-like ability of appearing and disappearing. Here one year, gone the next.

There are arguably no direct impacts on native environments, but they are certainly worth a mention.

The tiny medusas were first identified and named when they mysteriously appeared in England. The Secretary of the Royal Botanical Society, William Sowerby, discovered the tiny free-swimming medusas in a tank devoted to the cultivation of imported water lilies. Baffled, he contacted and gave samples to Dr. George Allman, a zoology professor, and naturalist E. Ray Lankester. Both men rushed to publish an account of the unique lifeform. Lankester’s appeared first in the scientific journal Nature on June 17, 1880, only one week after the jellyfish were discovered. In it he gave a detailed description and proposed the Latin name Craspedacusta sowerbii, in honor of the jellyfish’s discoverer.

The small jellyfish appeared again, more than 20 years later in Lyons, France, in artificial tanks used to cultivate imported water lilies and again in a basin at a botanical garden in Munich, Germany in 1905.

In August 1907 the jellyfish popped up at a fourth location. A small bottle containing live medusas was sent to the office of Charles Hargitt at the Bureau of Fisheries, Woods Hole in Massachusetts. The jellyfish had been collected in a greenhouse aquarium in Washington, D.C.

The Washington medusas “disappeared as mysteriously as they came,” Hargitt reported, and “not a single specimen could be found where for weeks they had been abundant.”

The next recorded occurrence of freshwater jellyfish in North America was even more baffling. Early one morning, on September 27, 1916, a “large bottle of creek water” was brought to Harrison Garman at the University of Kentucky. The jellyfish had been found in Benson Creek near Frankfort, only twenty-five miles from Lexington.

By 1937, the jellyfish had found their way to 19 states, mostly in the east. They would appear and mysteriously disappear, turning up in lots of unusual places and poof; they were gone.