A Norfolk high school senior makes startling discovery

By Katherine Kasacek

Craspedacusta sowerbii? No, it’s not a galactic spaceship of science fiction movies or a fantastical monster found in books. Think more along the lines of a mop-head or Medusa, or maybe an invertebrate of the cnidarians family.

In short, a jellyfish, a freshwater jellyfish. The cousins of those translucent blobs that dot the ocean shore at dusk have made their way to Tobey Pond in Norfolk.

No need to worry, though. A Portuguese man-of-war will not be swimming alongside your child next year. These jellyfish are about the size of a nickel and their sting is so insignificant it cannot penetrate human skin. It is also unlikely these anomalies will inhabit the waters of Tobey again next year.

Scientists say appearances of freshwater jellyfish are common, but sporadic. This species may occupy one spot one year and then disappear from that location for the next decade.

Interestingly, Craspedacusta sowerbii are not indigenous to North America. Scientists believe they originated in the Yangtze River in China. The Craspedacusta sowerbii is structured differently from marine jellyfish, so technically it’s not a jellyfish. The Tobey population is particularly unique because it includes both the male and female gender. In other waters on other continents, it is very rare to find male and female jellyfish inhabiting the same water.

The discovery of the freshwater jellyfish in Norfolk came about one Sunday afternoon when a friend and I were kayaking on Tobey Pond. While relaxing in the little cove of crayfish and lily pads, I spotted what seemed to be a jellyfish. Hollering to my friend to retrieve a bucket, I followed the jelly around in a circle, but lost it in the glare of the setting sun. We spent the next half hour failing to capture the animal, until finally, my friend triumphed. We showed the jellyfish to a few mesmerized beach-goers, but in the end, we let it go.

Later that week, my friend and I entered our first biology class of the new school year at Regional 7. By this time, we knew there was no mistake. It was, in fact, a jellyfish. We finally shared our discovery with our teacher near the end of class. “No, there are no freshwater jellyfish in Norfolk,” he said. “It must have been a sponge.” Another biology teacher agreed.

One and a half weeks later, with permission from the first selectwoman of Norfolk and absolute determination to prove our  teachers wrong, we set off for Tobey Pond with two kayaks and four jars . We came away with four jellyfish specimen and had seen at least a dozen.

The next morning, we arrived at school with two jellyfish apiece. Our teachers and fellow students were amazed. Sponges? Not quite.

Photo, top, of a jellyfish specimen, by Katherine Kasacek.