Jumpin’ jellyfish! They do exist in our ponds

Just when I thought I had seen it all — from weeds to fish kills in freshwater ponds — a new oddity pops up.

When I first saw this strange new creature, I said to myself I must be dreaming.

It was a freshwater jellyfish.

This sighting prompted a call to Dr. Eugene Braig IV, program director, aquatic ecosystems with the Ohio State University Extension School of Environment and Natural Resources. Braig said that jellyfish are quite common in Ohio’s aquatic freshwater ponds across the state. However, we rarely see them.

Sea Grant Pennsylvania State University describes freshwater jellyfish as similar in appearance to its saltwater relative. The freshwater jellyfish is considered a member of the hydra family and not a “true” jellyfish. It is widespread around the world and has been in the United States since the early 1900’s. Even though this jellyfish uses stinging cells to capture prey, these stingers are too small to penetrate human skin and are not considered a threat to people. Their botanical name is Craspedacusta Sowerbyi.

Most likely they arrived in the United States from China Yangtze River valley in imported aquatic plants and fish. Since arriving, the jellyfish have spread by migratory waterfowl. Most of the time the jellyfish live in the bottom of a pond and are called a polyp.

About the size of a penny, jellyfish lack tentacles and feed on zooplankton in the water. When environmental conditions are right during the summer months and the pond has plentiful zooplankton, the polyp will transition to an adult called a medusa. Medusas are the size of a quarter and have tentacles that help with locomotion throughout the water column. When either water temperatures cool or zooplankton become less plentiful, the jellyfish change back to polyps and settle back to the bottom of the pond. Some ponds will only have a few jellyfish present, while other ponds may have thousands.

If this was not enough, another feature creature has made an appearance. This time they were Bryozoans, also known as moss animals. Bryozoans are large, globular, brown jelly-like growths that show up in Ohio’s ponds and lakes, usually attached to woody debris or docks. They can range in size from a baseball to as large as a basketball. Like jellyfish they are also spread by waterfowl.

These growths are hundreds to thousands of microscopic animals called zooids. The most common zooid botanical name is Pectinatella magnifica. The zooids grow in a unique rosette pattern and form a firm, slimy base which attaches to anything stationary below the surface of the water. The colony range in color from clear, to green, to a brown red; and resemble a slimy blob like brain. They feed on bacteria, algae and protozoa. They use nonstinging tentacles lined with microscopic hairs found at the end of its body to catch food particles and draw them towards their mouth. While feeding they filter the water helping to consume algae and remove suspended sediments. As temperatures cool in the fall they will disintegrate. Bryozoans in a pond is an indicator of a healthy ecosystem.

Like jellyfish, bryozoans are unique odd entities that live in our ponds. Though some people find them objectionable, they do not cause harm to our aquatic ecosystems. At this point in time, the Environmental Protection Agency has not registered any products for their control.

As part of our ecosystem, we need to adapt and live in awe with these fascinating oddities.