STORIES THE VIEW UPSTREAM By: Keith "Catfish" Sutton Ooey, Gooey Critters to Watch for When Fishing This Summer Seeing freshwater jellyfish and bryozoans make a day on the water extra special If you're lucky, you might see two strange-looking invertebrates ' freshwater jellyfish and bryozoans ' when fishing this summer. (Photo courtesy of Keith "Catfish" Sutton) We were fishing in a small west-Arkansas lake when we first saw them. My son Matt was sculling our johnboat from the front seat when he called out. “Holy smokes! What is that thing?” I moved forward and took a gander at the big gelatinous blob in the water that had caused his exclamation. “Looks like some kind of alien eggs, or maybe frog eggs” he said. “They’re weird for sure,” I said, reaching into the water and pulling the blob closer. “It’s not eggs, though – alien or amphibian. It’s a bryozoan.” This one was about the size of a softball, although I’ve seen some much larger. When I explained it was harmless, Matt held it up for a photograph. “That’s one of the strangest things I’ve ever seen while fishing,” he said. Soon, however, he would see something even stranger. “Here’s something else weird, Dad,” he said as we drifted across the lake. “What the heck are these?” Beneath the boat were dozens of little pulsating disks scattered about in the crystalline water. Each was about the size of penny or nickel and looked like a tiny parachute or umbrella. They were translucent and difficult to see in the clear water. I had come upon the same creatures once before in Lake Ouachita, just a few miles away. I was fishing with a friend when he pointed them out, slowly moving through the water below our boat. “They look like little jellyfish,” he said. “But we don’t have jellyfish in Arkansas, do we?” Turns out we do. Checking the internet that night, I learned that these unusual little creatures often appear in natural state waters during summer. It seems strange to find jellyfish so far away from the ocean. Yet these interesting animals are common in several of our lakes. I reached into the water beside Matt and cupped one of the parachutes in the palm of my hand. “What does it look like to you?” I asked. “It looks like the jellyfish we saw in the Gulf of Mexico – only smaller,” he replied. “That’s exactly what it is,” I said. “Only this jellyfish likes fresh water, not saltwater. Most people see them in summer when they’re out swimming or fishing or riding around in boats. Pretty cool, huh?” We watched in amazement as scores of the round jellies swarmed about us. And when we got home, we dug up more information I could share with you. Bryozoans There are about 50 species of freshwater bryozoans worldwide, but the one most commonly seen in U.S. waters is the magnificent bryozoan, Pectinatella magnifica, which often reaches a foot or two in size. The jelly-like masses often seen by fishermen are actually colonies of microscopic aquatic animals. They have been called everything from “moss animals” to “dragon boogers,” and are commonly mistaken for amphibian egg masses when seen floating in the water. Each mass consists of adjoining “rosettes,” each with 12 to 18 animals, around a central gelatinous mass that is 99 percent water. The colonies can be free floating but are usually attached to a branch or other submerged object. The individual creatures extend tiny tentacles from the edge of the blob to filter algae, their favorite food, from the water. The magnificent bryozoan was originally native to shady lakes and reservoirs east of the Mississippi. It has been introduced into Europe, Asia and Canada, however, and during the last 30 years has become established in freshwater systems in Texas, Oregon, Idaho, Washington and other western states. Warming due to climate change may allow them to spread even farther, something natural-resource managers would like to know about. You’re encouraged to report sightings in the western U.S. at USGS.gov. Freshwater Jellyfish The freshwater jellyfish originated in China’s Yangtze River. No one is sure when and how it spread from there, but the unusual little invertebrates probably were transported with ornamental aquatic plants such as water hyacinth from their native region in Asia. Freshwater jellies now live in waters on every continent except Antarctica. They were first found in the U.S. in 1880 and have since spread to every state except Montana, Wyoming, North Dakota, South Dakota, Alaska and Hawaii. Perhaps no other aquatic species on earth has spread so far and wide. This jellyfish has two life phases, each giving “birth” to the other. One form called the polyp is tiny and rarely noticed. It attaches itself to underwater surfaces much like a sea anemone in the ocean. Little buds form on their polyps’ sides and then separate to become new individuals. In this way, the polyps often form colonies containing numerous individuals. Much more likely to be seen are the free-swimming medusas. These have the rounded, concave shape of little umbrellas or parachutes. They are translucent, with a white, green, gray, tan or blue tint. Most are less than 1 inch in diameter. They have four long tentacles for swimming and many shorter ones for feeding. A fringe of up to 400 feeding tentacles may line the edges of the umbrella. Freshwater jellyfish eat zooplankton – microscopic animals that are common in Arkansas waters. They catch the plankton using those short stinging tentacles. As the jellyfish drifts, it waits for its prey to touch a tentacle. When contact is made, little stingers called nematocysts harpoon the prey. These inject poison that paralyzes the animal. The tentacle then coils around the prey and brings it into the mouth on the underside of the umbrella. The food is engulfed and will be digested. No one can predict for sure when adult jellyfish may show up in the places where they are found. They sometimes appear in a body of water in large numbers even though they were never reported there before. The following year they may be absent and may not reappear until several years later. It also is possible for the jellyfish to appear once in a body of water and never reappear. Sunny days in August and September, when the water is warm and food is abundant, are peak times to spot jellyfish. They will be floating or swimming gently just below the water’s surface. They are more easily seen if you’re wearing polarized sunglasses that reduce glare on the water’s surface. They often appear in large numbers called “blooms.” Some people worry that freshwater jellyfish may sting them. They do have stinging cells just like their saltwater relatives and, as mentioned, can use those stingers to paralyze the tiny aquatic animals they feed upon. But, fortunately, their stingers aren’t considered big enough to pierce human skin. There’s no need to worry about swimming or fishing in waters where freshwater jellies and bryozoans occur. Instead, enjoy your encounters with these fascinating creatures. Seeing them make a day on the water extra special.