Adventures in Jellyfish Collecting
Published September 24, 2013
When planning what species to display in Jellies Invasion: Oceans out of Balance, we knew it would be important to include species found in local waters. To keep our exhibits full of jellies, National Aquarium staff venture out to the Chesapeake Bay throughout the year to collect the following local species: Atlantic sea nettles (Chrysaora quinquecirrha), Leidy’s comb jellies (Mnemiopis leidyi) and Lion’s mane jellies (Cyanea capillata).
Our most frequented spot for jellyfish collecting is on the Eastern Bay, off the southeast end of Kent Island. This past weekend, we launched from my family’s waterfront property located in the southeastern region of the island. My nephew, Joe Cover, Jr., a resident of Kent Island and an avid fisherman, is my unofficial jellyfish monitor/assistant. He keeps me posted on when and where he is seeing groups of jellies.
Ideal jelly-collecting conditions include a moving tide (to raise jellies to the water's surface), little to no wind and a cloudless sky (the mostly transparent Leidy's comb jelly is almost impossible to spot when the sky is overcast). There are times when you believe the conditions are ideal, yet few or no jellies are found at the surface. When this happens, my standard line is, “You know, we have just been outsmarted by an animal that has no brain.”
We were glad to see calm waters and no clouds this past Saturday!
Equipped with collecting bags, five-gallon buckets, glass beakers and special plastic jelly-collecting nets, we motored out to the middle of Eastern Bay. The water was a bit choppy, but I stopped the boat as soon as I saw a “slick,” a narrow band or area of still water among the light waves. Natural slicks are sometimes formed when concentrations of microscopic diatoms gather at the surface and release natural oils that change the surface water’s density and retard the formation of ripples and small waves.
As we slowly drifted along with the wind and tide, we started to see Atlantic sea nettles and large Leidy’s comb jellies (a whopping 3 to 4 inches long) pulsing along the surface. We were in the right place at the right time! Upon further examination of the water's surface, we saw thousands of tiny copepods (zooplankton) gathered - another great sign! Jellies continued to surface to feed on the copepods and, in some cases, each other. Yes, some jellyfish (like Atlantic sea nettles) include other jelly species (Leidy's combs) in their diets.
I started filling collecting bags placed in five-gallon buckets with Bay water.
Jellyfish have no bones and little body structure. In fact, 96 percent of a jellyfish's body is water! A delicate jelly can easily be injured if it is removed from the water or rubs against any abrasive surface. To avoid injuring our specimens, we used smooth-sided beakers to corral the jellies. The jelly is then moved, in water, to one of the water-filled plastic bags in a bucket. The beaker is submersed into the bucket and tilted to gently release the jelly.
Care must be taken to prevent the creation of air bubbles, which can get trapped in the jelly's tissues and injure it. This is why beakers containing jellies are not poured in from above the water’s surface. Leidy’s comb jellies are especially fragile and must be transported with extra care.
In addition to their delicate body structures, quick temperature changes can be detrimental to jellyfish. It was relatively cool on this sunny afternoon, and the water in the buckets was staying close to the temperature of the Bay water. In a relatively short period of time, we filled six five-gallon buckets to capacity with jellies.
We headed back to the dock to prepare the buckets for transport to the Aquarium's Jellies Lab. Prior to loading the buckets into the car, air is removed from each bag, which is then sealed with a rubber band. After loading up the car, I headed back over the Bay Bridge to the Aquarium. The car’s air-conditioning kept the jellies at their preferred temperature.
Once at the lab, the buckets of jellies are unloaded and the rubber bands are removed to allow gas exchange to the water.
The final leg of the jelly-collecting process is to slowly acclimate these jellies to the water in an exhibit or holding tank. I hand this part of the journey off to the Jellies staff. All incoming jellies need to be slowly acclimated to both the temperature and the salinity of our exhibit water. This process can take several hours or several days depending on how the salinity of the Bay and our exhibit waters compare.
Jellyfish continue to fascinate and amaze our visitors. We're glad to provide our jellyfish gallery as a wonderful resource to connect people with our local jellies!