Posts Tagged 'jellies'

The Annual Resurgence of Urban Jellies!

national aquarium animal expert update

In late summer and early fall, Baltimore visitors and downtown workers are often startled when they glance down into the harbor and see large pulsing Atlantic sea nettles!

national aquarium atlantic sea nettle

Photo via Flickr user KTSeery.

The Atlantic sea nettle (Chrysaora quinquecirrha) is a jellyfish species native to the western Atlantic and the tributaries of the Chesapeake Bay. If we ever had a Maryland State jellyfish, it would be the notorious Atlantic sea nettle. While it’s true that most jellyfish species do make their homes in the ocean and are unable to tolerate fresher, “brackish” waters, this sturdy species can actually thrive in it!

Their umbrella-like bell is about the size and shape of grapefruit half. Long stinging tentacles trail from the margin of the bell and are used to capture food which includes plankton, other jellies and small fish. These jellies pulse up and down the water column, day and night, in search of food. During moving tides and windless days, large numbers of nettles may gather near the water’s surface.

national aquarium atlantic sea nettle

This jelly was spotted in the harbor water right outside of the Aquarium!

Jelly species survive the cold winter in a sedentary, polyp stage attached to hard surfaces like oyster shells, rocks and pier pilings. These polyps resemble tiny sea anemones and capture microscopic plankton with stinging tentacles. In late spring and early summer, when water temperatures start to rise, each polyp will start to produce and release tiny free-swimming sea nettles.

Feeding on the Bay’s abundant supply of plankton these nettles grow and reproduce rapidly. A single sea nettle may release up to 45,000 eggs daily. By July and August, sea nettle populations continue to expand and push north into the upper Bay. By the end of summer and early fall, the lack of rain allows the waters of the Inner Harbor to become saltier. This is usually when Atlantic sea nettles start arriving in decent numbers into the Inner Harbor.

jellyfish in the inner harbor

Photo via The Baltimore Sun.

The abundance of good food in these deep harbor waters usually results in some fairly massive nettles! And, just as our downtown sea nettle show starts to attract attention, it will soon come to an abrupt end. As the water temperatures begin to drop, the nettles die off and/or start shrinking rapidly. Though the jellies quickly disappear, it’s exciting to know that millions of tiny Atlantic sea nettle polyps are scattered throughout the Bay waiting for the warming waters of spring to start the annual cycle all over again!

national aquarium expert jack cover

Adventures in Jellyfish Collecting

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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.”

jellies collecting trip 2013

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.

jellies collecting trip 2013

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.

jellies collecting trip 2013

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!

Jack Cover

Diane Rehm’s Environmental Outlook: Jellyfish And The Health Of The Ocean

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Earlier today, I spoke to NPR’s Diane Rehm about jellies and the impact that jellyfish population increases and expansion of some species’ geographic ranges are having on the health of our oceans.

Jack Cover at Diane Rehm show

With Bill Dennison and Diane Rehm at NPR.

Jellyfish first appeared around 560 million years ago (long before the time of dinosaurs). They’re 95 percent water, have no brains and no bones and no heart or blood, yet these gelatinous animals are among the worlds’ most resilient organisms.

The jellies simple body plan has remained relatively unchanged. But lately some scientists are concerned the animals are thriving too well – overrunning marine ecosystems, forcing nuclear power plants to shut down and filling the nets of commercial fisherman and shutting down fisheries around the world.

Some of the jellyfish species on exhibit here at the Aquarium.

Jellyfish species from top left (clockwise): blue blubber jelly, upside down jelly, spotted lagoon jelly, Leidy’s comb jelly

There are both ecological human-related issues causing an “explosion” of jellyfish populations around the world.

  • Over the years, climate change has raised the average temperature of the ocean. While this rise has negatively impacted organisms like coral, warm season jellies start breeding earlier and have longer active seasons.
  • Human activities, such as the over-fertilization of our lawns and farms, results in a runoff of excesses of nutrients into the Chesapeake Bay and ocean. This results in what’s known as an algal bloom. When the algae absorbs all of this nutrient run-off, it dies. Bacteria then feeds on the dead algae and removes all dissolved oxygen from the water – this process is called eutrophication and produces “dead zones.” Fish and crabs perish in these dead zones, but not the resilient jelly. Jellyfish can survive with low oxygen levels!
  • Jellyfish are opportunistic feeders. When food, like zooplankton, is abundant, they will grow rapidly and reproduce at a rapid rate. Excessively large jellyfish populations can out compete young fishes that also feed on zooplankton.
  • Some scientists speculate that the reproduction of jellyfish predators may also be giving jelly populations a boost. For example, all seven species of sea turtle will opportunistically feed on jellyfish when they are encountered. The largest species of sea turtle, the leatherback, feeds almost exclusively on jellies. Pacific populations of leatherbacks are currently at about 7 percent of their historic population levels. Human activities are the cause of sea turtle population declines. Overfishing has reduced fish populations that also feed on jellies.

To listen the full “Environmental Outlook” segment on Diane Rehm’s show, click here

Jack Cover

Animal Update – October 26

Between our Baltimore and Washington, DC, venues, more than 17,500 animals representing 900 species call the National Aquarium home. There are constant changes, additions, and more going on behind the scenes that our guests may not notice during their visit. We want to share these fun updates with our community so we’re bringing them to you in our weekly Animal Update posts!

Check our blog every Friday to find out what’s going on… here’s what’s new this week!

animal update

Juvenile Nautilus 

Several new small chambered nautilus have been added to the nautilus tank in our Sensing gallery. The larger, older nautilus was removed and placed in backup while the new ones undergo a quarantine period.

chambered nautilus

Chambered nautilus

Did you know the nautilus is considered to be a “living fossil”? This species has undergone little change in more than 400 million years! The nautilus dominated the ancient seas before the rise of fishes, and appeared about 265 million years before the first dinosaurs. In prehistoric times, there were about 10,000 different species of the nautilus, but only a few species survived to the present.

Moon Jellies!

Ten beautiful new moon jellies have been added to our Jellies gallery at National Aquarium, Washington DC.

moon jellies

These jellies were actually born at our Baltimore location! The moon jellies are our most prolific species, meaning they produce the most offspring. We are able to control culturing life-cycle stages through manual temperature manipulation at our jellies lab. Petri dishes covered in polyps (sedentary stage) of this species spend three weeks in a refrigerator.

juvenile jelly

Juvenile moon jelly

Be sure to check back every Friday to find out what’s happening!

Jelly Swarm Invades Pier 4

A new swarm of jellies has invaded the National Aquarium’s Baltimore venue… and they’re right over your head!

The Jelly Swarm is an original art installation in the Aquarium’s Pier 4 atrium, just outside the entrance to the Jellies Invasion: Oceans Out of Balance exhibit. Our Exhibits & Design team worked with Stephen Seigel, who created the jelly lights for Seattle’s Experience Music Project, to develop their design concept. They then went to Dillon Works for final design, fabrication, and installation of the piece, which was installed this week.

 

More than 600 individually painted jellies in seven different shapes and textures comprise the piece, made of vacuum-formed polycarbonate. Altogether, it weighs more than 1,000 pounds.

Here’s a description of the concept from the designers:

As guests approach the Pier 4 atrium they’re greeted by hundreds of translucent, iridescent jellies that sweep down through the space. Crossing the balcony to the stairs they walk under the swarm. The colors shift in the sunlight and the jellies move gently with the currents of air. Following the flow of the jellies, guests descend the stairs and come under the swarm. Soft colors and shadows animate the whole atrium.

This art installation was supported by a donation from an anonymous donor, and was inspired by the many qualities of jellies that intrigue us—their translucent beauty, graceful pulsing movements, otherworldliness, and massive numbers.

Come to the Aquarium soon to see both The Jelly Swarm and the real jellies in our exhibit!


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