Archive for the 'Jellies' Category

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

Animal Updates – September 13

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!

Leidy’s comb jellies on exhibit! 

leidy's comb jelly

These amazing creatures can now be seen in  Jellies Invasion: Oceans out of Balance!

Did you know? Leidy’s comb jellies are bioluminescent, meaning they can make their own light (which they flash when disturbed).

leidy's comb jelly

This species looks different from other jellies because it’s not made up of a bell and tentacles. Instead, it is a translucent walnut-shaped body with wart-like bumps. For this reason, it’s sometimes called a sea walnut.

They make look “out-of-this-world,” but the natural range of this species is much closer than you think! They’re commonly found in the coastal waters of the Atlantic, from Cape Cod down to the Carolinas.

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

A Blue View: Surprising Sharks

A Blue View is a weekly perspective on the life aquatic, hosted by National Aquarium CEO John Racanelli.

From the smallest plants and animals invisible to the human eye to entire ecosystems, every living thing depends on and is intricately linked by water.

Tune in to 88.1 WYPR every Tuesday at 5:45 p.m. as John brings to the surface important issues and fascinating discoveries making waves in the world today.

August 28, 2013: Surprising Sharks

A Blue View podcastClick here to listen to John and aquarist Jackie Cooper
discuss the hundreds of species of lesser-known
sharks that inhabit our oceans! 

John Racanelli: In your mind’s eye, picture a shark for a moment. Perhaps it’s 9 or 10 feet long, with a mouth full of razor-sharp teeth and a menacing look. Now, take that mental image…and forget it. Today, we’re going to talk about the sharks that people seldom consider, the hundreds of species of smaller shark that inhabit every ocean on our planet. With me today is Jackie Cooper, our Senior Assistant Dive Safety Officer Aquarist at the National Aquarium. Thanks for joining me, Jackie!

Jackie Cooper: Thanks for giving me the opportunity to talk about something I’m so passionate about.

JR: How are these smaller species of shark like their larger counterparts?

JC: Well, all sharks are cartilaginous fish; they’re all carnivores; all sharks have 5 to 7 gill slits on the sides of their heads; all sharks have pectoral fins that are not fused to their heads. But that’s about where their similarities end. There is such a broad diversity of body shape and body size of sharks that is just amazing!

JR: What sizes are we talking about? 

JC: Well, the smallest shark is the dwarf lantern shark, which is only about 7.5 inches long. From there, they range up to the whale shark, which can be as large as 40 to 60 feet.

JR: So with these smaller sharks, it sounds like they really average to be relatively small compared to even humans. 

JC: Probably half of all the known shark species are 5.5 feet or smaller, and of that, half of the overall shark species numbers are shorter than 3 feet.

JR: Tell me a little bit more about those smaller sharks and their role in the food chain.

JC: We tend to think of sharks as apex predators, being at the top of the food chain. But in fact, most of these sharks are a part of the food chain. They’re similarly important, but they don’t sit at the top of it. Another thing that people tend to forget is that people eat shark meat much more than you would consider.

We tend to think of sharks as only being consumed in shark fin soup, but if you’re in Europe and you’ve had fish and chips, it’s more than likely you were really eating a shark called the spiny dogfish. They grow to be 3.5 to 4 feet long. The females don’t reach sexual maturity until they’re about 21 years old and produce only small litters. And yet, this species is fished commercially and sold as “fish and chips.” It’s simply devastating to that population.

JR: I know that’s an important species along the Mid-Atlantic shoreline, too. Can you even find some of these species of shark being sold as food in places like Baltimore? 

JC: Certainly. There are definitely grocery stores in the Baltimore metro area that sell shark. Sometimes under names that we would not necessarily recognize as shark.

JR: Why do you think it’s important to understand these smaller species of shark? 

JC: I think the most important reason is that they’re also being threatened. It’s important to keep in mind that when you think about conservation, it’s often driven by money and the glamour, and big species of shark are very exciting to think about and talk about and look at pictures of. These smaller sharks frequently aren’t as glamorous and don’t tend to draw the same kind of funding, so they’ve been much less studied.

JR: Well, I know they contribute to healthy marine ecosystems, too. They’re obviously vital to our ocean habitats, right? 

JC: Every spot in the food chain is critical to maintaining the entire chain in a healthy manner.

JR: Jackie, I want to thank you very much for coming in to talk to us. To learn more about some of the smaller species of shark that inhabit our waters and to see a live cam of the new Blacktip Reef exhibit, visit aqua.org/ablueview.

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Animal Update: August 23

animal update

New Australian white-spotted jellies are on exhibit! 

Named for the white spots distributed evenly across their bell, this larger species of jellyfish can grow to be approximately 20 inches wide!

national aquarium white spotted jellies

Photo via Flickr user KtSeery.

Like most jellies, the tips of their transparent appendages are filled with of stinging cells (considered only “mildy venomous,” these jellies don’t pose a threat to humans who come in contact with them).

As its common name suggests, the natural range of this species includes Australia and most of the Indo-Pacific. However, in more recent years, commercial fishers have found large numbers of this species in the Gulf of Mexico. Biologists are concerned that, as an invasive species, these jellies may the native marine species in that area.

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


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