Archive for the 'Jellies' Category

A Blue View: Jellies – Oceans Out of Balance

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 14, 2013: Jellies – Oceans Out of Balance

A Blue View podcastClick here to listen to John discuss how the rapid increase in jellyfish
populations has 
negatively impacted the health of our oceans. 

Beautiful, eye-catching, and otherworldly, jellyfish are dazzling creatures to look at, though not something you want to run into at the beach.

Not technically fish, jellies have drifted through our seas for more than 500 million years. They range in size from that of a pinhead to more than 8 feet in diameter, with tentacles 130 feet long. Most species have tentacles that sting, even when they become detached from the jelly’s body. And, as many a beach-goer can attest, those stinging cells can make for some less than pleasant experiences when our paths accidentally cross.

Related to sea anemones and corals, jellies have no heart, brain, blood, or bones, and are 95 percent water. Contrary to popular myths, jellies are not out to get you. As ocean drifters, they are carried along on ocean currents. But their vast numbers in certain places have made them a menace, and their unique ability to thrive in less-than-ideal conditions has scientists keeping a close eye on these fascinating creatures.

Jellies seem less susceptible to algae blooms, pollution, warming waters, and reduced oxygen levels, meaning that the more the environment deteriorates, the better it is for jellies. In an alarming phenomenon dubbed “jellification” by some scientists, jellies in some areas of the world are literally taking over the seas.

The role of jellies in the ocean ecosystem and whether or not their increasing numbers are displacing other ocean inhabitants are both matters of active debate in the marine science community. There are several reasons attributed to the rise of jelly populations. In addition to their ability to thrive in inhospitable conditions, jellies benefit when the fish, turtles, and other species that normally eat them are overfished. Then, as jellies eat zooplankton, fish eggs, larvae, and even fish, they further impact the food chain, perpetuating an imbalance that’s difficult to correct.

An overabundance of jellies isn’t good for tourism around the globe, particularly when they wash up on beaches. Depending upon the species, a jellyfish sting can cause anything from mild discomfort to severe pain and in rare cases, like the box jellies of Australia, even death. Jellies also affect fisheries—and fisherman—when they collide with nets, sometimes even killing the catch with their toxins. Jellies can also cause power outages and equipment damage at power plants by clogging cooling intakes.

Considered a delicacy in China, some see dining on these unique creatures as a creative and efficient way to control the jellyfish population. The European Union has embarked on an international research program to evaluate the spread of jellies in the Mediterranean and other regions and develop a coastal management strategy accordingly.

For all the issues that jellyfish blooms can cause, they are essential and active participants in the ocean ecosystem. They belong there. The best way you can keep bays and oceans healthy is to make smart choices at home. One important place to start is in your yard. Avoid overfertilizing your lawn and garden. Excess fertilizer washes into our waterways, reduces oxygen, and contributes to harmful algae blooms—conditions that are great for jellies but terrible for fish populations. You might even consider opening your mind to a new delicacy when jellies show up on a restaurant menu near you.


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


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 Updates – March 1

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!

Hairy Jellies!

These jellies get their name from the fringe of fine, hair-like tentacles that grace the bottom edge of their bell.

hairy jelly

The red dots also seen along the bell’s edge of a hairy jelly are its “eyespots.” These clusters of photo-sensitive cells can differentiate between light and dark.

Hair jellies are native to the shallow coastal waters of the north Pacific!

These jellies are currently behind-the-scenes in our jellies lab, but will be on exhibit soon!

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

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!

Sign up for AquaMail

Twitter Updates


Get every new post delivered to your Inbox.

Join 239 other followers