Jellyfish taking over oceans, experts warn

Karla Cripps, CNN
6 minute read
Updated 9:38 PM EST, Wed November 6, 2013
A 5-foot giant jellyfish recently washed up on a beach in Tasmania, an island off the southeast coast of Australia. Scientists are working to classify the new species. Click through the gallery to see more photos of jellyfish around the world.
A new species —
A 5-foot giant jellyfish recently washed up on a beach in Tasmania, an island off the southeast coast of Australia. Scientists are working to classify the new species. Click through the gallery to see more photos of jellyfish around the world.
JOSIE LIM/AFP/Getty Images
A West Coast sea nettle swims in the Aquarium of the Pacific complex in Long Beach, California. Sea Nettles are most common during fall and winter months on California and Oregon shores, and may be found from Mexico to British Columbia. They're known for having a distinctive golden brown bell, up to 30 centimeters in diameter. Contact with the tentacles can produce a painful sting.
West Coast sea nettle —
A West Coast sea nettle swims in the Aquarium of the Pacific complex in Long Beach, California. Sea Nettles are most common during fall and winter months on California and Oregon shores, and may be found from Mexico to British Columbia. They're known for having a distinctive golden brown bell, up to 30 centimeters in diameter. Contact with the tentacles can produce a painful sting.
GABRIEL BOUYS/AFP/Getty Images
These psychedelic jellyfish are part of a display at Beijing's Blue Zoo Aquarium. "Jellyfish occur in all marine waters from pole to pole and at all depths," says Dr. Lisa-Ann Gershwin, author of "Stung! On Jellyfish Blooms and the Future of the Ocean." Life threatening varieties are found from about 40 degrees north to 40 degrees south latitude.
Not their natural color —
These psychedelic jellyfish are part of a display at Beijing's Blue Zoo Aquarium. "Jellyfish occur in all marine waters from pole to pole and at all depths," says Dr. Lisa-Ann Gershwin, author of "Stung! On Jellyfish Blooms and the Future of the Ocean." Life threatening varieties are found from about 40 degrees north to 40 degrees south latitude.
FREDERIC J. BROWN/AFP/Getty Images
These moon jellyfish are illuminated by colored lights at the Beijing Aquarium, the largest in China. They also call these "common" jellyfish. They're found in all the world's oceans, making them a popular choice for aquariums.
"Turn off the lights, and we'll glow." —
These moon jellyfish are illuminated by colored lights at the Beijing Aquarium, the largest in China. They also call these "common" jellyfish. They're found in all the world's oceans, making them a popular choice for aquariums.
MARK RALSTON/AFP/GettyImages
A diver attaches a sensor to a large Nomura's jellyfish off the coast of Komatsu in Ishikawa prefecture, northern Japan. Large schools of these giant jellyfish, which have bodies ranging one to 1.5 meters in diameter, drift into Japanese waters in autumn and damage coastal fisheries.
"Am I getting hazard pay for this?" —
A diver attaches a sensor to a large Nomura's jellyfish off the coast of Komatsu in Ishikawa prefecture, northern Japan. Large schools of these giant jellyfish, which have bodies ranging one to 1.5 meters in diameter, drift into Japanese waters in autumn and damage coastal fisheries.
YOMIURI SHIMBUN/AFP/Getty Images
A lion's mane jellyfish swims near England's Farne Islands. This species is the largest of all jellyfish, and also one of the most dangerous, <a href="http://aquarium.org/exhibits/oregon-coast/animals/lion-s-mane-jellyfish" target="_blank" target="_blank">say scientists</a>. Lion's manes have thick masses of dangling tentacles covered with stinging cells called nematocytes.
Lion's mane —
A lion's mane jellyfish swims near England's Farne Islands. This species is the largest of all jellyfish, and also one of the most dangerous, say scientists. Lion's manes have thick masses of dangling tentacles covered with stinging cells called nematocytes.
Dan Kitwood/Getty Images
A Papuan -- or spotted -- jellyfish swims in a tank at the Sunshine Aquarium in Tokyo. According to <a href="http://education.nationalgeographic.com/education/media/white-spotted-jellies/?ar_a=1" target="_blank" target="_blank">National Geographic</a>, their venom is mild and doesn't pose a threat to human beings.
Papuan jellyfish —
A Papuan -- or spotted -- jellyfish swims in a tank at the Sunshine Aquarium in Tokyo. According to National Geographic, their venom is mild and doesn't pose a threat to human beings.
YOSHIKAZU TSUNO/AFP/Getty Images
Though most of us try to avoid jellyfish in the ocean, few dispute how cool they look at in a well-lit tank. These Pacific Sea nettle jellyfish are part of a display at the Shark Reef Aquarium at the Las Vegas Mandalay Bay Resort and Casino.
Pacific sea nettle —
Though most of us try to avoid jellyfish in the ocean, few dispute how cool they look at in a well-lit tank. These Pacific Sea nettle jellyfish are part of a display at the Shark Reef Aquarium at the Las Vegas Mandalay Bay Resort and Casino.
Ethan Miller/Getty Images
Driven by overfishing and climate change, the dramatic proliferation of jellyfish in oceans around the world is a sign of ecosystems out of kilter, warn experts. Venomous mauve stingers (pictured), or Pelagia noctiluca, were found in high numbers along the coast of Catalonia and Valencia in summer 2013.
Summer invadors —
Driven by overfishing and climate change, the dramatic proliferation of jellyfish in oceans around the world is a sign of ecosystems out of kilter, warn experts. Venomous mauve stingers (pictured), or Pelagia noctiluca, were found in high numbers along the coast of Catalonia and Valencia in summer 2013.
TARIK TINAZAY/AFP/Getty Images
This northern sea nettle is part of the jellyfish exhibition added to the SeaLife aquarium in Timmendorfer, Germany, earlier this year. Northern sea nettles, or chrysaora melanaster, are commonly found in the waters of the North Pacific.
Painful but pretty —
This northern sea nettle is part of the jellyfish exhibition added to the SeaLife aquarium in Timmendorfer, Germany, earlier this year. Northern sea nettles, or chrysaora melanaster, are commonly found in the waters of the North Pacific.
JENS BUTTNER/AFP/Getty Images
"Quite simply, most of us just don't like the thought of being stung by something slimy," says Dr. Gershwin. "There's the slime. There's the pain. So, more and more, places around the world that are suffering from jellyfish problems are developing prediction systems so that tourists can know when it is safe to swim."
Jellyfish and