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Jellyfish Gone Wild — Home
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Jellyfish Gone Wild — Text-only | Flash Special Report
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1. JELLYFISH JAM: In the Gulf of Mexico’s densest jellyfish swarms there are more jellyfish than there is water. More than one hundred jellyfish may jam each cubic meter of water. 
Scientists are currently pouring over records of worldwide marine life that were fastidiously maintained by some early explorers.  Such analyses will help scientists better define how and where human activities are promoting jellyfish swarms.

Credit: Monty Graham

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2. IMPACTS CASCADE THROUGHOUT THE FOOD CHAIN: A population explosion of comb jellies in the Caspian Sea is encouraging the growth of huge algae blooms, which appear in green on this satellite photo. The Caspian Sea, which is the world’s largest enclosed water body, is located between southeast Europe and western Asia.

Credit:  Jeff Schmaltz, MODIS Land Rapid Response Team, NASA GSFC

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3. JELLICIOUS MEALS FOR TURTLES:  Because leatherback turtles primarily eat jellyfish, these turtles provide important natural controls on jellyfish populations.  However, leatherback turtles are currently critically endangered because of various human activities, including the development of nesting beaches and the dumping of plastics into the ocean;  leatherback turtles sometimes mistake floating plastic bags for their jellyfish food, ingest the plastic and then suffocate.  The decline of turtle populations may promote jellyfish blooms.

Credit: Suzanne R. Livingstone, IUCN

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4. RINGING THE DINNER BELL: A jellyfish rings the dinner bell by closing its bell on a shrimp.  Filtering water to catch prey, a swarm of jellyfish may clear the entire water column of prey many times per day.

Credit: Rebecca J. Waggett, NRC Postdoctoral Research Associate

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5. A FULL MOON: Shown here is a moon jellyfish. Moon jellyfish were probably transported and introduced into many of their current worldwide habitats by ships. Scientists can distinguish native from invasive species via DNA analyses.  Native species that have had a long history in a particular ecosystem have had time to genetically mutate. Therefore, they carry more genetic diversity than non-native species that have recently been introduced into ecosystems by humans.

Credit: NOAA

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6. ALIEN INVASIONS: Fifteen to 25 percent of all marine species that are currently found in global sea ports are invasive. Large numbers of species of gelatinous animals have been introduced into non-native habitats by ships. Such invasions have wreaked havoc on many ecosystems, including the Black and Caspian Seas. The economic costs of such invasions have been staggering.
 
Caption: None Available. Stock image.

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7. STINGING OUTSIDE THE BOX: Large numbers of ultra-venomous box jellyfish (Carybdea alta) now regularly visit some beaches in Hawaii.  Their numbers substantially increased during the last 30 years.

Credit: Waikiki Aquarium

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8. STINGERS DOWN UNDER: Australia’s beaches regulaly host many types of toxic gelatinous animals, including the notorious Portuguese man-of-war and Chironex fleckeri, the world’s most venomous animal; a Chironex can kill a person in under three minutes. In addition, the potentially deadly Irukandji jellyfish, which are currently increasing in number, are small enough to slip through nets that protect Australia’s beaches from its larger Chironex cousins.

Credit: Dr. Jamie Seymour, James Cook University

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9. JELL HELL: During the summer of 2005, about 500 million Nomurai jellyfish--each weighing up to 450 pounds--floated into the Sea of Japan every day.  As a result, Japanese fishermen suffered tens of millions of dollars in losses.

Credit: Shin-ichi Uye, Hiroshima University

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10. A GIANT JELLYFISH: Each Nomurai jellyfish weighs up to 450 pounds and sports a bell up to seven feet in diameter.  Nomurai have recently increased in the Sea of Japan.

Credit: Shin-ichi Uye, Hiroshima University

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11. AN ALL-POINTS-BULLETIN FOR JELLYFISH POLPS:  Baby jellyfish live as fixed-position, stationary polyps before elongating and budding off into free-floating jellyfish.  Nomurai polyps are shown here.  Scientists suspect that huge swarms of Nomurai that have recently occurred in the Sea of Japan originated in China’s degraded coastal waters, which provide excellent polyp habitat. Much about jellyfish polyps--tiny, deep-dwelling and rarely found in the wild--remains unknown.

Credit: Shin-ichi Uye, Hiroshima University

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12. JELLYFISH IN TECHNICOLOR: Cotylorhiza tuberculata, or the fired egg jellyfish, is common to the Mediterranean, Aegean and Adriatic Seas.  The diameter of this jellyfish may exceed one foot, but it has only a mild sting, if at all.  Unlike many other jellyfish species, this species can cover distances on its own power without relying on currents.  This jellyfish is often accompanied by juvenile fish that take shelter in its tentacles.

Credit:  Alberto Romeo, romeofotosub team

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13. MAUVES  OF THE MEDITERRANEAN: The numbers of mauve stinger jellyfish (centre-right) in the Mediterranean have increased as populations of fish that compete for food with jellyfish have decreased.

Credit: Oceana

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14. AN EVER-INCREASING SPECIES COUNT: As scientists explore new ecosystems, they are identifying more species of jellyfish.

Credit: © Alberto Romeo, romeofotosub team

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15. A FAVORITE FOOD OF JELLYFISH: Copepods are small (microscopic to .25 inches), common crustaceans that collectively provide the biggest source of protein in the oceans.  These important creatures are among the favorite foods of jellyfish and jellyfish-like animals.

Credit: Matt Wilson/Jay Clark, NOAA NMFS AFSC

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16. JELLYFISH GEOMETRY:  Salps are tube-shaped gelatinous animals that live in every ocean. Increases in the Southern Ocean’s salp population, possibly caused by climate change, may eventually displace some important prey species of penguins and whales.

Credit: Laurence Madin, Woods Hole Oceanographic Institution