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Slide Show: Jellyfish Jamboree--Are They Set to Seize the Seas?

A new paper proposes that humans are making the oceans a very happy habitat for jellyfish. Here's a closer look

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HAPPY HABITAT

Much about the jellyfish life history is still unknown. In the early larval stage, known as polyps, jellyfish are suspected to prefer hard surfaces onto which they can attach. Increasing costal development, offshore rigs and other objects may be aiding population booms by giving the baby jellies a solid habitat, notes the NSF.....[ More ]

FREE RIDE

Jellies have hitched free rides all over the world, frequently traveling in the ballast water of ships. So when ocean water from faraway seas is dumped into, say, the Black Sea, where there is little native competition, invasive jellyfish can take over.....[ More ]

OVERFISHING

Overfishing , as it turns out, is great news for jellyfish, which are now finding oceans an even better place to live and multiply, the study says. Popular fish species, including anchovies and sardines, feast on the same fare as the jellyfish, so when the fish numbers dive, a bigger buffet opens up for the jellies.....[ More ]

CLIMATE CHANGE

Although they don't technically have brains (they have a "nerve net" instead), jellyfish are no dummies. Many of them prefer—and thrive in— warmer waters , which could mean a big jump in jelly populations with global warming, the paper's authors propose.....[ More ]

DEAD ZONES

After a large plankton bloom, the decaying organic matter sucks up much of the water's oxygen, turning the area into a eutrophic " dead zone ." These dead zones—so called because few organisms can survive in these conditions—now make up about 100,000 square miles of the world's oceans, according to the National Science Foundation (NSF).....[ More ]

SMART EATERS

Jellyfish feed mostly on zooplankton , which thrive in nutrient-rich waters (often attributed to excess fertilizer and sewage runoff). As food becomes abundant, so, too, can the jellyfish. When conditions are ideal, hundreds of thousands can flourish, resulting in a full-on jellyfish bloom, or "swarm." 

When faced with a food shortage, fish often become weak and perish, but starving jellyfish can simply shrink and return to healthy size once food becomes available again, explains the new report.....[ More ]

GELATINOUS MENACE

Jellyfish may elicit oohs and ahhs at aquariums , but out in the watery wild they can wreak rapid and serious bodily harm. The venomous sting of a box jellyfish known as the Chironex fleckeri can kill a person in three minutes.....[ More ]

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