The world--and especially the world's oceans--are full of strange animals, but the weirdest may be the Nomura jellyfish. It can measure up to 6 feet in diameter and weigh more than 450 pounds. Half a dozen can break fishing lines and give a Japanese fisherman a fit. About four years ago, the giant jellyfish started to gain notice when fishermen, fishing the Sea of Japan for anchovies, salmon and yellowtail, were instead catching these sea monsters in their massive fishing nets. Now the jellyfish are again gathering in the Yellow Sea off China and the Korean peninsula. It is expected to drift into the Sea of Japan in the next few months.
Last time the situation got so bad, the salmon boats in northern Japan stopped going out, and it's reported that in some places fishermen lost 80 percent of their income. The nuclear power plants along the Japan Sea coast even sucked the jellyfish into their water pumps used to cool the reactors.
The giant jellyfish's proliferation is a mystery but some have theories. Discovery News reports:
Anthony Richardson of CSIRO Marine & Atmospheric Research and colleagues reported their findings in the journal Trends in Ecology and Evolution to coincide with World Oceans Day.
They say climate change could also cause jellyfish populations to grow. The team believes that for the first time, water conditions could lead to what they call a "jellyfish stable state," in which jellyfish rule the oceans.
The combination of overfishing and high levels of nutrients in the water has been linked to jellyfish blooms. Nitrogen and phosphorous in run-off cause red phytoplankton blooms, which create low-oxygen dead zones where jellyfish survive, but fish can't, researchers said.
More on Giant Creatures:
Animals of the Ocean, In Particular the Giant Squid
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80+ Whales and Dolphin Beached in Australia