Nomura's Jellyfish - Giant Jellyfish invade Japan

Giant jellyfish descend on the Sea of Japan, causing untold devastation to coastal villages and leaving a trail of destruction and human misery behind.

Sounds like a great sci-fi flick. But it's not.

It's real and a nightmare for Japanese fishermen.

The massive sea creatures, called Nomura's jellyfish, can grow 6 feet (1.83 meters) in diameter and weigh more than 450 pounds (204 kilos). Scientists think they originate in the Yellow Sea and in Chinese waters. For the third year since 2005, ocean currents are transporting them into the Sea of Japan.

Spectacular, perhaps, to scientists, but perilous to villagers along the Japanese coast who have seen the destructive habits of these colossal creatures in the past. They had giant-jellyfish invasions in 2005 and 2007, and because they've recently been spotted in the Sea of Japan, they're bracing for another, potentially harmful wave this summer.

The jellyfish destroy fishermen's nets, getting trapped in them, tearing holes and ruining catches.

Fishermen often use expensive mazelike nets that stretch for hundreds of kilometers. When swarms of giant jellyfish tear them, the result is devastating.