Giant Jellyfish Prepare to Invade Japan

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Giant poisonous jellyfish are poised to assault Japanese waters, experts warn.

Reports of massive bloomings indicate that this season’s Nomura’s jellyfish spawn should be a big one. The good news is that there may not be a nation on Earth more psychologically prepared for the invasion of giant monsters.

Nomura’s jellyfish is one of the largest jellyfish species in the world. It can grow up to 6.5 feet (2 meters) wide and weigh as much as 440 pounds (200 kilograms). Its toxic stings are usually intended for unlucky fish, crustaceans or other small marine life, but it has also been known to harm fishermen and divers who come into contact with it.

The animals spawn off the Chinese coast, where conditions are particularly favorable for breeding. And this year, they’re breeding a lot. Numbers are expected to explode, possibly 100 times more than normal.

Jellyfish invasions have happened before. Reports of unusually large schools of the creatures seem to come every 40 years or so, but in recent years those invasions are coming more frequently. The last Nomura’s army to hit the Sea of Japan was as recent as 2005, where the animals wreaked havoc on the Japanese fishing fleets.

Very little is known about why the jellyfish spawn in such large numbers some years but not others, making it difficult to guess at why the invasions have been so frequent in recent decades. Biological oceanographer Shin-ichi Uye of Hiroshima University told National Geographic that while the outbreaks can be predicted, they can’t be controlled. They are like typhoons, he told them. Giant jellyfish typhoons.

What is known is that the jellyfish only devote their full energy to breeding when they are in poor health or injured. When they are in good health, they seem to spend all of their time feeding, and their reproductive organs remain immature. This leaves open the question: Are the massive spawnings an indication that something is wrong rather than well with the population, or with their environment?

Scientists speculate that another factor could be the decline of the jellyfish’s natural predators, like sea turtles and fish species which eat the jellyfish when they’re still young.

Regardless of the cause of the invasion, the biggest casualty of the jellyfish attack will assuredly be the Japanese fishing industry. Their huge jelly bodies damage fishing nets, and they poison the caught fish with their stings, spoiling entire catches.

Though despite the nefarious news, hopefully researchers will take the invasion as an opportunity to learn more about these mysterious, majestic creatures of which so little is known. That, or make another giant monster flick featuring oversized lazer-shooting jellyfish.

Source: National Geographic

Image Credit: Kyodo via AP, via National Geographic