Giant files: Nomura and Lion’s mane jellyfish

The Nomura Jellyfish

3084070830122111Nomura Jellyfish are a large species of Japanese jellyfish, that seems to be giving them some big headaches. They can grow up to 2 meters in diameter and usually weigh over 200 kilograms, going up to 220 in numerous cases and they spawn in the seas between China and Japan, invading the Japanese shores for 4 years now.

jellyfish_invasionSince then, they’ve become such a problem that a commitee has been formed just for them, and researchers have been trying to promote them as a novel food. Students in Obama, Fukui (Japan) have managed to turn them into a sort of tofu, and they also managed to extract colagen, which is beneficial for the skin.

jellyfish_nomStings are generally very painful, but do not cause major damage. Just 8 deaths have been caused by stings from the Nomura Jellyfish. So what caused this species to grow so large, even 100 times bigger than the average jellyfish? Scientists have been able to come up with a few theories, and there’s a big possibility that all these theories work together:

  • – China’s new dam, Three Gorges Dam on the Yangtze river is the biggest hydroelectric project. It also increased the amount of phosphorus and nitrogen in the waters off China, which is just what the Nomura jellyfish look for in a breeding ground.
  • – Also, it is possible that the waters have been enriched in nutrients due to the activity of farms.
  • – The third theory is again linked with Chinese activity, especially with the development of ports and harbours, which are structures the larvae attach themselves to.
  • – It could be that due to global warming the waters are heating and the waters are becoming more acidic, making it a better environment for jellyfish.
  • – The last theory is that China has overfished their waters and eliminated the predators that fed on the larvae


Even with the full help of the government, the Japanese have found it very hard to come to terms with these giants. Of course they aren’t immortal, but the problem is that whenever they feel under attack or threatened, they release billions of sperm or eggs which attach to corals or rocks and when conditions are favorable, they detach and grow into more jellyfish.

Lion’s mane jellyfish

177430711_fokyg-s-1Jellies have been around for almost 700 million years, making them older than the dinosaurs. They are very simple yet effective creatures, possessing no bones or cartilage, no blood and no heart and also no brain! As a matter of fact, they are made up of 95% water.


However, the Lion’s mane jellyfish may just be the longest animals in the world. In 1870, off the shores of Massachusetts Bay, locals found a washed up specimen that had a diameter of 2.3 meters and its tentacles were 36.5 meters long, longer than a blue whale!


The tentacles are covered with millions of stinging capsules contained within the cells from the tentacles. This jelly, like many others, is a predator and captures its prey with the venom from the capsules. The venom is very powerful and could be fatal to humans, but in most cases, it’s not. It also lives in very cold waters, even in the arctic areas, and cannot cope with warmer waters so don’t expect to meet them when you go swimming anytime soon.


Image source. Photographer: Tim Nicholson

They frequently grow over 2 meters in bell diameter and 30 meters in length, at the end of each summer. Fortunately, by that time, they are rather uncommon.

14 thoughts on “Giant files: Nomura and Lion’s mane jellyfish

  1. Rogerscott

    I’d appreciate more external
    links to this story.

    It’s extraordinary, if true.

    However, I’ve learned not to trust
    ‘photo’ images purveyed over
    the internet.

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  3. Emily 

    This species does occasionally occur in large swarms, largely thought to be due to storms and tides that concentrate individuals together. They are predators, eating zooplankton, small fish and moon jellyfish.

  4. Monty

    i dont quite understand how “global warming” has anything to do with it. when you boil water on the stove, it does not become acidic. nice try, media

  5. Nicola

    Mihai, you are just… american! Everything dangerous in this world is because China bla bla bla… Thanks God Iran does not have access to the Pacific or Atlantic Ocean, otherwhise it would be of course mentionned in your “article”…
    By the way, Wikipedia says:” A coldwater species, this jellyfish cannot cope with warmer waters. The jellyfish are pelagic
    for most of their lives but tend to settle in shallow, sheltered bays
    towards the end of their one-year lifespan. In the open ocean, lion’s
    mane jellyfish act as floating oases for certain species, such as shrimp, medusafish, butterfish, harvestfish, and juvenile prowfish, providing both a reliable source of food and protection from predators.”

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