Outforia Quicktake: Key Takeaways
- Nomura Jellyfish are massive, with some weighing up to 441 lbs (200 kg) and having a bell diameter of 6.6 ft (2 m).
- Rapid growers, Nomura Jellyfish can expand from a few millimeters to full size in just six months.
- Warming ocean temperatures, increasing nutrients, and decreasing fish populations contribute to their population spike.
- These jellyfish negatively impact Japan’s fisheries and their overabundance is a concern for the ecosystem.
- Some Japanese researchers are trying to promote the consumption of jellyfish to help combat their overpopulation.
Nomura’s jellyfish are some of the biggest jellyfish in the world, with some weighing up to 441 lbs (200 kg). They live around the waters of Japan where they appear in large groups called “smacks.”
Although these jellyfish are fascinating, they are causing some real problems.
Increased nutrients and warming ocean temperatures are causing their populations to spike. They are also depleting the eggs of their few natural predators. And Japan’s fisheries are beginning to feel the effects.
Keep reading to learn some fascinating facts about these ginormous jellies. We’ll also cover some interesting questions, like, are jellyfish edible?
What Is A Jellyfish?
Jellyfish are not fish, despite what their name suggests. Rather, jellyfish are a type of invertebrate called a “cnidarian.” They have dome-shaped bodies called “bells,” and long, flowing tentacles beneath them.
Jellyfish are close relatives of corals, sea whips, sea anemones, and hydrozoans. All these creatures are cnidarians, meaning they have stinging cells called “cnidocytes.”
The cnidocytes live inside the jellyfish’s tentacles. They discharge when something brushes against the tentacles. Before firing, cnidocytes live within a sac called a “nematocyst.”
“True jellyfish” belong to the phylum cnidaria and have stinging cells. There are other animals called “jellies.” They are not part of the phylum cnidaria, but look like jellyfish. Some of these animals include the Portuguese man o’ war and comb jellies.
What Are Nomura’s Jellyfish?
Nomura’s jellyfish (Nemopilema Nomura’si) is a type of large Japanese jellyfish. Their bell grows to about 6.6 ft (2 m) in diameter, and they can weigh up to 441 lbs (200 kg). Some of the largest individuals can grow 100 times larger than the size of an average jellyfish.
Nomura’s jellyfish are rapid growers. Medusa Nomura’s begin at only a few millimeters in length. In only six months, they can grow to full size.
Nomura’s jellyfish stings are generally painful but non-fatal. Still, China reported a few deaths from Nomura’s jellyfish stings.
Those who have been stung report a very intense pain upon stinging. Along with the pain comes burning. The location of the sting tends to become red and form blisters.
These jellyfish are most common across the northern East China, Yellow, and Bahai Seas. Some populations also live further north in the Sea of Japan. The Tsushima currents push them northward to the Sea of Japan.
Nomura’s jellyfish were not very common in these waters until around 2001. Fishermen only caught one or two jellyfish in their nets each week. Today, these jellyfish have become a much larger problem.
These jellies mostly eat tiny zooplankton, but larger individuals sometimes eat fish.
Nomura’s jellyfish have few natural predators. Leatherback sea turtles, swordfish, and tuna are their primary predators.
The reproduction of jellyfish occurs in several stages.
An adult jellyfish is a medusa, and they have the umbrella-like shape we’re all familiar with. Adults spawn during mass events, releasing billions of eggs and sperm into the water.
Fertilized eggs become planula larvae after only one day. Planula larvae are free-swimming animals with cilia that resemble a flattened pear.
The larvae swims for about four to eight days before they find a suitable place to settle.
Upon finding a spot, they become white and dome-shaped, becoming fixed polyps. The jellyfish become fully-developed polyps after about 10 to 20 days. They use their long, flowing tentacles to feed on microscopic zooplankton.
Polyps reproduce asexually by producing podocysts. A single polyp may produce as many as 18 podocysts between seven days and three months of age.
Within six months, an entire Scyphistoma colony forms. They come from podocysts from the original Scyphistoma. A colony only forms when the water temperature is around 64.4°F (18°C).
The Scyphistoma continue to develop and become strobila after only a day.
After five to seven days, the strobila develops into a free-swimming ephyra. Ephyra develop in early summer.
After 40 to 50 days, the creature finally becomes young medusae. Full-grown medusae spend most of their time reproducing. They have incredibly short lives and typically die over winter. Most have a lifespan of less than one year.
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Nomura’s Jellyfish Invasion
A Nomura’s jellyfish bloom is an increasingly common occurrence in Japanese waters. The shift in climate is causing jellyfish numbers to increase across coastal waters.
The most significant increase is that of the Nomura’s jellyfish. These giant creatures have been devastating fisheries in the Sea of Japan. They threaten the livelihoods of fishers across China, Japan, and Korea.
Decreasing Available Food
The primary food source for Nomura’s jellyfish is zooplankton. Zooplankton are microscopic organisms that float through the water. Due to the sheer number of zooplankton Nomura’s eat, there isn’t much left for other nearby organisms.
Nomura’s jellyfish eat fish eggs, too, and they have ferocious appetites. This further limits the number of fish in the ocean which can keep the jellyfish numbers down.
Usually, jellyfish populations aren’t a problem. The fish eat them, which keeps the numbers down. Yet, overfishing has led to a decrease in fish numbers.
Warming Ocean Temperatures
Plus, the shift in climate is beneficial to jellyfish. The warmer waters support their development, leading to even more jellyfish.
They can also handle harsh conditions produced by a warming climate that fish cannot. They can handle harsh levels of hypoxia — a deficiency of oxygen in the environment. Most fish are ill-suited for low levels of oxygen.
Researchers fear that Nomura’s jellyfish populations may completely decimate fisheries. The ocean continues to warm each year. The warmer waters are better for jellyfish, but terrible for most other animals.
A warming climate isn’t the only reason Nomura’s jellyfish populations are booming. More nutrients have been going into the surrounding waters, and humans are to blame.
There is a large dam in China named the Three Gorges Dam that sits on the Yangtze River. It is a massive hydroelectric dam. It has increased the amount of phosphorous and nitrogen in the waters off the shores of China. The increased nutrients make the perfect breeding grounds for Nomura’s jellyfish.
Researchers also theorize that farms have caused excess nutrients.
On top of that, jellyfish are rapid breeders. A single adult jellyfish can produce billions of eggs at a time. They release eggs and sperm whenever they feel threatened. The eggs attach to rocks and coral, developing into new jellyfish.
China has developed more ports and harbors along its coasts. Ports and harbors are ideal homes for jellyfish larvae. They attach themselves to the wood to become polyps.
Researchers have been trying to push Nomura’s jellyfish as food. They hope it will help with the overabundance of jellyfish.
Unfortunately, most people don’t like their texture, so they aren’t a huge food item.
Yet, students from Obama, Fukui (Japan) have created a tofu-like food from the jellyfish. They’ve also found a way to extract collagen from the jellies, which is very beneficial to the skin.
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Nomura’s Jellyfish Ice Cream
One product that has been developed using Nomura’s jellyfish is ice cream.
For the past three years, Tango Jersey Dairy, a coastal firm, has been producing 2,000 to 3,000 cartons of vanilla and jellyfish ice cream. To minimize its smell, the jellyfish is soaked in milk overnight before being diced.
While Nomura’s jellyfish ice cream is not yet widely available, some specialty shops in Japan have begun to offer it as a novelty item.
It is important to note that while Nomura’s jellyfish ice cream may be an intriguing novelty item, there is currently limited scientific research on the safety and potential health effects of consuming jellyfish in this form.
As with any new food product, consumers should exercise caution and consult with a medical professional if they have any concerns.
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Do People Eat Jellyfish?
Nomura’s jellyfish are edible, but it’s rare for people to consume them. Locals consider Nomura’s jellyfish a low-quality food. Most jellyfish species have a desirable crunchy texture. However, Nomura’s jellyfish aren’t crunchy.
How Do You Eat A Jellyfish?
Cooked jellyfish tend to have a crunchy texture. You can eat it shredded or sliced. Some chefs cook it with sugar, oil, vinegar, or soy sauce.
Some enjoy eating it over salad. Others enjoy eating it like boiled noodles served alongside meat and vegetables.
Can You Touch A Jellyfish Without Getting Stung?
The only part of a jellyfish that will sting is its tentacles. So, you can touch the bell of a jellyfish without worrying about stings. In fact, there are some aquariums that have jellyfish touch tanks.
Are There Jellyfish That Don’t Sting?
There are many kinds of jellyfish that produce very mild stings, or do not sting at all.
Here are some jellyfish that are harmless to humans:
Moon jellies (Aurelia aurita)
Sea gooseberries (Pleurobrachia bachei)
Crystal jellies (Aequorea forskalea)
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