Jellyfish are the most inconspicuous creatures in the ocean. This "inconspicuous" is in every sense. Aside from admiring their graceful gestures in aquariums, the public doesn't know much about jellyfish. In addition, their nearly transparent bodies are also easily hidden in the sea.
But there is such a jellyfish that you want to ignore. It's the big Mac of jellyfish, nomura Jellyfish.
Image credit: The Asahi Shimbun
Adult Echizen jellyfish can reach a diameter of up to 2 meters and a weight of up to 200 kilograms. Although another giant jellyfish mane jellyfish is longer than Echizen jellyfish (mainly tentacle length), the Echizen jellyfish is the largest jellyfish in terms of tonnage and size.
However, don't think that such a large jellyfish is very rare. When they are rampant, it is the most desperate.
In our imagination, hordes of jellyfish are a feast for the eyes. But this massive wave of jellyfish has left fishermen bald.
On November 2, 2009, a 10-ton Japanese fishing boat capsized in the eastern waters of Japan. The seafood that fishermen have worked so hard to catch all day is directly lost. Fortunately, all three fishermen were rescued.
But how can a good fishing boat overturn? It turned out that it was the fishing net that caught dozens of Echizen jellyfish that should not be netted. Fishermen don't want to catch jellyfish, a "garbage seafood" that can't be sold for a few dollars, and they send it to their doors themselves.
In addition to being able to tow down fishing boats, their poisonous tentacles poison the fish in the net.
Even if it is resistant to jellyfish toxins, the catch will still be crushed to death and stinky, and it is difficult to sell for a good price. Excessively heavy jellyfish can also cause damage to expensive fishing nets.
However, the fishing industry is affected by jellyfish tides, and it is no longer a matter of a day or two. In some extreme cases, thousands of Echizen jellyfish can be found in fishing nets.
But every time they saw the Echizen jellyfish, the fishermen could only shake their heads helplessly, thinking that they were unlucky. Because these jellyfish can't be driven away, they can't be killed, and they can't be sold.
The life cycle of Echizen jellyfish, picture translation: Senno youko
The life cycle of jellyfish mainly consists of two alternating life generations, one is the planktonic jellyfish generation and the other is the benthic attached hydra generation.
In general, the reproductive glands of individual mature jellyfish can produce large numbers of sperm and eggs. These germ cells are released into the surrounding water. In water, sperm and eggs combine to produce several floating wave larvae through sexual reproduction. These floating wave larvae can swim around in the water, and once they find a suitable landing site, they will attach to it and transform into a hydra form.
After that, the hydra body can also produce more hydra bodies through asexual reproduction, forming a colony of hydra bodies, waiting to grow into small jellyfish. A female Echizen jellyfish will have nearly 1 billion eggs fertilized successfully. And these successfully fertilized eggs can eventually produce more than 10 billion Echizen jellyfish.
Echizen jellyfish larvae feeding, source CCTV documentary
At present, research shows that the main base of these Echizen jellyfish who are causing trouble in Japan is actually the Yellow Sea, East China Sea and Bohai Sea in China.
Jellyfish are invertebrates whose body consists of an umbrella-like body, mouthparts, and tentacles. Therefore, they also do not have the ability to swim quickly, and can only move slowly by the contraction and expansion of muscles. They were not supposed to be abundant off the coast of Japan, but by transporting them to the Mahai waterway, these Echizen jellyfish would erupt in the Sea of Japan.
The rafting route of Echizen jellyfish
In fact, in Japanese history, only one large-scale Echizen jellyfish outbreak was reported every 40 years or so. But in recent years, this phenomenon has become more and more frequent.
Since 2002, there has been an explosion of Echizen jellyfish almost every year in Japan's coastal areas. This has caused a large-scale damage to Japan's fishery, and the fishermen are suffering for a long time. Between August and October 2005 alone, the Japan Fisheries Agency received a total of 100,000 complaints from all over Japan, but so far, there has been no way to completely resolve the Echizen jellyfish crowd disturbance.
In the past, Japanese fishermen armed with no scientific knowledge made a big mistake. That is, to cut the echizen jellyfish that was fished ashore into ten thousand pieces, and then throw the body into the sea again. Unexpectedly, this operation instead stimulated the rapid maturation of the gonads of the Echizen jellyfish and released a large number of germ cells. And this also recharges the power for the next jellyfish explosion, and the power is even more amazing.
In addition to the damage to the fishing industry, the jellyfish army also captured the cooling facilities of Japan's nuclear power plants.
Many nuclear power plants will be built on the seashore because the generator sets need a lot of seawater to cool to prevent the motor from overheating and damage. But wherever there is seawater, there is a chance of being invaded by jellyfish.
In 2006, large numbers of Echizen jellyfish poured into Japan's nuclear power plant, blocking the seawater filter holes in its cooling system. Workers must get the slimy jellyfish away, or the nuclear power plant will be paralyzed and even pose a safety threat. So some people say that jellyfish invasion has become the second biggest threat to Japan's nuclear power plants, and the first big threat is earthquakes.
The cooling system of an Israeli nuclear power plant blocked by jellyfish
This also adds a lot of complicated daily work to the workers of nuclear power plants. During jellyfish outbreaks, the Japanese were able to remove up to 150 tons of jellyfish from the cooling system of nuclear power plants in a day. This has also caused the gross electricity production of nuclear power plants to decline a lot.
In fact, around the world, nuclear power plants in places such as the United Kingdom, Sweden, Israel and other places have been blocked by various jellyfish. In order to clean up the invading jellyfish, some nuclear power plants even had to shut down the reactors and fell into paralysis.
Jellyfish cleaned from nuclear power plants
In addition, the toxic properties of jellyfish are also worrying. The Latin name of jellyfish is Medusa, the snake-haired banshee in Greek mythology. The reason is that jellyfish have a soft body like Medusa, but poisonous tentacles can kill people.
The tentacles of the jellyfish are distributed with countless spiny cells, and inside the spine cells are the spines containing the stingers. When stimulated, these stingers shoot out a dose of venom. After being stung, in addition to the unbearable pain, humans may even lose their lives.
The "ejection" of the spiny sac in the spiny cell, image source Wikipedia
For example, there are news reports that between December last year and January 7 this year, more than 20,000 people across Queensland, Australia, were hospitalized for treatment for stings by jellyfish in blue bottle caps. The number of stings is also several times that of the same period in Queensland in the past.
Monk's hat jellyfish strewn all over the beach
In addition, the box jellyfish, which is also produced in Australia, is called one of the most poisonous organisms in the world.
Its venom mixes almost all types of toxins and can kill people in a matter of minutes. To date, more than 60 people in Australia have been stung to death by this jellyfish.
Small and poisonous box jellyfish
The jellyfish disaster in recent years has also forced human beings to re-examine jellyfish as a creature.
According to the growth cycle of jellyfish, it is normal for a large number of jellyfish to appear at the same time, and only large-scale outbreaks of jellyfish tides will scientists consider abnormal situations. Although so far, scientists have not really determined that there are large-scale outbreaks of jellyfish worldwide. Because studying groups of jellyfish whose whereabouts are hidden is not an easy task.
There is also a theory that the explosion of jellyfish in recent years coincides with the natural fluctuations of the environment. That is, although the overall jellyfish population is on the rise, this increase may still be within the normal fluctuation range.
Population trend charts for jellyfish are generally rising, with red (high certainty) and yellow (low certainty) parts increasing, green being stable, and blue being decreasing
However, from the nature of the jellyfish itself, this problem may not be very optimistic. Especially in the context of global warming and overfishing, jellyfish with strong adaptability can take advantage of the void to multiply and quickly occupy the ecological niche.
In almost every corner of the ocean, there are jellyfish figures. In terms of time span, they are the oldest creatures on Earth, dating back to 560 million years. The various Earth overlords who appeared later than them are extinct, but the jellyfish that have endured countless earth turmoil have stubbornly survived. It can be said that what a harsh earth environment, jellyfish have seen.
Don't look at them floating in the water all day long, but this mode of survival is also the result of a long evolution, full of wisdom.
The jellyfish with a transparent body is like an invisible killer. Although they do not actively hunt, jellyfish with a wide range of diets are the most savvy opportunists. They eat everything that comes to their mouths, such as plankton, fish eggs, small fish and crustaceans, and almost none of them are spared.
For example, Echizen jellyfish grow to hundreds of pounds at every turn. If they want to maintain such a large size, they need to eat thousands of cubic meters of phytoplankton in the sea every day.
In addition to being excellent predators, jellyfish are competitors for other marine life.
For those fish that feed on plankton, the food they rely on will be eaten by jellyfish, and the survival resources will be squeezed. At the same time, their eggs and fry will also be eaten by jellyfish, which is a double blow.
Of course, jellyfish also have natural enemies. Although most fish are dismissive of jellyfish, which have little to no nutrition. But creatures like sunfish, turtles, penguins and others still prey on jellyfish. It is only in the case of global fishing that the population size of these only natural enemies of jellyfish is also declining, and its status is precarious. Without the limits of predators, the number of jellyfish will explode unchecked.
Turtle "Powder"
In addition, jellyfish also have a stronger ability to adapt to environmental changes than other marine organisms. They are well adapted to acidified, hypoxic, warming and eutrophicationic seawater environments.
But these poor environments are not conducive to the survival of other fish, and this allows jellyfish to profit from them again. In other words, the worse the environment, the better the jellyfish can live. This is positive feedback for jellyfish, but a vicious circle for other fish. Some scholars describe this as like a drug-resistant bacteria meeting a patient with a weakened immune system.
Coupled with the ability of jellyfish to reproduce against the sky, this almost makes jellyfish fall into a dilemma once a large-scale outbreak occurs. So some people say that jellyfish are cockroaches in the ocean. If most of the animals in the ocean disappear, jellyfish will be the hegemon.
When a species is flooded, the first thing many people think of is "eating". But developing jellyfish recipes is not an easy task.
Jellyfish are gelatinous plankton, more than 95% of their bodies are water, a pound of jellyfish is only a few dozen calories, and the calorie is lower than that of cucumbers. Globally, only some countries in East Asia feed on jellyfish. China is the largest jellyfish eating country, cold sauce jellyfish, vinegar slipper jellyfish are classic cuisine. However, the public in Western countries have a hard time accepting the slippery taste of jellyfish.
Low-calorie jellyfish crisp
In order to make the most of their things, many researchers have also invented various ways to eat jellyfish biscuits, jellyfish ice cream, jellyfish crisps and so on. Although it is difficult to solve the problem of jellyfish disaster from the root by eating, this idea is correct for the people, ask the low-calorie, delicious and environmentally friendly way of eating who does not love it!
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