Like a colorful custard, it dances a "two-step dance" in the quiet water, elegant and light. However, swimmers talk about tiger discoloration, fishermen are far away, even biologists do not know much about them. They are just seemingly weak and beautiful - jellyfish,
A low coelenterate that taxonomically belongs to the order Phytophthalmos. Jellyfish and polyps are close relatives, and their body structure is very simple: the main component is water, there are two layers inside and outside, and there is a thick medium rubber layer between the two layers, which is not only transparent, but also has a floating effect. When the jellyfish is moving, it uses the reaction force of the water spray in the body to move forward, and it looks far away, like a round umbrella floating rapidly in the water. Jellyfish have no specialized digestive organs, only digestive chambers, in which spoke-like catheters are the organs that transport nutrients; tentacles have thorn cells, which are filled with venom. Some species of jellyfish have a total tentacle length that exceeds the body length of a blue whale.
The umbrella-like body of an adult jellyfish is called a "jellyfish body". People usually classify jellyfish according to the shape of the jellyfish: some can emit silver light, called silver jellyfish; some are like monks' hats, called monk hat jellyfish;
Portuguese man-of-war
Some are like sails, called sail jellyfish;
Sail jellyfish
Some are like umbrellas, called umbrella jellyfish;
Umbrella jellyfish
Some jellyfish have a glow like a rainbow on their bodies, called Kasumi jellyfish...
Kasumi jellyfish
Most jellyfish have a lifespan of only a few weeks, and some deep sea mothers have a longer lifespan and can live to about a year. The jellyfish of ordinary jellyfish is not large, only 20 to 30 cm long, while the diameter of the larger Jellyfish jellyfish can reach 2 meters, and its sagging tentacles are up to 20 to 30 meters long. In 1865, off the coast of Massachusetts, the United States, a Xiaxia jellyfish was washed ashore by waves, and its jellyfish was measured to be 2.28 meters in diameter and 36 meters in tentacle length. Spreading the tentacles, from the tip of one tentacle to the tip of another, it is 74 meters long. It can be said that kasumi jellyfish is the longest animal in the world.
Large Kasumi jellyfish
Jellyfish have no eyes, no ears, and even no brains, and live a "headless, brainless" life in the vast ocean. Nevertheless, they remain a not-to-be-underestimated member of the family of marine life. There are many types of jellyfish, about 250 in the world. Next, let's look at some peculiar jellyfish.
"Sea Swordsman" - box jellyfish
Two years ago, a seven-year-old boy was swimming on Mysin Beach in Queensland, Australia, when he suddenly let out a frightening scream, and by the time his grandfather dragged him out of the water, the boy who was writhing in pain had collapsed and soon fell into a coma, and within an hour his heart had stopped beating. This is the most recent case of the death of a box jellyfish stinging man.
In Australia, box jellyfish are known as the "Swordsmen of the Sea". Australian ecologist Jamie Seamore is fascinated by box jellyfish, and for him it is not only a research topic, but also a matter of life and death. To prevent box jellyfish from hurting more people, Schimoll tried to use radio tracking technology to study box jellyfish. But how do you attach a "label" — a tiny ultrasonic transmitter 4 centimeters long and 12 millimeters in diameter — to a slippery, erratic ball? At first, Shymore used non-toxic superglue to attach "labels" to jellyfish umbrellas, making him the first scientist in the world to "label" jellyfish. However, this method is not perfect, and Schimoll has only succeeded seven times since it began tracking box jellyfish in 2015. And, frustratingly, each "label" falls off in less than two days. Currently, Schimoll is working on a way to attach "labels" to jellyfish so that "labels" may not easily fall off.
From 28 different types of box jellyfish, Schmol selected the largest bell jellyfish he tracked, which can grow as large as a basketball, with up to 60 tentacles, the longest tentacle reaching 4.5 meters, and about 5 billion spine cells.
The box jellyfish did not kill people intentionally, but if a person is accidentally swept by it, it may be killed within minutes by being injected with venom, and even if it is lucky enough to survive, it will leave a permanent purple scar on the body. Seamore had such a terrible experience. One night, while cruising the waters near a pier, he came across a large box-shaped jellyfish. He later recalled: "Before I could react, my hands and feet were already wrapped around the tentacles. By the time I struggled to break free and float to the surface, I couldn't walk well and burst into tears. "Seamore was able to save his life thanks to the fact that he was wearing an elastic wetsuit at the time, and immediately after landing ashore, he took effective self-help measures - soaking his body in vinegar. Vinegar breaks down the venom released by box jellyfish, and in Australia, experienced lifeguards have vinegar on hand.
The best way to avoid contact with box jellyfish is to understand their movements, when and why. Most jellyfish are drifting animals without eyes, but box jellyfish are different, with a total of 24 eyes in compound eyes and one eye, with excellent vision required to hunt fish. In addition, the box jellyfish swim very fast, can swim 1.5 meters in one second. Some box jellyfish also have a very unique habit: they are active during the day and stand still on the seabed at night. This is a behavior not seen in other jellyfish.
Schimoll's colleague Teresa Carett found that box jellyfish become more lethal with age: young jellyfish have only about 5 percent of the spiny cell virulence, while adult jellyfish have 50 percent spiny cell venom, allowing them to prey on larger prey.
Today, Australians are much more alert to box jellyfish, protective nets are mostly used on beaches, and the number of cases of box jellyfish stinging is decreasing.
"Beauty Killer" - Spotted Jellyfish
In the tranquil lagoon near the Palau archipelago in the Indian Ocean, there are some beautiful lagoon jellyfish, one of which is the spotted jellyfish. Although spotted jellyfish belong to the same coelenterates as their ancestors (which also include polyps in this population), there are many differences. Spotted jellyfish float in the lagoon and feed on marine plankton. Spotted jellyfish look beautiful and docile, but in fact, some of them are very fierce and are the "beauty killers" in the ocean. Beneath their umbrella-like bodies, the slender, long tentacles are both digestive organs and "lethal weapons"—they are covered with stinging cells that can quickly shoot out venom, and once the prey is stung, it will soon be paralyzed and die. At this time, the spotted jellyfish then grasps the prey tightly with its tentacles, retracts it, and sucks the prey with the polyp under the water mother's body. The polyps of spotted jellyfish secrete enzymes that can quickly break down proteins in prey. Jellyfish have no respiratory organs and circulatory system, only primitive digestive organs, so the captured food must be digested and absorbed in the coelum.
Spotted jellyfish undergo complex life cycles throughout their lives. When the jellyfish matures, it begins to lay eggs and release semen, and soon the fertilized eggs hatch into larvae, and after a few days the small jellyfish that drifts with the waves can attach to solid surfaces such as rocks. After that, the young jellyfish begin to develop, and their bodies resemble miniature sea anemones. Soon, anemone-like jellyfish can give birth to more small jellyfish, and they will eventually become adults as long as the environmental conditions are suitable.
The Palau Lagoon was formed between 12,000 and 15,000 years ago,
At the end of the First Ice Age, sea levels rose and sea water poured into land to form lakes. Later, the sea receded and the salinity of the lake gradually decreased, eventually forming the current lagoon. The reefs of the Palau Archipelago are mostly sandstone-like peaks formed of limestone, covered with weathered and eroded ravines. The sea water seeped through the limestone into the island's huge lagoons, "incidentally" bringing with it the newly hatched baby jellyfish and other marine life. In this unique environment, lagoon jellyfish not only survived, but also multiplied for generations, eventually evolving into 5 different subspecies.
Usually the stingers on the tentacles of the spotted jellyfish are their weapon for attacking their prey, but the spotted jellyfish living in the Palau lagoon do not have stingers, perhaps the pleasant environment of the lagoon has turned this "killer" animal into a more gentle and elegant "herbivores" that mainly rely on seaweed creatures for their livelihood. However, lagoon jellyfish do not eat seaweed, but rely on the excrement of seaweed photosynthesis, which provides them with about 3/4 of the energy, and the rest is obtained by preying on other plankton. In this way, the hunting behavior of lagoon jellyfish is more like that of a large farmer who occasionally hunts, and if he has a harvest, he can taste wild game, but he will never go hungry because he can't catch his prey.
The relationship between spotted jellyfish and seaweed is more like a symbiotic relationship: jellyfish feed on excrement after seaweed photosynthesis, while jellyfish absorb sunlight as their greatest benefit to seaweed in order to help seaweed better photosynthesis. Thus, in the Palau Lagoon, chasing the sun becomes a "compulsory course" for jellyfish every morning – when the first rays of the morning sun shine on the east side of the lake, they swim to the east, and when the evening sun shines on the west side of the lake, they swim to the west like a swimming silk, thus forming a unique landscape of the Palau Lagoon.
Jellyfish habitat coral reefs
Coral reefs are a type of limestone (chemically known as calcium carbonate) deposits distributed in shallow seas, formed by a variety of animals and plants in the ocean that secrete calcium carbonate during growth. There are three types of coral reefs in modern oceans: shore reefs, barrier reefs, and atolls.
Shore reef: grows on the coast of the mainland and around the edge of the island, the distribution width from 10 meters to 100 meters, the distribution range and morphology are closely related to the coastal underwater topographic characteristics and water depth. In the early stages of shore reef coral growth, it is generally small in size but has a wider distribution range. There are scattered coral reefs around Hainan Island in China.
Barrier Reef: Surrounded by land like a castle, it is called a barrier reef.
Between the barrier reef and the land, separated by a body of water several kilometers to tens of kilometers wide, this area is called a lagoon because it is basically surrounded by coral reefs (the lagoon originally refers to a shallow bay, which is closed to the lake due to silt accumulation, but can communicate with the ocean at high tide). The water depth of the lagoon is generally tens of meters, and the deepest can reach hundreds of meters. The barrier reef itself ranges from a few hundred meters to thousands of meters. Barrier reefs are largely continuous, with gaps in some places that connect the lagoon to the open sea. The largest barrier reef in the world is often referred to as the Great Barrier Reef off the east coast of Australia, which stretches south from the northeast coast of Australia for 2010 kilometers intermittently.
Atoll: Similar in distribution morphology to barrier reefs, it does not grow around land or in oceans close to land, but forms a group of coral island reefs in the ocean. A fully developed atoll consisting of a surrounding reef ring, a shallow lagoon in the middle and several coral islands in the lagoon. Reefs are distributed in a circular shape, with a diameter of several kilometers to tens of kilometers. At high tide, the reef is submerged underwater, and through the crystal clear water, you can see the contours of coral reefs lurking under the water. Since the reef grows in shallow water, the waves pass here to produce broken waves, which, when viewed from above, form silver-white rings.