Various species of jellyfish (19) ubozoa), which was previously considered to be an order of the class Phaeophaga. The term jellyfish also refers to jellyfish-shaped (bell-shaped or dish-shaped) stinging animals in a broad sense, such as hydra jellyfish, tube jellyfish (including capuchin jellyfish) and comb jellyfish and sea urchins that do not belong to the class Phaeophaga. Jellyfish in this class can be divided into two types: free-swimming jellyfish and sedentary species (with stalks attached to seaweed and other objects). Hydra-like species that live in a fixed life constitute the order Stauromedusae. Jellyfish appeared before dinosaurs, dating back to 650 million years ago. There are many kinds of jellyfish, about 250 species in the world, ranging in diameter from 10 cm to 100 cm, which are common in the oceans all over the world. The main component of jellyfish body is water, and its water content can reach more than 97%, and it is composed of inner and outer germ layers. There is a thick mesothelium between the two layers, which is not only transparent, but also floating. When they are moving, they use the water spray reflection in their bodies to move forward, just like a round umbrella floating rapidly in the water. There is a special gland in the umbrella of jellyfish, which can emit carbon monoxide and make the umbrella expand. When the jellyfish encounters an enemy or encounters a big storm, it will automatically release its gas and sink to the bottom of the sea. After the sea is calm, it only takes a few minutes to produce gas to make itself expand and float. There is a small ball on the thin handle in the middle of the jellyfish tentacles, and there is a small auditory stone in it, which is the "ear" of the jellyfish. Infrasound waves generated by the friction between waves and air hit the auditory stone, stimulating the surrounding nerve receptors, so that jellyfish could get information more than ten hours before storm warning, and disappeared from the sea at once. Scientists have tried to simulate the sound wave transmitting organs of jellyfish, and found that they can detect the information of ocean storms before 15 hours. Jellyfish is a kind of lower coelenterate, which is common in the oceans all over the world, and is classified according to the different umbrella bodies: some umbrella bodies emit silver light and are called silver jellyfish; Some umbrellas are like a monk's hat, which is called a monk's hat jellyfish; Some umbrellas are like white sails on a ship, called sail jellyfish; Some are like umbrellas, called umbrella jellyfish; Some umbrellas shine with the glow of rosy clouds, called chardonnay jellyfish; Because jellyfish have no respiratory organs and circulatory system, only primitive digestive organs, so the captured food is digested and absorbed in the intestines immediately. Most of them live only a few weeks or months, and some live to a year or so. Some deep-sea jellyfish can live longer. There are about 8 common species in China, namely, sea moon jellyfish, white chardonnay jellyfish, jellyfish, jellyfish and so on. More than 95% of jellyfish's body is water, and the rest is jellyfish made of protein and lipids.
Yes, so the jellyfish's body will be transparent because of the water in the body. Jellyfish has three germ layers, the outermost layer is the epidermis, and the innermost layer is the gastric cortex. The gastric cortex constitutes a simple body cavity with only one opening, which has both oral and excretory functions. Between the epidermis and the gastric cortex is the mesoglea. Take the jellyfish as an example. The jellyfish body has several structures:
Stomach cavity
That is, the gastric cavity formed by the gastric cortex is also the digestive system of jellyfish. There is a Gastrovascular cavity in the gastric cavity, and there are many tentacle filaments in it, and there are Nematocyst on the Gastric filament, which can anesthetize the bait and then release digestive juice for digestion. The gonads are also located on the wall of the gastric cavity and originate from the gastric cortex.
Feeling stick
There are eight haptics on the edge of jellyfish wings, including a balance cell, an Ocellus and two Sensory clubs, which are used to balance their body and sense of touch in water, and can be said to be the sensory organs of jellyfish. Among them, the box jellyfish has 24 eyes and 360 visual senses.
Umbrella cap
There are six sensory organs at the edge of the umbrella, and once something approaches, they will escape quickly according to infrasound waves in seawater.
tentacle
There are many tiny tentacles on the edge of the jellyfish wing, which touch the capuchin jellyfish.
There are stinging cells at the front end of the hand, which can catch plankton and attack the enemy.
Spinocele
As one of the cells at the front end of the tentacle, coelenterates are also called echinoderms, which means that jellyfish are more or less toxic. The stinging cell is a liquid-filled sac with a hollow winding tube. A small needle on the surface of the stinging cell is called a Cindocil, which is like a switch. When the stinging needle is touched, the stinging cell will immediately shoot out of the pipeline. These tubes containing venom will paralyze the stung creature. The toxin emitted by box jellyfish is the most poisonous toxin in the world. So far, there is still no serum to save it. But if you wash the wound with vinegar within a certain period of time, you can save your life, and then send it to the hospital immediately for further treatment.
oral arm
The number of wrists extending from the center of jellyfish wings is the same as that of stomach sacs. There are also many stinging cells on the mouth and wrist, which can not only catch prey, but also send food into the mouth. There is an incubator at the bottom of the mouth and wrist, and the solid sac larvae developed from fertilized eggs will attach to the incubator.
mouthparts (of an arthropod)
Located at the base of the mouth and wrist, it directly leads to the stomach cavity. Can be eaten in addition to food, but also has the function of excretion.
Radiation tube
The tube extending radially from the stomach cavity to the jellyfish wing can circulate digested nutrients and oxygen in the body, which has a vascular function.
Edit the life habits of this paragraph
Although jellyfish are beautiful and docile, they are actually very fierce. Under the umbrella, those slender tentacles are its digestive organs and weapons. The tentacles are covered with stinging cells, which, like poisonous silk, can shoot venom. After being stung, the prey will quickly become paralyzed and die. Tentacles will hold these prey tightly, retract them, and suck them with polyps under the umbrella. Each polyp can secrete enzymes, and quickly decompose protein in the prey. Because jellyfish have no respiratory organs and circulatory system, only primitive digestive organs, so the food they catch is immediately a capuchin jellyfish.
Digestion and absorption in the intestine. In the hot summer, when we swim in the tide at the seaside, sometimes we suddenly feel a stabbing pain in our chest, back or limbs, as if we were whipped by a whip. It must be that jellyfish are stabbing people again. However, if you are stung by jellyfish, you will only feel burning pain and redness. As long as you apply anti-inflammatory drugs or edible vinegar, you can reduce swelling and relieve pain in a few days. However, in the sea from Malaysia to Australia, there are two species called sea bee jellyfish (box jellyfish) and hand-dragging jellyfish, which secrete very toxic substances. If stung by them, they will die of dyspnea within a few minutes, so they are also called killer jellyfish. Therefore, when you are stabbed by jellyfish and have difficulty breathing, you should immediately carry out artificial respiration or inject cardiotonic, and you must not be careless to avoid accidents. Once a jellyfish meets its prey, it never lets it go easily. But just like a rhinoceros and a bird that cleans its parasites, jellyfish have their own partners. It is a small herding fish, only 7 cm long, and it can swim freely between the tentacles of jellyfish, but it is not afraid at all. When a big fish comes, the small shepherd fish swims to the middle of the tentacles under the giant umbrella as a safe "refuge", using the device of jellyfish stinging cells to cleverly escape the attack of the enemy. Sometimes, the small herding fish can even lure the big fish into the hunting range of jellyfish to kill them, so that they can eat the scraps left by jellyfish. So why don't the stinging cells on the tentacles of jellyfish hurt the small shepherd fish? This is because the small shepherd fish is flexible, can skillfully avoid the poisonous silk, and is not easy to be hurt, but it is only accidental and accidental to die under the poisonous silk. Jellyfish and small herding fish were born together and used for each other. Jellyfish "protected" the small herding fish, and the small herding fish swallowed the small creatures inhabiting the jellyfish. There is a small ball on the thin handle in the middle of the jellyfish tentacles, and there is a small auditory stone in it, which is the "ear" of the jellyfish. Infrasound waves generated by the friction between waves and air hit the auditory stone, stimulating the surrounding nerve receptors, so that jellyfish could get information more than ten hours before storm warning, so they seemed to have received orders and disappeared from the sea at once. Scientists have tried to simulate the sound wave transmitting organs of jellyfish, and found that they can detect the information of ocean storms before 15 hours. Jellyfish is an inferior coelenterate, but it runs in the family is enviable. Jellyfish give birth to small jellyfish. Although small jellyfish can survive independently, it seems that there is a deep affection between parents and children, so small jellyfish are attached to the jellyfish body. Soon after, the little jellyfish gave birth to grandchildren's jellyfish, which are still closely linked.
method of excercise
Jellyfish changes the volume of the inner cavity by shrinking the shell and squeezing the inner cavity, ejects the water in the cavity, and moves by spraying water. Muscle fibers extending from the top of jellyfish epidermis to the end of umbrella body control the contraction and expansion of inner cavity. The lumen expands, and the water slowly sucks in, filling the lumen; The inner cavity shrinks rapidly, squeezing the water out of the cavity, and the thrust generated by the water jet makes the jellyfish move along the axial direction of the body. When the jellyfish tries to sink in the water, its tentacles extend and upward in a long line; When trying to rise or move in a certain direction, the distal end of the tentacle bends against the direction of movement. With the help of tentacles, jellyfish can effectively change the direction of movement. Some jellyfish have a special gland in the bell-shaped body, which can emit carbon monoxide and make the bell-shaped body swell. And when jellyfish meet multiple jellyfish,
When the enemy harms or encounters a big storm, it will automatically release the gas and sink to the bottom of the sea. After the sea is calm, it only takes a few minutes to generate gas to make itself expand and float. In addition, some jellyfish have airbags at the top of their umbrellas. These jellyfish can control the amount of inflation in each airbag and also change the direction of movement of jellyfish. Jellyfish are not good at swimming. They often move with the help of wind, waves and current. Morphological characteristics depend on the simple way of movement, and jellyfish has a simple shape. Jellyfish looks like a transparent umbrella, and the diameter of the umbrella is large and small. The umbrella of ordinary jellyfish is not very big, only 20 ~ 30 cm long, while the umbrella of big jellyfish can reach 2 meters in diameter. Some whisker-like strips grow from the edge of the umbrella, which are called tentacles. Some tentacles can be as long as 20 meters to 30 meters, which is equivalent to the length of a big whale. Jellyfish floating in the water extend long tentacles around, and some jellyfish have umbrellas with various patterns. In the blue ocean, these swimming elves with different colors look very beautiful 1865, on the coast of Massachusetts, USA, a jellyfish was washed ashore by the waves. Its umbrella was 2.28 meters in diameter and its tentacles were 36 meters long. Pull the tentacles of this jellyfish apart, and it is 74 meters long from the tip of one tentacle to the tip of the other. Therefore, it can be said that the jellyfish is the longest animal in the world. Jellyfish can be divided into three main parts: one is a circular umbrella body, which swims by shrinking and releasing; The second is the tentacle, which is used to control the direction of movement in swimming, and is covered with stinging cells to catch and paralyze prey; Third, other parts, including genitalia, limbal membrane, digestive system, balance sac and so on.
Predation mode
Jellyfish are beautiful but fierce. Under the umbrella, those slender tentacles are its digestive organs and weapons. The tentacles are covered with stinging cells, which, like poisonous silk, can shoot venom. After being stung, the prey will quickly become paralyzed and die. Tentacles will hold these prey tightly, retract them, and suck them with polyps under the umbrella. Each polyp can secrete enzymes, and quickly decompose protein in the prey. Because jellyfish have no respiratory organs and circulatory system, only primitive digestive organs, so the captured food is immediately digested and absorbed in the lumen. Once a jellyfish meets its prey, it never lets it go easily. In the hot summer, when we swim in the tide at the seaside, sometimes we suddenly feel a stabbing pain in our chest, back or limbs, as if we were whipped by a whip. It must be that jellyfish are stabbing people again. However, if you are stung by jellyfish, you will only feel burning pain and redness. As long as you apply anti-inflammatory drugs or edible vinegar, you can reduce swelling and relieve pain in a few days. However, in the sea from Malaysia to Australia, there are two kinds of jellyfish called draghand jellyfish and box jellyfish (or sea wasps), which secrete very toxic substances. If stung by them, they will die of breathing difficulties within a few minutes, so they are also called killer jellyfish. Therefore, when you are stabbed by jellyfish and have difficulty breathing, you should immediately carry out artificial respiration or inject cardiotonic, and you must not be careless to avoid accidents. [ 1]
Breeding mode
Breeding jellyfish are hermaphroditic, with gonads near the gastric sac. Mature sperm flows into female jellyfish for fertilization. The fertilized egg develops into a larva, leaves the mother, swims in the water for a while, sinks to the bottom of the sea to form a larva, and then becomes a hydra, which splits into a plurality of disc-shaped larvae and then develops into a jellyfish adult. Surplus In recent years, sudden jellyfish swarms often appear in the seas around the world. Earlier, a giant group of "Yueqian jellyfish" appeared in Japanese waters. It is estimated that the Yangtze River basin in China is one of the sources of Yueqian jellyfish. With the overfishing of coastal industries in China, the number of fish competing for food with jellyfish has decreased, and plankton has increased, resulting in excessive jellyfish reproduction. In addition, a series of abnormal heavy rains in the Yangtze River basin have washed giant jellyfish into Japanese waters. In addition, the warming of the ocean water temperature also accelerates the reproduction and growth of jellyfish. According to the latest report of National Geographic magazine, jellyfish mostly live in stagnant water areas, and their life is extremely tenacious. It hardly needs oxygen, so you will find it in the deep sea area of several thousand meters. The appearance of jellyfish is not a phenomenon of environmental improvement, but a symptom of environmental deterioration. With the serious water pollution, abundant nutrients and disastrous plankton, resulting in a large number of fish deaths, jellyfish began to flourish, but this is a prelude to another disaster, jellyfish eat everything, plankton, fish eggs, small fish, big fish ~ all escape, its prosperity makes it difficult for fish to regenerate, and the consequences will be irreversible! Japan has tasted the disastrous consequences of jellyfish's prosperity, so please pay close attention to environmental pollution and its disastrous consequences! There are still ways to change this situation. First, pay attention to the problem of water pollution and actively solve the problem of water pollution in industrial production. Second, sea turtles are natural enemies of jellyfish, so we should strengthen the protection of sea turtles.
Luminous cause
Jellyfish is a kind of cellular animal, with simple structure, no muscles and bones, and 98% of its body is water. How is its light?
What about it? The ctenophore swims in the sea, and its body shows spherical blue light. The long tentacles behind it are shining with slender light bands. As the ctenophore swims, its body bends and swings, the light is also varied and beautiful. It turns out that the light source of jellyfish is different from that of other animals. Most other animals emit light through the catalysis of oxygen by fluorescein and luciferase. However, jellyfish glow by a magical protein called Aquiline. This protein can emit strong blue light when it meets calcium ions. According to scientists' research, each jellyfish contains about 50 micrograms of aequorin, which shows that jellyfish rely on it to shine.
Natural enemies of jellyfish
Powerful and deadly jellyfish also have natural enemies, so leatherback turtles can freely shuttle among jellyfish, easily break their tentacles with their mouths, so that they can only roll up and down, and finally lose their resistance, becoming a "delicious meal" for turtles.