Characteristics and living habits of egg yolk jellyfish

Egg yolk jellyfish (scientific name: cotylorhiza tuberculata) is a marine organism of the order root mouth jellyfish of the class bowl jellyfish. There is also a name “Medusa” with the same name as the Banshee in Greek mythology. The jellyfish is large, and the umbrella body is generally 35 cm in diameter, up to 50 cm at most. The umbrella is disc-shaped. Due to the color of the reproductive gland or other gastric sac in the body, the golden red or orange red bulge in the center appears in the transparent body. It looks so delicious and attractive, just like a poached egg.


The main stages of life history are monomer and jellyfish, and the Hydra stage is underdeveloped. The body is large and has no marginal membrane; The gastric circulation cavity is complex, the radiation tube is developed, there are gastric filaments of endoderm origin, and there are barbed cells on the gastric filaments; Germ cells originate from the endoderm, and the nerve senses are developed, forming 8 sensory organs.
Learning to live in the sea, jellyfish are armed with harpoon tentacles. When they touch their prey, they will shoot the venom of thorn cells on their tentacles and hunt their prey. Similar in shape to boiled eggs, it is the most common jellyfish in the Mediterranean and also distributed in the Aegean and Adriatic seas.
brief introduction
The live “egg yolk” living in the ocean is actually a kind of jellyfish. It is called egg yolk jellyfish. Just like its name, it has a shape similar to egg yolk, which makes people think at first glance that it is an egg yolk floating on the water.
The umbrella of egg yolk jellyfish is generally 35 cm in diameter and up to 50 cm in maximum. It belongs to a relatively large body size. The jellyfish umbrella is disc-shaped due to the structure of gonads or other gastric sacs in the body. The egg yolk jellyfish has color, and the golden red or orange red bulge in the center of the body appears in the transparency. It looks so delicious and attractive, just like a poached egg just boiled.
Jellyfish in marine life use harpoon tentacles as weapons. When they touch their prey, they will shoot the venom of stinging cells on their tentacles and hunt their prey. It is sent to the inlet and gastric cavity through the mouth wrist groove by the action of cilia. The barbed cells on the gastric filament kill the catch, and then the gland cells on the gastric filament secrete digestive enzymes to digest the food. The digested nutrients swing by the cilia on the wall of the circulating tube to promote the nutrients from the gastric cavity into the ring tube from the radial tube, and then the undigested and absorbed food residues are discharged from the body through the positive radial tube, intermediate radial tube, gastric cavity and mouth.
morphological character
The egg yolk jellyfish is large, and the umbrella diameter is generally 35 cm, up to 50 cm at most. The umbrella is disc-shaped. Due to the color of the reproductive gland or other gastric sac and other structures in the body, the golden red or orange bulge in the center appears in the transparent body. It looks so delicious and attractive, just like the poached egg just boiled. The edge thickness of the umbrella body is usually about 17 cm. The body is divided into upper umbrella surface and lower umbrella surface, without marginal membrane. The umbrella edge has no tentacles, the wristband heals, and the mouth at the end of the vertical lip is closed to form many new small suction ports. In the early development, it has a normal mouth and has 8 mouth leaves. In the later development, it forms 8 wristbands, and the wristbands branch and heal again. The ciliary groove in the original wristband heals into tubules and suctorial mouth. The suction port and small tube are connected with the gastric cavity. Spiny cells are generally distributed on the outer surface of vertical lips, wrists and umbrellas. The middle layer is very developed. It is also a gel formed by protein and mucopolysaccharide, which contains collagen fibers. The middle glue layer also has great elasticity. Because it can maintain and adjust the composition and concentration of ions, the body can maintain a certain buoyancy in seawater. Muscle and movement are similar to Hydra jellyfish. There are circular muscles formed by ectoderm around the lower umbrella edge. Their contraction causes the movement of jellyfish.
Living habits
The gastric circulation cavity of egg yolk jellyfish is more complex than that of Hydra jellyfish. The original species enter the central gastric cavity from the mouth through the vertical lip. The gastric cavity extends outward to form four gastric sacs. There is a septum between the gastric sacs, and there are small holes on the septum, which can make the gastric sacs communicate with each other to help the circulation of liquid. There are diaphragm muscles on the diaphragm and gastric filaments of endoderm origin on the inner edge. It contains many thorn cells and gland cells, which can fix and kill food entering the gastric cavity. This structure of gastric sac and diaphragm only appears in infancy, and a developed gastric cavity and circulating duct system are formed in adulthood. It is a carnivorous animal that feeds on small crustaceans and plankton. In fact, it is also a kind of suspended predator. The tiny plankton in the water is filtered by tentacles and sent to the inlet and gastric cavity through the mouth wrist groove by cilia. The thorn cells on the gastric filament kill the catch, and then the gland cells on the gastric filament secrete digestive enzymes to digest the food, The digested nutrients swing by the cilia on the wall of the circulating pipe to promote the nutrients to enter the ring pipe from the gastric cavity through the radial pipe, and then discharge the undigested and absorbed food residues out of the body through the positive radial pipe, intermediate radial pipe, gastric cavity and mouth.
In late summer and early autumn, large groups gathered together, which really caused harm near the beach, causing great trouble for human fisheries and ship travel.
Distribution range
It is distributed in the Mediterranean Sea, Aegean Sea and Adriatic Sea. The Mediterranean is the most abundant.
Breeding mode
The egg yolk jellyfish is male and female, and the gonads are located in the stomach and produced by the endoderm. The original species had 8 gonads on both sides of the diaphragm. Sexual maturity often has color and is easy to identify. The germ cells are discharged into the sea water or at the wrist of the mouth for fertilization. The fertilized egg develops into floating wave larvae at the blastocyst stage. After a period of free swimming, it is fixed on the object with its front end and develops into Hydra type larvae, which is called Scyphistoma. After that, the Scyphistoma carries out Strobilation from the top to the base, which is called strobila, Later, the transverse fission body separates from the mother from the top to form a young jellyfish type body, called ephyra. The transverse fission body can live for one to several years. After all the transverse fission bodies fall off, it can re form bowl mouth larvae. Therefore, the transverse fission body is an asexual reproductive stage. The butterfly larva is very small with deep notches on the edge. It developed into a jellyfish type adult after a large amount of feeding.

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