Egg yolk jellyfish, also known as Mediterranean jellyfish, is a marine organism of the family Crestaceae. It is larger, with an umbrella diameter of about 35 cm and a maximum of 50 cm. The umbrella body is disc-shaped, and due to the color of structures such as the reproductive glands and other stomach sacs in the body, the body appears in transparency with a central bulge of golden red or orange red, which looks like a poached egg. It is the most common jellyfish in the Mediterranean Sea and is also found in the Aegean and Adriatic Seas. In late summer and early autumn, large groups are gathered.
The body is divided into upper and lower umbrella surfaces, without membranes. The umbel has no tentacles, the mouth and wrist heal, and the mouth at the end of the vertical lip is closed, forming many new tiny tubes and suction holes for suction. Feeds on small crustaceans, plankton, etc. The suction port and tubules are connected to the gastric cavity. There are usually spines distributed on the outer surface of the hanging lip , wrist and umbrella. The medium rubber layer is very developed, which is a gel formed by proteins and mucopolysaccharides, which contains collagen fibers. The medium rubber layer can maintain and regulate the composition and concentration of ions, while maintaining a certain buoyancy in the seawater.
Jellyfish are important planktonic marine organisms in the aquatic environment. It is widely distributed in the world's major oceans, with about 250 species. Their bodies resemble a transparent umbrella, with large and small diameters, and large jellyfish with an umbrella diameter of up to 2 meters. The edges of the umbel have whisker-like tentacles, some of which can be up to 20-30 meters long. The top of the tentacle is covered with stinging cells, which can shoot out venom, and the prey will quickly paralyze and die after being stinged. The main component of the jellyfish's body is water, and it is composed of two germ 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.