The Jellyfish have different morphologies that represent several Cnidarian classes: Scyphoza (over 200 species), Stauroza (50 species), Cuboza (20 species) and Hydroza (1000-1500 species).
Jellyfish are found in all the oceans from the surface to the depths. Some jellyfish can be found in fresh water, they are only 25mm freshwater species, they are colorless and do not sting.
Jellyfish are generally transparent or translucent. Cyanea capillata is the largest known and longest jellyfish in the world.
Its tentacles are 36.5m. The most common giant jellyfish is found in the waters of Japan, Korea and China. Its diameter is about 200cm and the weight is 200kg. Since jellyfish are not really fish, the jellyfish word is considered an improbable term, so American public aquarists have popularized the terms jellyfish and jellyfish.
The jellyfish word is used to designate different types of cnidarians, which have the basic body structure similar to an umbrella. Scientists use different terms for jellyfish (eg zooplankton gelatinous).
Even if there are no fish, jellyfish are carnivorous animals. They catch prey with tentacles. By tentacles it injects a venom that paralyzes or even kills the prey.
The concentration and composition of the venom differs from one species to another. Certain jellyfish species develop a strong venom that can kill an adult man in just a few minutes.
Some jellyfish have the ability to swim something faster by actively pursuing their prey if the venom is weaker or the animal has escaped.
Jellyfish consumes all types of plankton in life, from plants to microscopic animals in water. They eat fish eggs or larvae from other animals, mollusks, crustaceans, or other jellyfish species.
Jellyfish do not have digestive systems, respiratory system, central nervous system or circulatory system. They do not need a respiratory system because their skin is very thin and the body oxygenates through diffusion.
They have limited movement control, but they are moving through pulse contractions of the bell body. Some species swim most of the time while others are more passive, preferring to save energy.
Jellyfish are composed of 90% of water, most of which is gelatinous, hence the name of jelly. The jellyfish has no brain and nervous system, but there is a network of nerves in the epidermis. Some can detect the presence of light with sensitive organs.
The presence of “flowers” in water is usually seasonal and occurs with the appearance of the sun and temperature rise. Ocean currents tend to gather jellyfish into groups of hundreds of thousands of individuals.
Jellyfish are able to survive in poor water in oxygen or salt water containing more iodine.
Increasing global temperature means increasing the temperature of the water, which means that many species of jellyfish live better in warmer waters. Jellyfish are found in groups that can reach 100,000 individuals.
Due to the warming of water, some jellyfish populations have increased their number so much that some species have been classified as invasions. The invaded areas are the Black Sea, the Caspian Sea, the Baltic Sea, the Mediterranean Sea and the Gulf of Mexico.
Jellyfish can cause people trouble. The most common are stinging (sometimes deadly, depending on the species). Another problem is that many people do not know them well, but they know that some people can cause health problems and this affects tourism.
Destroying fishermen’s nets is another problem. Only Scyphozoan jellyfish are harvested to be eaten, about 12 of the 85 recollected species.
Traditional methods of processing involve procedures that last 20 to 40 days after removal of gonads and mucous membranes.
The umbrella and tentacles are treated with a mixture of salt and other ingredients. Due to the large amount of water jellyfish loses 7-10% by weight during processing.
After processing the remaining mass contains 94% water and 6% protein. Fresh jellyfish are creamy, but during prolonged storage, the color becomes yellowish or brown.
In China, jellyfish are processed and left over to the night. The next day they can be boiled. It can be served with oil, soy sauce, vinegar, sugar, as vegetable salad, etc.
In Japan, sliced and served with vinegar as an appetizer.
Jellyfish are usually male or female (occasionally they also meet hermaphrodites). In most cases eggs are released into the water without being protected and fertilized.
In some species, the sperm swim in the female’s mouth to fertilize the eggs inside the body. After fertilization, a larva called planula is formed.
Planula is small and covered with lilies. It rests on a rigid surface and develops into a polyp. Polip has the shape of a cup and begins to defend the tentacles around an orifice.
Then grow the jellyfish as we know it. The life of the jellyfish lasts from a few hours (in the case of very hydromeducts) to years, depending on the species.
A species has a longevity even up to 30 years, an unusual thing for jellyfish. A species, surpassing Turritopsis, can be immortal because of its ability to transform between jellyfish and tulip.
They feed on continually. In most species, reproduction is controlled by light so that the population deposits the eggs in dusk or dawn.