Sea jellyfish | Facts & Information

# Sea jellyfish | Facts & Information

Sea jellyfish | Discover Fascinating Facts and Information About Sea jellyfish

Jellyfish, also known as jellies or sea jellies, are part of Cnidaria. They have different morphologies representing several cnidarian classes: Scyphoza (over 200 species), Staurosis (50 species), Cubosis (20 species) and Hydroza (1000-1500 species).

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Sea Jellyfish

Sea jellyfish

Jellyfish are some of the most fascinating creatures that inhabit the depths of the ocean. These intriguing animals, with their supernatural appearance, are also known as "marine shadows" or "jellyfish whales". Despite their delicate and fragile appearance, jellyfish are adapted to the life and conditions of the deep ocean, making them capable of surviving and thriving in their extremely hostile natural habitat.

There is a huge variety of jellyfish species, the most famous of which is the common jellyfish, also known scientifically as Aurelia aurita. This species is found in numerous oceans around the world and is characterized by its transparent body and umbrella shape. Although the size of the common jellyfish can vary, most individuals have a diameter of 25-40 centimeters.

Jellyfish do not have a long lifespan, typically living only a few years on average. However, during this short period of time, they can go through the reproductive process multiple times. The reproductive process of jellyfish is complex and interesting, consisting of a life cycle with two distinct stages: a medusoid stage, in which the jellyfish are most remarkable and recognizable, and a planula stage, in which the jellyfish appear as drifting larvae.

One fascinating aspect of jellyfish is their ability to glow in the dark. Specifically, they are bioluminescent, meaning they produce and emit their own light. This extraordinary adaptation is useful for jellyfish in an environment where light is scarce or absent. The production of light can be used both as a mechanism for defense against predators and as a means of communication within the species.

Although many jellyfish are harmless to humans and other marine animals, there are also species that can be dangerous. For example, the box jellyfish (Chironex fleckeri) is considered one of the most venomous marine creatures on the planet. This jellyfish has long, thin tentacles that contain short toxic cells called cnidocytes. When an animal or person comes into contact with these tentacles, they stick to the skin and release toxins that can cause extreme pain, irritation, burns, and even death in extreme cases.

Throughout history, jellyfish have fascinated and inspired humans. These creatures have been appreciated for their unique beauty as well as their mysterious and enigmatic appearance. Images of jellyfish have been represented in art, literature, and films, and the study of jellyfish has significantly contributed to the understanding of microorganisms and the evolution of life on Earth.

In conclusion, jellyfish are amazing animals that find their place in marine ecosystems around the world. Their remarkable adaptations and their simultaneously frightening and delicate appearance make them a unique and fascinating presence in the depths of the ocean. Although not all jellyfish species pose a danger to humans, it is important to be aware of their presence and to protect ourselves when venturing into the waters where these creatures inhabit their natural habitat.










Jellyfish are found in all oceans from the surface to the depths. Some jellyfish can be found in fresh water, they are only freshwater species of just 25mm, they are colorless and do not sting.

Jellyfish are generally transparent or translucent. Cyanea capillata is the largest known jellyfish and the longest in the world.

Its tentacles are 36.5 m. the most common giant jellyfish is found in the waters of Japan, Korea and China. Its diameter is about 200cm and weight 200kg. Since jellyfish are not actually fish, the word jellyfish is considered an impromptu term, so American public aquarists have popularized the terms jellies or sea jellies (jellyfishes).

The word jellyfish is used to denote various types of cnidarians, which have the basic body structure resembling an umbrella. Scientists use different terms for jellyfish (for example: gelatinous zooplankton).

Feeding Jellyfish

Even though they are not fish, jellyfish are carnivorous animals. They catch prey with the help of tentacles. Through its tentacles it injects a venom that paralyzes or even kills its prey.

The concentration and composition of the venom differ from one species to another. Certain species of jellyfish develop a venom so powerful that it can kill an adult human in just a few minutes.

Some jellyfish have the ability to swim a little faster by actively chasing their prey if the venom is weaker or the animal has escaped.

Jellyfish consume all types of plankton in life, from plants to microscopic animals in the water. They eat fish roe or larvae from other animals, mollusks, crustaceans, or other species of jellyfish.

Appearance sea jellyfish

Jellyfish have no digestive system, respiratory system, central nervous system or circulatory system. They do not need a respiratory system because their skin is very thin and the body is oxygenated by diffusion.

They have limited control in movement, but they move by contractions-pulsations of the bell body. Some species swim most of the time while others are more passive preferring to save energy.

Jellyfish are composed 90% of water, most of their mass is gelatinous, hence the name Jelly. The jellyfish has no brain and nerve system, but there is a network of nerves located in the epidermis. Some can detect the presence of light with the help of sensitive organs.

Behavior sea jellyfish

The presence of" flowers " in the waters is usually seasonal and occurs with the advent of the sun and the increase in temperature. Ocean currents tend to gather jellyfish in groups of hundreds of thousands of individuals.

Jellyfish are able to survive in oxygen-poor water or salty waters that contain more iodine.

Rising global temperatures mean rising water temperatures mean 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 the waters some jellyfish populations have increased their numbers 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 problems for humans. The most common are stings (sometimes deadly, depending on the species). The other problem is that a lot of people don't know them well but they know that some of them can cause health problems and that affects tourism.

Destroying fishermen's nets is another matter. Only Scyphozoan jellyfish are harvested for consumption, about 12 of the 85 species harvested.

Traditional methods of processing involve procedures that last 20-40 days after the removal of the gonads and mucous membranes.

Umbrella and tentacles are treated with a mixture of salt and several other ingredients. Due to the large amount of water jellyfish loses 7-10% of weight during processing.

After processing the remaining mass contains 94% water and 6% protein. Fresh jellyfish are cream in color, but during prolonged storage the color becomes yellow or brown.

In China jellyfish are processed and left to desarate overnight. The next day they can be eaten boiled or raw. They can be served with oil, soy sauce, vinegar, sugar, as vegetable salad, etc.

In Japan they are cut into slices and served with vinegar as an appetizer.

Breeding sea jellyfish

Jellyfish are usually male or female (occasionally hermaphrodite individuals are also found). In most cases the eggs are released into the water without protection and are fertilized.

In some species sperm swim in the female's mouth to fertilize the eggs inside the body. After fertilization, a larva called a planula is formed.

The Planula is small and covered with cilia. This settles on a rigid surface and develops into a polyp. The polyp is cup-shaped and tentacles begin to appear around an orifice.

Then the jellyfish as we know it develops. The life span of jellyfish lasts from a few hours (in the case of very small hydromeduses) to years, depending on the species.

A species has a longevity of up to 30 years, which is unusual for jellyfish. One species, dohrnii Turritopsis, may be immortal due to the ability to transform between jellyfish and tulip.

They feed continuously. In most species reproduction is controlled by light, so the population spawns at dusk or dawn.

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