Jellyfish are amazing inhabitants of sea and ocean waters, which are the simplest animals on our planet. They don't have a brain, but they have two nervous systems. In addition, these unusual creatures are able to breathe with their entire body, which is at least 95% water.
To date, scientists have discovered more than 3000 species of jellyfish. They differ not only, for example, in size, but also in life expectancy. Some jellyfish live only 3-5 hours, others for several years. However, there is a special species of these sea creatures called Turritopsis dornii. There is an assumption that these jellyfish are able to live forever.
Jellyfish appear from the testicles. They are originally larvae called planules. At this stage of development, jellyfish are like ciliates of slippers, floating aimlessly in ocean or sea waters. After a while, the planula stick to the bottom or rock, after which they gradually develop polyps that look like translucent or completely transparent corals. Gradually, the polyp transforms into ether, which then becomes a jellyfish. Scientists suggest that the mentioned species Turritopsis dornii is able to go through the stages of development in the opposite order.
Jellyfish can lay more than 30,000 eggs at a time. After the clutch is fertilized by the male.
The amazing creatures got their name in honor of Medusa the Gorgon - a monster from ancient Greek myths. Experts suggest that the inhabitants of the deep water appeared earlier than dinosaurs.
Some jellyfish species have 24 eyes. In this case, in a pair, one eye looks up or straight, the other - down or back. This allows jellyfish to control the entire area around with their gaze. Such vision enables creatures to successfully hunt, hide from enemies and easily navigate the water.
Features of the body structure allow jellyfish to live at a depth of 10 kilometers. As a rule, these animals lead a passive lifestyle. They usually follow the current. However, under certain circumstances, jellyfish are able to swim on their own. To do this, they draw water into their body, which they then sharply "spit out".
Among the species of jellyfish known to science, there are many poisonous. The most dangerous is the sea wasp. Its poison poisons the body of a person or another animal in a matter of seconds. The creature lives near Australia, you can also meet it in Southeast Asia. The length of the tentacles of the sea wasp exceeds 3 meters. Even a light touch on the body of this jellyfish guarantees severe burns on the skin, excruciating pain and long-term discomfort.
An amazing fact: poisonous jellyfish remain deadly to other living creatures even when they are thrown out of the water on the coast. Moreover, some jellyfish, even after their death, are capable of poisoning with poison if you touch them.
These unusual animals live in all the oceans on our planet. The largest jellyfish is the Arctic one. The diameter of its dome is at least 2 meters, and the length of the tentacles reaches 40 meters.
Jellyfish don't often exist alone. As a rule, they gather in groups, the number of which sometimes reaches 2000-3000 individuals. Such congestions of sea creatures are called swarms.
In Asian countries, these creatures are considered a delicacy. In Japan, jellyfish are often bred at home, kept in aquariums. All over the world, since the Middle Ages, jellyfish and their venom have been used in alternative medicine. For example, some animals are used to make drugs that have a laxative effect. And from poisons they make tinctures that relieve diseases affecting the respiratory system, in particular the lungs.
