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© PEDRO SZEKELY /FLICKR
Animals have a variety of strategies to ward off predators and capture prey. Some animals use sharp teeth and strong jaws; some rely on camouflage; some secrete highly poisonous...
The jellyfish we are going to talk about today belongs to the last type. Jellyfish are cnidarians with cnidarian sacs that both release toxins and are used for predation, attack and defense.
Cnidaria
First, we need to understand, what are cnidaria?
Cnidaria, taxonomically classified as invertebrates, meaning they do not have a spine on their dorsal side. Except for a few species that live in freshwater, most species live in the ocean, most in shallow seas and some in deep seas. Cnidaria include corals, jellyfish, sea anemones, and polyps, of which there are approximately 11,000 extant species.
The bodies of cnidarians are radially symmetrical, with a body wall composed of two layers of cells, the ectoderm and the endoderm, between which are filled with the gelatinous substances they secrete.
Cnidaria
Cnidocytes are a type of offensive and defensive cell of cnidaria that look like tiny coiled "harpoons". There is a nematocyst in the cnidocyte, which is a very typical feature of cnidarians. There are about 30 different types, depending on the shape of the nematocysts and filaments they emit, which are used for predation, defense, and sometimes even movement.
When undisturbed, the cnidarian barbed wire stays safe in its sac. When physically or chemically disturbed, such as an unsuspecting beach visitor hitting a jellyfish's tentacles, the barbed wire is expelled from the sac.The whole process only takes about 3 milliseconds, and there is no time for people to escape. These stimuli were fired even after the cnidaria died or the tentacles shed.
© PEET J. VANEEDEN
The function of nematocysts varies by species. Some are found on the body surface and outside the tentacles, while others contain toxins that can cause severe pain and possibly death. All jellyfish toxins contain a protein called 'porin', which attacks unfortunate cells. Depending on the amount and proportion of porin, the stinging conditions vary. In mild cases, the skin may become red and swollen, causing pain, and in severe cases, it may even lead to death.
Don't panic if you get stung by a jellyfish.
First, check whether there are stingers left in the stung area. If there are thorns in the skin, they should be pulled out as soon as possible; then you can wet the sting area with vinegar. Note, do not handle with water or alcohol.
Australian box jellyfish
The Australian box jellyfish, alias "sea wasp", is considered one of the most poisonous animals in the ocean. An adult box jellyfish has billions of venom sacs and needles scattered across its tentacles, enough to kill 20 people, showing how venomous it is.
The venom of this jellyfish mainly damages the heart. When their venom invades the human heart, it will destroy the consistency of the beating rhythm of the body cells, so that the heart cannot supply blood normally, resulting in rapid death. The only way to avoid being attacked by box jellyfish is to avoid swimming in waters where these jellyfish are infested.
Fortunately, most cnidaria are not so venomous, but in any case, it is important to keep your distance from these cnidarians.
Australian box jellyfish
The jellyfish has a simple structure and beautiful appearance, but it hides a deadly weapon.
The next time you dive, if you see jellyfish, and you are attracted by their gelatinous bodies and dreamy colors, think about their tentacles covered with "harpoons", if accidentally stung, you may die, you should You won't touch them easily.
Distance is a kind of beauty and a kind of protection.
Sometimes you can only watch from a distance, but it's pretty good~
