Australian box jellyfish (or australian box jellyfish): Living along the coast of Australia, if people touch its tentacles, they will die after 30 seconds. Box jellyfish, also known as sea wasp, is a coelenterate, which mainly lives in the coastal waters of northeast Australia and often floats in the shallow waters off the coast of Queensland. The box jellyfish is considered to be the most toxic creature known in the world. People can die 30 seconds after being stung. Adult box jellyfish, the size of a football, are mushroom-shaped and almost transparent. On both sides of its body, there are two original eyes, which can feel the change of light, and more than 60 ribbon tentacles are dragged behind it. These tentacles are deadly, and they can extend beyond 3 meters. On each tentacle, capsules are densely arranged, and each capsule has a hollow "poisonous needle" that is invisible to the naked eye and full of venom. An adult box jellyfish has billions of poison sacs and needles on its tentacles, which is enough to kill 20 people, showing its great toxicity and killing ferocity. There are receptors on its tentacles, which can identify protein on the epidermis of fish, shrimp or people. When the box jellyfish found its prey, it quickly drifted over, wrapped its prey firmly with tentacles, and immediately sprayed venom with a poisonous needle. Once the venom is sprayed on people, there will be many bright red scars on the skin immediately, and the venom will soon invade people's hearts, which will kill people in only two to three minutes, and there is no time for rescue.

Why is the box jellyfish so toxic? It is not very clear at present, but researchers have found that its venom mainly damages the heart. A healthy person's heart has millions of muscle cells, all of which are beating with the same rhythm. When the venom of box jellyfish invades the human heart, it will destroy the consistency of the beating rhythm of muscle cells, thus making the heart unable to supply blood normally and leading to rapid death. The study also found that acetic acid can kill the tentacles of box jellyfish, so scientists suggest that tourists who go swimming and diving in Queensland should bring a bottle of vinegar to use when encountering box jellyfish. However, scientists are analyzing the structure of box jellyfish venom, hoping to make a good medicine to prevent and cure it and avoid the death accident caused by box jellyfish again.

Box jellyfish is the most toxic creature known to human beings on the earth, and it also belongs to the first group of animals that first evolved eyes. A new study by Swedish scientists has found that they have developed a set of special eyes similar to human beings, which can help them avoid obstacles deftly in the ocean.

Different from ordinary jellyfish drifting in ocean currents, box jellyfish can swim flexibly in the ocean, make a turn of 180 degrees quickly and shuttle between objects skillfully. The box jellyfish has 24 eyes, which are distributed on the cup-shaped body at the top of the tubular body. These eyes are divided into four different types. The most primitive one can only perceive the intensity of light, but one eye is more delicate and complex, and can perceive the color and the size of objects like the human eye. The distribution of these eyes allows it to see almost 360 degrees in the surrounding environment.

To test the ability of box jellyfish to avoid obstacles, researchers at Lund University in Sweden let them swim in a running pool and put different obstacles in the water. It turns out that they can avoid obstacles of different colors and shapes, but like people in water, they often can't avoid transparent things.