It is to be strange to know that jellyfish is not a fish even. This is an animal without skeleton. Jellyfish are members of a large division of very simple animals called "coelenterate" though it is one of the strangest forms of life to be found in the sea. 9/10th of the body of a jellyfish is composed of a jellylike substance and most of it, is simply a stomach cavity. The jellyfish has no blood vessels even a brain.
With its tentacles, the jellyfish often sting people quite painfully. The reason they sting is that their method of obtaining food. The jellyfish capture other small creatures of the sea by stinging them, and this paralyzes their prey. Then the victim is brought to the mouth by the tentacles. Some jellyfish even have stinging organs in the stomach to complete the destruction of the prey. The tentacles are also used for swimming.
With its tentacles, the jellyfish often sting people quite painfully. The reason they sting is that their method of obtaining food. The jellyfish capture other small creatures of the sea by stinging them, and this paralyzes their prey. Then the victim is brought to the mouth by the tentacles. Some jellyfish even have stinging organs in the stomach to complete the destruction of the prey. The tentacles are also used for swimming.