Jellyfish are soft, free swimming aquatic animal with gelatinous umbrella shaped bell and trailing tentacles. Bells may beat to gain propulsion and movement. These tentacles can be used to catch prey or to ward off predators by releasing toxins in painful stings. The species of jellyfish are classified in the suborder Rhododendron, which is the main component of cornflower, although not all suborders Rhododendron are considered jellyfish.

Jellyfish can be found in every ocean, from the surface to the deep. Merozoites ("eujellyfish") are only marine organisms, and some similar looking aquatic animals live in fresh water. Large, usually colored jellyfish are common in coastal areas around the world. Jellyfish have roamed the ocean for at least 500 million years, maybe 700 million years or more, making them the oldest multi organ animals.

Most jellyfish do not have specialized digestive system, osmoregulation system, central nervous system, respiratory system or circulatory system. The joystick is a stem like structure hanging from the lower center, usually surrounded by the oral arm and connected to the mouth / anus at the base of the bell. This leads to the stomach cavity, where digestion takes place and nutrients are absorbed. It connects to a radial canal that extends to the edge of the clock, where the antennae are fixed. Most of the nematode sacs that transmit thorns are located on the antennae. Midnight animals also have them around their mouths and stomachs. Jellyfish do not need a respiratory system because their skin is thin enough that their bodies are oxygenated by diffusion. They have limited control over movement, but they can use their hydrostatic skeleton to navigate the contractions of the bell body. Some species swim most of the time, while others are mostly passive. Depending on the species, the body contains between 95% and 98% water. Most of the umbrella material is a gelatinous material (Guo Dong), called middle Guo Dong, surrounded by two protective skin. The top layer is called the epidermis, and the inner layer is called the stomach dermis, lining the intestinal wall.