Introduction to jellyfish: Jellyfish are important plankton in the aquatic environment and belong to the class Cnidaria jellyfish. Jellyfish is a very beautiful aquatic animal. Its body is shaped like a transparent umbrella. The diameter of the umbrella body can be large or small. The diameter of the large jellyfish's umbrella body can reach 2 meters. There are some whisker-like tentacles on the edge of the umbrella body, and some tentacles can be 20-30 meters long.