What's is the jellyfish?

In English, jellyfish are called jellyfish. But from just one look you would already know that they are not fish at all. They're not even vertebrates. Jellyfish is a general term for a group of invertebrate animals from the phylum Cnidaria which are umbrella-shaped and have tentacles.

There are so many types of jellyfish. The World Atlas page says that there are more than 2,000 known species of jellyfish. They are divided into classes Scyphozoa (true jellyfish), Staurozoa (stemmed jellyfish), Cubozoa (box jellyfish), and Hydrozoa which are mostly colonizing animals.