Jelly fish comes under the phylum

Cnidaria:

1. Cnidarians or coelenterates are multicellular, diploblastic animals with tissue grade of organization and show radial symmetry.
2. These organisms live in freshwater and marine water and can be either non-motile or free-swimming.
3. They got the name due to the presence of specialized cells called cnidoblasts or cnidocytes on their body, for example, Hydra and jellyfish.

Final answer: Jellyfish comes under the phylum Cnidaria