Jellyfish are not really fish, of course, because a fish's anatomy is centered around its backbone, whereas the jellyfish is a dome-shaped invertebrate. ... The cnidocytes on jellies' tentacles discharge venom from a sac called a nematocyst. These help them to capture floating prey in the water column.

Is a jellyfish a fish or a mammal?

The jellylike creatures pulse along on ocean currents and are abundant in cold and warm ocean water, in deep water, and along coastlines. But despite their name, jellyfish aren't actually fish—they're invertebrates, or animals with no backbones.

What is a jellyfish classified as?

jellyfish, any planktonic marine member of the class Scyphozoa (phylum Cnidaria), a group of invertebrate animals composed of about 200 described species, or of the class Cubozoa (approximately 20 species).