Jellyfish Fossil range: 505 mya to present Cambrian – Recent | ||||||
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Pacific sea nettle (Chrysaora fuscescens) at Monterey Bay Aquarium | ||||||
Scientific classification | ||||||
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Included groups | ||||||
Cladistically included but traditionally excluded groups | ||||||
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Jellyfish are animals of the phylum Cnidaria. They are a monophyletic clade, the Medusozoa. Most of them live in the oceans, in salt water, where they eat small sea animals like plankton and little fish, and float in the sea. Only a few jellyfish live in fresh water.