This article is about the aquatic animal-form. For similar animals, see gelatinous zooplankton. For other uses, see Jellyfish (disambiguation).

Jellyfish Temporal range: 505–0 Ma PreЄ Є O S D C P T J K Pg N Cambrian – Recent
Pacific sea nettle (Chrysaora fuscescens)
Scientific classification
Kingdom:	Animalia
Phylum:	Cnidaria
Subphylum:	Medusozoa Petersen, 1979
Classes
Cubozoa Hydrozoa Polypodiozoa Scyphozoa Staurozoa

A flower hat jelly (Olindias formosa) photographed at the Osaka Aquarium Kaiyukan

A purple-striped jelly at the Monterey Bay Aquarium

A moon jelly shown in false color at the Pairi Daiza

A white-spotted jellyfish off the north coast of Haiti

Play media

Umbrella Jelly, Shedd Aquarium, Chicago

Jellyfish or jellies^[1] are the major non-polyp form of individuals of the phylum Cnidaria. They are typified as free-swimming marine animals consisting of a gelatinous umbrella-shaped bell and trailing tentacles. The bell can pulsate for locomotion, while stinging tentacles can be used to capture prey.
Jellyfish are found in every ocean, from the surface to the deep sea. Scyphozoans are exclusively marine, but some hydrozoans live in freshwater. Large, often colorful, jellyfish are common in coastal zones worldwide. Jellyfish have roamed the seas for at least 500 million years,^[2] and possibly 700 million years or more, making them the oldest multi-organ animal.^[3]