Jellyfish backlit by rays of bright sunlight

Jellyfish

Jellyfish, sometimes known as true jellyfish, are a class of cnidarians found in every ocean of the world from the surface to the seabed. Most are free-swimming, but some are sessile and grow fixed to the seabed. Because jellyfish can't swim against a current, they are classed as planktonic animals - even when they're the size of the huge lion's mane jellyfish, which can grow to over 35m long. Box jellyfish and the Portuguese man o'war are not true jellyfish, although they are related to them.

Scientific name: Scyphozoa

Rank: Class

Common names:

  • Jellies,
  • Scyphozoans,
  • True jellyfish

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