Jellyfish Facts



  • Jellyfish are sea creatures with bell-shaped, jelly-like bodies, and long stinging tentacles.
  • Biologists call jellyfish medusa, after the mythical Greek goddess Medusa, who had wriggling snakes for hair.
  • Jellyfish belong to a large group of sea creatures called cnidarians, which also includes corals and anemones.
  • Unlike anemones, jellyfish float about freely, moving by squeezing water out from beneath their body. When a jellyfish stops squeezing, it slowly sinks.
  • A jellyfish’s tentacles are covered with stinging cells called nematocysts, which are used to catch fish and for protection. The stinging cells explode when touched, driving tiny poisonous threads into the victim.
  • Jellyfish vary in size from a few millimetres to over 2 m.
  • The bell of one giant jellyfish measured 2.29 m across. Its tentacles were over 36 m long.
  • The Portuguese man-of-war is not a true jellyfish, but a collection of hundreds of tiny animals called polyps which live together under a gas-filled float.
  • The purple jellyfish can be red, yellow or purple.
  • Jellyfish are among the world’s most ancient animals.