Feeding and distribution

Glaucus feeding

Glaucus feeding on a Portuguese Man o' War © Bill Rudman


  • The blue glaucus feeds mainly on hydrozoans although they are also known to be cannibalistic.
  • One of the specialities of their diet is the Portugese Man o' War, Physalia physalis (Linnaeus, 1758), best known for the very painful stings they can give if you are unlucky enough to get caught in their tentacles.
  • The glaucus will eat the tentacles, both the fired and unfired stinging cells (nematocysts), and will pass these stings into special pouches in their cerata which they then use for defence.


  • They are found throughout the tropical Atlantic, Pacific and Indians oceans.
  • Glaucus live a pelagic life - this means they go where the winds and currents take them.
  • Keeping air in their stomachs helps them to stay afloat on the surface of the oceans.
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