Cnidaria Scyphozoa

• 'true' jellies
• from greek 'skyphos'
• exclusively marine
• two life history phases - medusa and polyp
• four part symmetry
• mesoglea - provides same structural integrity as skeleton, 98% water
• no head, skeleton, specialised organs for respiration/excretion
• lack of a vellum (Dif from hydromedusae) ring of muscle fibres within mesoglea around rim of dome
• swimming in Scyphozoa -> muscles contract against the mesoglea and on relaxation, mesoglea restores shape