In this way are formed the familiar feathery colonies of Plumularia, in which the pinnules are all in one plane, while in the allied Antennularia the pinnules are arranged in whorls round the main biserial stem.
Club-shaped hydranths with numerous tentacles, generally scattered irregularly, sometimes with a spiral arrangement, or in whorls (" verticillate ").
Hydranth more shortened, daisy-like in form, with two whorls of tentacles, oral and aboral.
Trophosome, polyps with two whorls of tentacles, the lower filiform, the upper capitate; gonosome, free medusae, with tentacles solid and branched.
- Trophosome, polyps with two whorls of tentacles, both filiform.