Kingdom Animalia Linnaeus, 1758 - animals
   Phylum Sipuncula Rafinesque, 1814 - peanut worms see Class Sipuncula
     Class Sipunculida DeBlainville, 1828 see Subclass Sipunculida
       Order Sipunculiformes E. Cutler & Gibbs, 1985
         Family Sipunculidae Rafinesque, 1814
           Genus Phascolopsis Fisher, 1950
           Genus Siphonomecus Fisher, 1947
           Genus Siphonosoma Spengel, 1912
           Genus Sipunculus Linnaeus, 1767
           Genus Xenosiphon Fisher, 1947