Suborder Physonectae Haeckel, 1888

Diagnosis

Siphonophora with an apical pneumatophore and beneath it, a series of nectophores (swimming bells), except in the Athorybiidae which lack nectophores or have a reduced nectophore. Two budding zones present in most species, one under the pneumatophore giving nectophores and the other at the basal end of the nectosome, giving the cormidia that form the siphosome. Cormidia of the siphosome with bracts, palpons, gastrozooids and gonophores.

Higher classification

Metazoa, Cnidaria, Medusozoa, Hydrozoa, Leptolinae,  Siphonophorae

References

Kirkpatrick, P. A., & Pugh, P. R. 1984. Siphonophores and velellids. Synopses of the British Fauna (New Series) 29: 1-154.

Pages, F., & Gili, J.-M. 1992. Siphonophores (Cnidaria, Hydrozoa) of the Benguela Current (southeastern Atlantic). Scientia Marina  56: 65-112.

Totton, A. K. 1965. A synopsis of Siphonophora - British Museum (natural History), London: 230 pp.

Classification

Family Agalmatidae

Physonectae with a biserial arrangement of nectophores in the nectosome and a long usually contractile siphosome.

Family Apolemiidae

Physonectae with one or more tentacles between each pair of nectophores. Nectophore deeply hollowed axially, forming a pair of large axial wings. Nectosac very long.

Family Athorybiidae

Physonectae with relatively large pneumatophore. Nectosome greatly reduced or absent. Siphosome reduced to a dense cluster on which the cormidia are arranged in a spiral.

Family Erennidae

Physonectae with uncoiled tentilla bearing a hypertrophied cnidoband. Terminal process devoid of cnidocysts. Nectophores with basic ridge pattern of apico-, infra- and vertical laterals; with apical muscle-free zone on nectosac; radial canals straight or slightly curved. Ostium without mouth plate, opening basally. Pneumatophore without apical pore.

It seems that there exists no suitable picture of a whole animal!

 

Family Forskaliidae

Long-stemmed Physonectae with numerous, multiserially aranged nectophores forming a cone-shaped or cylindrical nectosome.

Family Physophoridae

Physonectae with a laterally expanded lower end of siphosome forming a spiral sac on which the loosely packed, bractless cormidia are borne. Each cormidium has a single, large palpon.

Family Pyrostephidae

Physonectae with long stem (up to 20 pairs of nectophores). Lateral radial canals of nectosac arise separately from the dorsal and ventral canals, and have three lateral loops each. The ventral is straight or has a few minor bends, the dorsal has three or four marked bends; the adaxial side of nectosac lacks musculature and is deeply embayed; tentillum with straight or twisted cnidoband, lacking an involucrum; with terminal filament.

Family Rhodaliidae Haeckel, 1888

Physonectae with nectosome and siphosome contracted to form a globular complex below the enlarged pneumatophore. The gas-secreting area is developed greatly to form a characteristic structure, the aurophore, extending from the baso-dorsal surface of the pneumatophore. The animals are benthic, attaching themselves to the sea-bed by their tentacles.