Haeckel, 1887
Siphonophores with a relatively large, and for the Portuguese Man O’War enormous, pneumatophore, whose gas gland may bear hypocystic villi. The pneumatophore has an apical pore. No nectosome or bracts are present, and the cormidia are relatively simple comprising only a gastrozooid and tentacle, and a gonodendron. The tentacles, which in some species are unbranched, bear only one type of penetrant nematocyst. The gonodendron bears gonopalpons, gonophores and asexual swimming bells. Each animal probably bears gonophores of only one sex. Only 5 recognised species within two families.
Family Physaliidae
Family Rhizophysidae