Athecate Hydroids (Anthoathecatae) also commonly known as Hydromedusae, is a biological order of the phylum Cnidaria (Cnidarians) and class Hydrozoa (Hydralike Animals).
Acaulidae
Balellidae
Bougainvilliidae
Bythotiaridae
Candelabridae
Cladocorynidae
Cladonematidae
Corymorphidae
Corynidae
Cytaeididae
Eleutheriidae
Eudendriidae
Milleporidae
Halimedusidae
Hydractiniidae
Hydridae
Stylasteridae
Hydrocorynidae
Margelopsidae
Moerisiidae
Monobrachiidae
Oceanidae
Pandeidae
Paragotoeidae
Pennariidae
Polyorchidae
Porpitidae
Proboscidactylidae
Protohydridae
Rathkeidae
Rhysiidae
Russelliidae
Solanderiidae
Sphaerocorynidae
Trichydridae
Tubulariidae
Zancleidae
Zancleopsidae
Actinulida
Anthoathecatae
Limnomedusae
Narcomedusae
Siphonophorae
Leptothecatae
Trachymedusae