Trachymedusae

Trachymedusae belong to the phylum Cnidaria and the class Hydrozoa. The Trachymedusae include five families, among which are 30 genera and around 50 species in all. The family Rhopalonematidae has the greatest diversity.

Rhopalonematidae is a family of hydrozoans. The family comprises 15 genera and 36 species.

Halicreatidae is a family of hydrozoans. The family comprises 6 genera and 9 species.

Petasidae is a family of cnidarians belonging to the order Trachymedusae.

Ptychogastriidae is a family of cnidarians belonging to the order Trachymedusae.