Narcomedusae

Narcomedusae is an order of hydrozoans in the subclass Trachylinae. Members of this order do not normally have a polyp stage. The medusa has a dome-shaped bell with thin sides. The tentacles are attached above the lobed margin of the bell with usually a gastric pouch above each. There are no bulbs on the tentacles and no radial canals. Narcomedusans are mostly inhabitants of the open sea and deep waters. They can be found in the Mediterranean in large numbers. Narcomedusae are essential to the ecosystem as they are top-down regulators for the midwater environment.

Solmarisidae is a family of hydrozoans in the order Narcomedusae. The name is sometimes spelled "Solmaridae".

Aeginidae is a family of hydrozoans in the order Narcomedusae. The family comprises 6 genera and 8 species.

Cuninidae is a family of hydrozoans in the order Narcomedusae. They have dome-shaped bells and tentacles set above the undulating margin of the bell. Their gastric pouches contain the gonads situated in line with the tentacles, the number of pouches being the same as the number of tentacles. The pouches do not extend below the points of origin of the primary tentacles. Members of some genera have a peripheral canal system and others do not. No radial canals or secondary tentacles are present.

Csiromedusa medeopolis is a species of hydrozoan described in 2010. It was discovered in the estuarine waters of the River Derwent near to the Commonwealth Scientific and Industrial Research Organisation's Marine and Atmospheric Research branch in Hobart, Tasmania, Australia. C. medeopolis has been described as presenting a new family and genus as well as species.

Tetraplatia is a genus of hydrozoans in the order Narcomedusae. It is the sole genus in the monotypic family Tetraplatidae.