''Rhacostoma'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of aequoreid hydrozoans. It is monotypic with a single species, ''Rhacostoma atlanticum''. It has been reported from the Atlantic coastline of North America, Colombia, western and central Africa. The polyp stage is unknown.

Morphology

The medusae reach up to in diameter with the bell height 3–4 times less than the width. Specimens found in the northern waters tend to be transparent, while those found farther south are tinted pink. The broad stomach gives rise to 80–100 non-branching radial canals.

Tentacle In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work main ...

s are slightly more numerous than radial canals and do possess elongated conical bulbs.

References

Aequoreidae Hydrozoan genera Taxa named by Louis Agassiz Monotypic cnidarian genera {{Leptothecata-stub