It consists of a single nectophore (swimming bell), the exterior of which has five complete longitudinal ridges, the bases of which bend dorsally.

The hydroecium (ventral cavity) is shallow and the somatocyst (part of the gastrovascular system) extends to about half the height of the nectophore.

[2] Muggiaea kochii is found in the neritic zone on both sides of the warm temperate and subtropical Atlantic Ocean.

It is present on the Gulf Coast of the United States where it often occurs in brackish water in bays.

[5] In the Atlantic Ocean, the ranges of M. kochii and M. atlantica only overlap to a limited extent; where one is abundant, the other tends to be uncommon.