[Hydromedusae] See umbrella.

[Cubo-/Scyphomedusae] the dome-shaped body of a medusa, excluding both structures hanging down from it and the marginal tentacles, if present. There is no clear distinction from disc, which is generally applied to the somewhat flatter bells, and the two terms are often interchanged especially when species intermediate in shape are being described. The term umbrella (n.; adj.: umbrellar) covers both. The exumbrella, or exumbrellar surface, is that on the upper side of the bell or umbrella, the subumbrella the underside. The space enclosed by the bell is the subumbrellar cavity, this being filled with sea-water in continuity with the sea itself, in cubomedusae via the velarial aperture.