(L. Agassiz, 1849)
Description
Umbrella almost globular, sometimes higher than wide [Bougainvillia superciliaris ]; jelly moderately thick; velum well developed. Four broad radial canals and a narrow ring canal [B.superciliaris-medusa ].
Gastric peduncle almost always well developed; manubrium short, with broad base, in section cross-shaped. Mouth with four oral tentacles inserted above mouth opening, dichotomously branched 4-5 times terminating in nematocyst clusters [B.superciliaris-gonads+mouth].
Gonads situated interradially on manubrium walls only; planulae develop in situ within capsules.
Four large marginal tentacular bulbs each with a group of up to 22 (usually 11-15) tentacles of one kind. Ocelli adaxial, on base of each tentacle, ocelli black [B.superciliaris-marginal tentac].
Young medusa: B.superciliaris-young.
Size
Umbrella 6-8 mm high.
Colour
Manubrium brown to reddish brown; marginal bulbs chestnut brown.
Ecology
Season of occurrence in the North Sea is from February to June.
Distribution in the North Sea
Arctic species occurring southwards along the eastern and western North Sea coasts.
World distribution
Eastern N Atlantic Ocean; Arctic Ocean.
[After Russell, 1953a; Russell, 1953b; Kramp, 1959]