(Forbes, 1841)
Description
Umbrella usually slightly higher than wide, with quadrangular margin; jelly very thick; velum moderately broad [Bougainvillia britannica ]. Four radial canals broad, ring canal narrow. Gastric peduncle absent, manubrium short, broad based, in section cross-shaped.
Gonads situated adradially on manubrium, sometimes spreading over interradial region of manubrium. Mouth with four oral tentacles inserted above mouth opening, dichotomously branched 4-5 times, basal trunk of oral tentacle long [B.britannica-tentacles].
Four large perradial marginal tentacular bulbs each with a group of 12-17(-30) tentacles of one kind [B.britannica-tentacles]. Ocelli black, elongate transverse.
Development: B.britannica-stages , B.britannica-young-habitus .
Size
Umbrella 6-8 mm high.
Colour
Manubrium yellow; marginal tentacles pale yellow; marginal bulbs bright orange yellow [B.britannica-female-habitus , B.britannica-male-habitus ].
Ecology
In more northern British waters medusae are common in June and July, being recorded as late as September and October.
Distribution in the North Sea
All coasts, as far north as Bergen, Norway.
World distribution
NE Atlantic Ocean including Mediterranean Sea.
[After Russell, 1953a; Russell, 1953b; Kramp, 1959]