(Fleming, 1823)
Description
Umbrella bell-shaped, higher than wide, with generally well-developed conical or spherical solid apical projection [Leuckartiara octona ]. Jelly thin, velum narrow. The four radial canals broad and ribbon-like, with smooth or slightly jagged edges; interradial centripetal canals absent.
Gastric peduncle absent, manubrium of varying length (but never extending beyond umbrella margin), with broad base, flask-shaped; attached to radial canals by well-developed mesenteries. Mesenteries along about half the length of the manubrium. Crenulated mouth lips.
Gonads interradial on whole surface of manubrium, horseshoe shaped with horizontal folds directed towards interradii, the diverging folds connected by an interradial, transverse bridge; interradial pits absent.
With 12-24, usually 16, long, hollow, marginal tentacles each with a pronounced abaxial spur, and 16 or more club-shaped marginal rudimentary bulbs, all bulbs with red ocelli.
Young medusae:
L.octona-newly-habitus
L.octona-young
L.octona-young-habitus
Size
Umbrella up to 20 mm or more high.
Colour
[L.octona-habitus ] Manubrium and marginal tentacles a deep flesh-pink to crimson or yellowish brown.
Ecology and depth range
Meropelagic; neritic. In the plankton medusae are chiefly present from April to October, with a peak abundance in more northern waters in late summer.
Distribution in the North Sea
Throughout whole North Sea
World distribution
North Atlantic Ocean, including Mediterranean Sea; Arctic Ocean; E and W South Atlantic and Indo-Pacific Oceans.
[After Russell, 1953a; Russell, 1955; Kramp, 1959; Bouillon, 1999]