Hartlaub, 1897
Description
[M.haeckeli-medusa ] Umbrella bell-shaped , slightly higher than wide, without apical process; exumbrella with scattered nematocysts; jelly moderately thick; velum broad. Four radial canals and ring canal narrow. Manubrium short cylindrical, not extending beyond umbrella margin; basal portion of stomach with large transparent endoderm cells. Mouth circular, simple, margin armed with nematocysts. Gonads completely surrounding manubrium, except for basal third; eggs amoeboid, developing into actinulae in bell cavity. Four perradial rounded marginal tentacle bulbs, each with 3-5 solid tentacles, tentacles irregularly distributed, with scattered clusters of nematocysts; ocelli absent.
Size
Umbrella 2 mm high.
Colour
Manubrium dark grey with dark brown pigment granules; marginal bulbs brown.
Ecology and depth range
Medusa and hydroid are planktonic, the hydrant is free-swimming; medusae mainly found during the summer.
Distribution in the North Sea
Common in the North Sea.
World distribution
Unknown.
[After Russell, 1950a; Russell, 1953a; Kramp, 1961]