(O.F. Müller, 1776)
Description
Body oval to spherical; tentacular diameter slightly wider than the sagittal. Rows of ciliary combs equal in length, strating near to the aboral pole and extending more than three quarters of the distance towards the mouth.
Tentacles retractable into sheaths; tentacle base widely separated from the pharyngeal vessel; contractile tentacle may be fifteen to twenty times the length of the body. A row of similar lateral filaments is present along one side of the tentacles.
Colour
Comb rows milky opaque; ectomesoderm glassy transparent; tentacles and sheath and pharynx are milky or in some specimens dull orange in colour.
Juveniles
In newly hatched specimens four pairs of parallel comb rows form clusters of interradially placed long combs; the body is pear shaped and the tentacles develop at the surface. During development the comb rows lengthen and separate, the tentacle base invaginates and the lateral filaments develop, the body becomes more spherical.
Size
Height along the oral-aboral axis in the adult: 10-25 mm.
Depth range
Epipelagic.
Distribution in the North Sea
All North Sea, including Skagerrak and Kattegat; also in Baltic Sea.
World distribution
North Atlantic and the coastal waters of NW Europe.
[After Greve, 1975]