(McCrady, 1857)
Description
Umbrella bell-shaped; mesogloea uniformly thin [Turritopsis nutricula ]. Velum broad. Manubrium large, in transverse section cross-shaped; with vacuolated endoderm cells. Mouth with four simple lips with numerous sessile clusters of nematocysts along whole margin. Four radial canals and ring canal fairly broad; radial canals continued through endodermal masses to stomach.
Gonads in four pairs on interradial walls of stomach. Eggs developing to planulae on manubrium and in subumbrellar cavity.
Eighty to ninety solid marginal tentacles in single row, with adaxial ocelli on their bases.
Size
Umbrella 4-5 mm high and wide.
Colour
Manubrium bright red [T.nutricula-habitus ].
Distribution in the North Sea
North Sea and English Channel.
World distribution
Circum-(sub)tropical.
Remark
The hydroid is known under the name Corydendrium (see Russell, 1953a)
[After Russell, 1953a; Russell, 1955; Kramp, 1959; Kramp, 1961]