• Norwegian: sildebeinhydroide


Hydroid stage: The straight, slender stem can reach a height of 10 cm. The closely spaced branches are alternating to left and right. Each animal is sitting on the upper side of the branch, in contrast to the similar Herring-bone hydroid.

Medusa stage: No information.


It is often found on rocky substrate well below the tidal zone, but rarely deeper than 100 meters. It is also recorded on a variety of plants and shells of crustaceans or mollusks.


It is common in the North-East Atlantic Ocean, as far north as Iceland, the Faroe Islands and Norway (Nordland). It has not been found in the Baltic Sea, but otherwise along the European coast, south to the Mediterranean. There are no records from Arctic areas. Records from South-Africa may be caused by ship transport.