An uncommon species breeding in early summer in sites which are sheltered from wave action but exposed to tidal streams. The normal food is the hydroid Eudendrium arbuscula but other Eudendrium species may be eaten. The spawn consists of a thread which is laid in a wavy spiral coiled amongst the food and on nearby rocks. A northern species in the British Isles, occurring round Scotland and in the Irish Sea, but apparently absent from the western coasts of Ireland and England. There is a single recent record confirmed by a specimen from Lough Hyne, Co Cork.
Further distribution includes Norway and the Atlantic coast of America.
Key Characteristics Long cerata of fairly even size giving a shaggy appearance. White caps covering the tips of the cerata.