(Oersted, 1844 in Grube, 1860)
Body small and slender.
Tentacles numerous, unevenly long and thick. Upper lip thick, curving around the mouth and covering it dorsally and laterally. Many eyespots. Gills dichotomous branched with short stems, anterior ones not much longer but more branched than the posterior ones. No lateral lobes. Usually 15 ventral shields. Fifteen chaetigerous thoracic segments, the posterior 14 ones with uncinigerous tori. Uncini in double rows on segments 11-20. Pygidium with smooth or finely scalloped edge. Notopodial chaetae with narrow brims. Uncini with one big and several smaller teeth.
Up to 70 mm for 50 segments.
A thin, soft layer of secretion encrusted with sand grains and detritus.
In life pink or light brown, red stomach visible through the epidermis. In alcohol pale yellow.
On coarse or fine sand, sand mixed with mud, pure mud, or with its tube fixed to Zostera , brown or red algae, or hydroids. Also on hard bottoms; eulittoral to about 500 m; euhaline to mesohaline.
The distribution is uncertain due to confusion with Nicolea venustula .
Northeast Atlantic, North American Atlantic, West Greenland, Canadian Arctic, Novaya Zemlya, Siberian Arctic, Bering Sea, Sea of Okhotsk, Japan Sea, North American Pacific; Iceland, the Faeroes, Jan Mayen, Svalbard, Barents Sea, Tromsø, southern Norway, Kattegat, the 0resund, southern North Sea.