(Oersted, 1843)
Description:
Body broad and flattened anteriorly, posterior part of the body arched dorsally and flat ventrally.
Prostomium elongate oval; the posterior part surrounded by the first segment; posterior part with 2-4 small eyes and a long, narrow caruncle reaching segment 1. No tentacles. Two palps at the base of the prostomium, thick and cylindrical, easily lost.
First segment directed anteriorly, with long notopodial postchaetal lobes and long triangular neuropodial postchaetal lobes and anteriorly directed capillary chaetae on notopodia.
Second segment with anteriorly directed spines on neuropodium and notopodium without chaetae. Third notopodium with tri- or quadrilobate postchaetal lobe and capillary chaetae; third neuropodium with broad postchaetal lobe and 4-5 dark, thick spines and thin capillaries. From 3rd segment onwards, parapodia directed horizontally.
Fourth notopodium with serrated postchaetal lobe and capillary chaetae; fourth neuropodium with similar postchaetal lobe and capillary chaetae (T. multisetosa-chaetae 1). Parapodia of segments 5-20 with notopodia with short serrated postchaetal lobes and capillary chaetae and neuropodia with short serrated postchaetal lobes and capillary chaetae and 6-15 spines (T. multisetosa-chaetae 2).
Parapodia of mid-body without notopodia. Neuropodia with a few hairy capillaries and 1-2 spines. Postchaetal lobes simple, finger-shaped.
Posterior region with gradually developing notopodia with 4-7 spines in a star-shaped arrangement (T. multisetosa-parapodium).
From segment 20-40 onwards, 1-4 retractile papillae ventrally on each segment.
Proboscis sack-shaped.
Pygidium weakly lobed or with four obvious lobes in young animals.
Size:
Up to 90 mm for 200 segments.
Tube:
Cylindrical, somewhat flattened, up to 165 mm long and 6 mm broad, made of mud.
Colour:
White or transparent.
Habitat:
Usually in mud, sometimes in fine sand, upper sublittoral to 700 m. In complicated tube-constructions.
Distribution:
Arctic, North Pacific, North Atlantic. Northern North Sea to Baltic Sea.