M. Sars, 1856
Body long, thin, cylindrical and fragile.
Prostomium broadly rounded, elliptical, longer than broad, no eyes nor antennae. Palps very long, often spiralled. The prostomium is ventrally and laterally enclosed by the U-shaped peristomium.
Anterior part smooth and ciliated dorsally. Anterior part of body with 9 sometimes 10 segments with triangular to oval notopodia. Notopodial chaetae lanceolate. Fourth notopodium with big, distally broadened, obliquely concave hooks. Hooks golden-brown (S. typicus-detail). Neuropodia much reduced. Fifth and sixth chaetiger ventrally with a brown glandular area, seventh and eighth with a white glandular shield.
Mid-body region with 2-10 elongate segments with bi- or trilobed notopodia and bilobed neuropodia. Notopodia with capillaries; neuropodia with triangular uncini. Noto- and neuropodia connected by a lamella in the mid-body.
Posterior body region of many short segments, with cylindrical notopodia and bilobed neuropodia similar to those of the middle region. Notopodial chaetae lanceolate; neuropodial chaetae uncini.
Pygidium small, without appendages.
Up to 130 mm for over 150 segments.
Cylindrical, straight, transparent, with many rings, yellowish to brownish, up to 100 mm long.
In alcohol yellowish to white.
From 2 to 4000 m deep. Tube obliquely in muddy sediments.
Arctic, Northern North Sea to Öresund, North Atlantic to Mediterranean, North Pacific, South Africa.