(O.F. Müller, 1766)
Body long and thin with up to 340 segments.
Prostomium conical, slightly longer than broad. Peristomium as long as or slightly longer than the following segments.
Parapodium with a short, rounded prechaetal lobe; postchaetal lobe longer, tongue-shaped, becoming somewhat finger-shaped and extending dorsally in middle and posterior parapodia. Anterior parapodia with winged capillary chaetae. Simple hooded hooks multidentate, starting on chaetigers 15-50. Chaetae dark amber coloured on the basal half; aciculae black (L. fragilis-detail).
Mandibles Y-shaped. Maxillae I: hooked forceps; maxillae II: 4-5 teeth; maxillae III: 1-2 teeth; maxillae IV: unidentate (L. fragilis-jaw plates).
Pygidium with 4 lobes.
Up to 380 mm for 340 segments.
Iridescent, reddish orange, brown or yellowish with whitish transverse bands.
In sand, mud, gravel, broken shells, stones and various combinations of these. Also among Posidonia , from shallow subtidal depths to about 3500 m.
Arctic, North Pacific, North Atlantic up to the Mediterranean, English Channel, whole North Sea, Skagerrak to Öresund.