Body long and thin with up to 180 segments.
Prostomium rounded, slightly longer than wide. Peristomium as long as or slightly longer than the following segments.
Parapodia with short prechaetal lobes, which are bluntly oval or subconical; postchaetal lobe longer, tongue-shaped and extending dorsally in middle and posterior segments. Anterior 10-15 parapodia with winged capillary chaetae and with compound multidentate hooded chaetae. Rest of parapodia with winged capillary and/or simple hooded hooks. Chaetae and aciculae yellow (L. gracilis-detail).
Mandibles Y-shaped, transparent. Maxillae I: hooked; maxillae II: 4 teeth each; maxillae III and IV: one tooth each, (L. gracilis-maxillae).
Up to 60 mm for 180 segments.
Iridescent, pale pink or greyish, with minute dark spots.
In mud, sand, stones, coralligene algae and Posidonia from the intertidal zone to depths of 681 m.
Eastern North Atlantic from Norway to the Gulf of Guinea, Mediterranean, Adriatic, Black Sea, English Channel, northern North Sea to Skagerrak.