(O.F. Müller, 1788)
Body rather long, tapering posteriorly.
Prostomium rounded quadrangular with 4 eyes, anterior pair larger and with lenses. Prostomium with 2 antennae and 2 annulated palps, thicker and a little longer than the lateral antennae and with 2 rings.
Lateral antennae threadlike and a little longer than the prostomium. Median antenna absent.
6 pairs of annulated tentacular cirri on 3 segments. Parapodia subbiramous. Dorsal and ventral cirri annulated.
Tentacular cirri placed on long cirrophores. Longest tentacular cirri shorter than the dorsal cirri. Dorsal cirri of the same length. Ventral cirri about as long as the parapodial lobes.
Notopodia reduced to an acicula in the cirrophore and a few simple chaetae. Neuropodia conical with additional upper and lower conical lobes and 1 or 2 aciculae. Simple dorsal chaetae capillary, smooth.
Pharynx with 10-12 papillae and 2 jaws.
Body up to 25 mm for 50 segments.
Dorsal yellowish with dark cross-lines, which transform in the posterior body into single spots. Ventrally yellowish to salmon pink, with brown median cross-lines in the posterior body very dark. Cirri lightly coloured.
Arctic, North Atlantic, Mediterranean, English Channel, North Sea, Skagerrak, Kattegat up to Öresund.