Prostomium with a short median antenna, just reaching the posterior margin of the prostomium and big nuchal slits.
Notopodial postchaetal lobes of the first chaetiger lanceolate to conical, on the following two chaetigers a little longer, from chaetiger 11 the distal end becoming longer and in posterior chaetigers filamentous. Neuropodial postchaetal lobes in the fist chaetiger as long as the notopodial one, posteriorly becoming shorter. Anterior chaetigers with interramal papillae.
From the 17th chaetiger onwards, neuropodia with 4-5 modified chaetae with a thin terminal prolongation.
Gills start on the fourth chaetiger, 7-30 pairs (A. albatrossae-parapodium).
Over 15 mm for over 54 segments.
North Pacific, North Atlantic, northern North Sea, Skagerrak.