(M. Sars, 1835)
Description:
Body of this scale-worm tapered posteriorly. Dorsal and ventral surfaces smooth.
Prostomium bilobed. without peaks; with a median antenna, a pair of lateral antennae and a pair of smooth palps. A small conical facial tubercle present between the palps. Two pairs of eyes, the anterior pair just in front of the line of greatest width, the posterior pair in front of the rear margin. A prominent flap covers the posterior part of the prostomium.
First segment without chaetae, bearing an acicular ligule and a pair of dorsal and ventral tentacular cirri.
Scales overlap at the anterior and posterior end of the body, exposing the mid-dorsal area. Scales are rounded, soft and convoluted with smooth margins and surfaces with numerous small conical trifid tubercles.
Notopodia are small mounds with a long ventral acicular ligule and few chaetae. Notopodial chaetae are all long capillaries with fine denticulations. Neuropodia are well developed with a prominent anterior acicular ligule and numerous chaetae. Notopodial chaetae of 2 kinds: 1) upper with blunt tips; 2) slightly swollen on the terminal sixth with rows of spines and bidentate tips (A. gelatinosa-detail).
Size:
Up to 90 mm for 45 chaetigers.
Colour:
Usually pale, buff to grey. Ventral surface yellowish.
Habitat:
Littoral and sublittoral, under stones and among algae, sometimes in the burrows of other polychaetes.
Distribution:
North Atlantic from Faeroes to West Africa, English Channel, North Sea, Skagerrak and Kattegat.