(Müller, 1774)
Description:
Body is very small.Thorax with 8, abdomen with 3 chaetigers.
Three pairs of radioli with side-branches ending at the same height as the radioli themselves. Collar only ventrally developed, building a triangular lip (F. stellaris-anterior end ). Peristomium with one or two pairs of eyes.
Thoracic notopodia with 4-6 long, winged capillary chaetae. The 2nd and 8th chaetiger have additionally 2-3 short capillaries. Segments 3-7 also with two spatulate chaetae on notopodia.
Thoracic neuropodia with 7-9 hooks with small teeth over the large terminal tooth.
Abdominal neuropodia with 2-3 capillary chaetae. Notopodia with 20-25 uncini with 10-11 rows of small teeth, 3-4 teeth in each row (F. stellaris-chaetae).
Pygidium short and rounded, with a pair of eyes.
Size:
Up to 4.5 mm.
Tube:
Cylindrical, encrusted with mud, detritus or sand; often in colonies.
Colour:
Transparent, yellowish to pink, with brown pigment on the anterior segments.
Habitat:
On sand or mud, usually between algae, ascideans, serpulid tubes or epibiontic. In low water. Tolerates low salinities.
Distribution:
Arctic, North Pacific, North Atlantic to the Mediterranean, English Channel, North Sea to the Baltic, Subantarctic and Antarctic.