Macrochaeta clavicornis (M. Sars, 1835)

Synonyms:
Nais clavicornis Sars, 1835
Macrochaeta clavicornis McIntosh, 1923

Distinguishing characteristics
One pair of club-shaped palps and 4 pairs of club-shaped branchiae on segments 2-5.
Characteristic compound chaetae with a short lamella on neuropodia.

Species description
Body long and cylindrical and covered with small filiform or conical papillae. Prostomium as long as broad with one pair of large eyes and often an additional pair of very small eyes. One pair of club-shaped palps, not much longer than the prostomium. Four pairs of club-shaped branchiae on segments 2-5, clearly longer than the segment width. One filiform papilla on 3rd segment below the branchiae. Ventral chaetae start at the 4th segment. Dorsal chaetae normally start at the 5th segment. Notopodia with denticulate capillary chaetaea. Neuropodia bear 1-2 compound chaetae with a short lamella on the concave side of the curved tip. Pygidium rounded, with papillae.

Size
Up to 7-10 mm.

Color
Brownish or blackish pigment in between the segments on the anterior body. Phosphorescent.

Habitat
Low water, between seaweeds.

Mobility

Feeding
Deposit feeder.

Life cycle

Distribution
North Atlantic up to Mediterranean, Adriatic Sea, northern North Sea, Skagerrak and Kattegat.