Tentacles 250-350 µm long. So-called statocysts small and difficult to recognize, rounded or kidney-shaped, between nuchal organs and posterior edge of tentacle bases. Eyes absent in adults. Nuchal organs dorsolateral, posterior to statocyst. Transverse band of cilia on ventral side just in front of mouth. Small tufts of cilia scattered on body surface. Prominent ciliary tufts dorsolaterally in angle between posterior edge of tentacle and lateral side of body. Much of body with large number of conspicuous, comparatively long sensory cilia, the longest about 1/2 or 2/3 as wide as body. Several types of epidermal glands: Bacillary glands in the posterior third of the segments. Paired complexes of adhesive glands, each opening on a faint ventrolateral swelling somewhat anterior to middle of each segment. Mature females with elongated, irregular cocoon glands with transparent, oval granules, forming four longitudinal bands along the greater part of the body. Two well-developed adhesive pygidial lobes of somewhat variable shape. Salivary glands extent to segment 5.
Lateral organs in segments 7-13; first pair shaped like rounded depressions, 7th pair lacks glands completely. Two pairs of spermioducts opening into lateral organs of segments 12 and 13. No oviducts in females. Gonads from segment 11 posteriorly.
Up to 3-4 mm for 70 segments.
Transparent, colourless except for a slightly brownish midgut.
Fine to medium sand in shallow subtidal areas; also in intertidal sand beaches down to 60 cm below the surface.
North Sea (Sylt, Helgoland), English Channel, Irish Sea, Skagerrak (Swedish west coast, Gullmarfjord), Atlantic (northern Norway, Tromsö), French Atlantic coast, Mediterranean.