Amphitritides gracilis

(Grube, 1860)

Description:
Body very long and soft, only slightly tapering, abdomen characteristically rolling up in a corkscrew curl. Tentacles numerous, thin, and moderately long. Eyespots present (not visible on specimens preserved in alcohol). Upper lip low, covering the mouth dorsally and laterally. Two pairs of gills (on segments 2 and 3). Gills dichotomous with distinct stems and short tips, the anterior pair much larger than the posterior one. No lateral lobes. 11-13 ventral shields on thorax.
Notopodial chaetae from segment 4: narrowly winged capillary chaetae, tip sickle-shaped with fine teeth. 17-20 chaetigerous thoracic segments. Uncinigerous tori from segment 5, prominent and long on thorax; inconspicuous and short on abdomen. Uncini in double rows from segment 11 to about 20-30 segments from the pygidium. Uncini with one big and several smaller teeth.
Pygidium with small papillae.

Size:
Up to 120 mm long for up to 200 segments.

Tube:
Unknown.

Colour:
In life body pale red to yellowish grey, tentacles pale, gills red.

Habitat:
On soft mud bottoms and on sand-mixed mud, under stones and among benthic plants and algae. Vertical distribution eulittoral to about 80 m; in euhaline waters only.

Distribution:
Eastern North Atlantic from Scotland to the Ivory Coast, Mediterranean, Black Sea, southern North Sea.

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