Smooth tubeworm

Appearance

Animal quite long, cylindrical, with up to 125 chaetigers, with 7 thoracic chaetigers.
Operculum absent. 24-45 pairs of radioli in 2 spirals, each with 15-25 paired red blotches concealing single lenticular units. Tentacular membrane low (P. tubularia-anterior end). Two thick palps. Collar incised dorsally and laterally; ventral part folded backwards. Peristomium with 2 ocelli.
Thoracic membrane extensive.
Collar chaetae bordered, scarcely geniculate with a slender knee, finely serrated and tapered distally. Thoracic notopodial chaetae winged, finely denticulate. Apomatus-chaetae absent or only in the last thoracic chaetigers. Abdominal neuropodial chaetae sicle-shaped. Abdominal capillaries, very long and thin, with feathery tips. Uncini narrow anteriorly and broadly rounded posteriorly, with many fine teeth on one side. Uncini similar on thorax and abdomen. Uncini from chaetiger 3 onwards (P. tubularia-chaetae). Between the thorax and abdomen are 2 achaetigerous segments.
Pygidium without papillae.

Size:
Up to 50 mm long for 125 chaetigers.

Tube:
Tube 2-8 mm diameter, smooth except for indistinct growth rings. Adhered to the substratum and often irregularly coiled at first, then erect for much of its length. White, but often overgrown.

Colour:
Reddish or orange coloured, thorax greenish with red spotted collar, crown pink with reddish or orange-coloured cross bands.

Distribution

European coasts of Mediterranean Sea and Atlantic Ocean. Possibly found worldwide.

Habitat

On hard substrata on the lower shore and in shallow water.

Reproduction

To reproduce females send pheromones. The male replies and then they synchronize the emission of the sperm and of the eggs, which find each other through the current.

Defense

The body rapidly retracts inside the tube whenever danger is perceived.