Serpula columbiana

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Serpula columbiana, also known as the calcareous tubeworm, plume worm, fan worm, limy tube worm, or red tube worm, is a segmented marine worm in the Serpulidae family. It builds a smooth, irregularly coiled calcareous tube attached to hard surfaces such as rocks, wharves, pilings, or floats. It lives from the intertidal zone down to about 100 meters deep and is found in many Northern Hemisphere seas, including parts of the Atlantic, Pacific, and Indian Oceans, as well as the North Sea and the Mediterranean.

The tube opening is protected by a funnel-shaped operculum with about 160 folds. Inside, the worm is yellowish and up to 8 cm long. It has about 40 radioles (feather-like feeding limbs) that can be extended from the tube opening. The radioles are red, pink, or orange, often with white bands, and are attached to the peristomium, which has a pair of eyes. The worm has seven thoracic segments and up to 190 abdominal segments.

Serpula columbiana is a filter feeder, catching plankton with its radioles. If danger threatens, the radioles can be retracted quickly and the operculum can close to seal the tube. The worm’s heart pumps blood into the radioles, which also act as gills. It has a simple circulatory system with a single branchial vessel in each radiore, with tidal blood flow rather than continuous circulation. The blood pigment is chlorocruorin, which carries oxygen and has a high affinity for carbon monoxide.

Larvae sometimes settle on brown seaweeds like Fucus, but not on Nereocystis. It is thought that Nereocystis’s use of carbon monoxide to inflate its float chambers may make it toxic to the worm.