Salmacina dysteri is a species of tube-forming annelid worm in the family Serpulidae. It is found on submerged rocks, reefs, piles and boats in many shallow and deeper water environments around the world.
Salmacina dysteri lives in a slender white tube that it constructs, which is up to 15 mm (0.6 in) long and 5 mm (0.2 in) wide. It is a gregarious species and forms agglomerations of intertwined tubes. The branchial crown, which projects from the end of the tube, has two groups of four radioles (heavily ciliated, feather-like tentacles). This worm has seven to nine thoracic segments and the tube has no operculum (lid). Unlike the two-layer tubes of many related species, the opaque tube of Salmacina dysteri consists of a single, porous layer. 
Distribution and habitatEdit
It is not clear where this species originated, but it is now found in warm waters globally. It was first seen in Hawaii in 1939, and it occurs there from the eulittoral zone down to around 600 m (2,000 ft). It grows on solid structures such as on rocks, on seaweed on reef flats, on reef slopes and docks, especially in harbours and bays; it also grows on the hulls of ships and on top of other fouling organisms.
Salmacina dysteri is a suspension feeder. Cilia on the tentacles cause currents in the water and small organic particles are caught as they float by. Other cilia move the particles along mucus-filled grooves to the mouth. Experiments have shown that only inert, detrital particles are captured by the expanded crown, free-swimming algae being able to avoid entrapment. 
- WoRMS (2015). "Salmacina dysteri (Huxley, 1855)". WoRMS. World Register of Marine Species. Retrieved 16 March 2016.
- Eldredge, L.G.; Smith, C.M. (2001). "Salmacina dysteri" (PDF). Hawaii Biological Survey 2001. Bishop Museum Technical Reports. Archived from the original (PDF) on 25 September 2012. Retrieved 16 March 2016.
- Eijiroh Nishi (1993). "On the Internal Structure of Calcified Tube Walls in Serpulidae and Spirorbidae (Annelida, Polychaeta)". Marine Fouling. 10: 17–20. doi:10.4282/sosj1979.10.17.
- Phillips Dales, R. (1957). "Some quantitative aspects of feeding in sabellid and serpulid fan worms" (PDF). Journal of the Marine Biological Association of the United Kingdom. 36 (2): 309–316. doi:10.1017/S0025315400016817.