Spiral Tubeworm

Sinistral Spiral Tubeworm, Spirorbis borealis

Even though it rarely grows larger than 3mm in diameter, the Sinistral Spiral Tubeworm, Spirorbis borealis is quite conspicuous on the seashore doe to the whiteness of the calcareous tube it forms around itself and the fact that it tends to occur in large numbers (1). Emerging from the tube when submerged, S. borealis filter feeds using feathery appendages in a manner similar to other marine annelids. It is most commonly found on the surfaces of algae such as Fucus and Laminaria species. While it can also be seen on other algae, rocks and mollusc shells, S. borealis larvae when settling tend to favour Fucus and Laminaria surfaces (2). Indeed, this substrate preference is one way of differenciating them from similar species such as S. corallinae and S. tridentatus.

References:

1. Sterry, 2004. Collins Complete Guide to Irish Wildlife p. 174
2. De Silva, 1962. Journal of Experimental Biology 39 pp. 483-490